diff --git a/ctr-std/Cargo.toml b/ctr-std/Cargo.toml index db79ae3..b7f6da1 100644 --- a/ctr-std/Cargo.toml +++ b/ctr-std/Cargo.toml @@ -14,6 +14,3 @@ path = "../ctru-sys" [dependencies.alloc_system] version = "0.1.1" - -[dependencies.spin] -version = "0.4" diff --git a/ctr-std/src/io/mod.rs b/ctr-std/src/io/mod.rs index 8cb7b2b..58788cd 100644 --- a/ctr-std/src/io/mod.rs +++ b/ctr-std/src/io/mod.rs @@ -256,7 +256,7 @@ #![stable(feature = "rust1", since = "1.0.0")] use cmp; -use std_unicode::str as core_str; +use core::str as core_str; use error as std_error; use fmt; use result; diff --git a/ctr-std/src/lib.rs b/ctr-std/src/lib.rs index 307bb3c..12b2ab4 100644 --- a/ctr-std/src/lib.rs +++ b/ctr-std/src/lib.rs @@ -1,6 +1,7 @@ #![feature(alloc)] #![feature(allow_internal_unstable)] #![feature(box_syntax)] +#![feature(cfg_target_has_atomic)] #![feature(cfg_target_thread_local)] #![feature(collections)] #![feature(collections_bound)] @@ -11,23 +12,30 @@ #![feature(char_escape_debug)] #![feature(dropck_eyepatch)] #![feature(float_extras)] +#![feature(fn_traits)] #![feature(fnbox)] #![feature(fused)] #![feature(generic_param_attrs)] #![feature(int_error_internals)] +#![feature(integer_atomics)] #![feature(lang_items)] #![feature(macro_reexport)] #![feature(oom)] +#![feature(on_unimplemented)] #![feature(optin_builtin_traits)] #![feature(prelude_import)] #![feature(raw)] +#![feature(shared)] #![feature(slice_concat_ext)] #![feature(slice_patterns)] #![feature(staged_api)] #![feature(str_internals)] #![feature(thread_local)] #![feature(try_from)] +#![feature(unboxed_closures)] #![feature(unicode)] +#![feature(unique)] +#![feature(untagged_unions)] #![feature(zero_one)] #![allow(non_camel_case_types, dead_code, unused_features)] #![no_std] @@ -57,9 +65,6 @@ extern crate compiler_builtins; extern crate ctr_libc as libc; extern crate ctru_sys as libctru; -// stealing spin's mutex implementation for now -extern crate spin; - // The standard macros that are not built-in to the compiler. #[macro_use] mod macros; @@ -151,6 +156,7 @@ pub mod ffi; pub mod io; pub mod num; pub mod os; +pub mod panic; pub mod path; pub mod sync; pub mod time; diff --git a/ctr-std/src/panic.rs b/ctr-std/src/panic.rs new file mode 100644 index 0000000..2e037cd --- /dev/null +++ b/ctr-std/src/panic.rs @@ -0,0 +1,394 @@ +// Copyright 2015 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! Panic support in the standard library + +#![stable(feature = "std_panic", since = "1.9.0")] + +use any::Any; +use cell::UnsafeCell; +use fmt; +use ops::{Deref, DerefMut}; +use panicking; +use ptr::{Unique, Shared}; +use rc::Rc; +use sync::{Arc, Mutex, RwLock, atomic}; +use thread::Result; + +//#[stable(feature = "panic_hooks", since = "1.10.0")] +//pub use panicking::{take_hook, set_hook, PanicInfo, Location}; + +/// A marker trait which represents "panic safe" types in Rust. +/// +/// This trait is implemented by default for many types and behaves similarly in +/// terms of inference of implementation to the `Send` and `Sync` traits. The +/// purpose of this trait is to encode what types are safe to cross a `catch_unwind` +/// boundary with no fear of unwind safety. +/// +/// ## What is unwind safety? +/// +/// In Rust a function can "return" early if it either panics or calls a +/// function which transitively panics. This sort of control flow is not always +/// anticipated, and has the possibility of causing subtle bugs through a +/// combination of two cricial components: +/// +/// 1. A data structure is in a temporarily invalid state when the thread +/// panics. +/// 2. This broken invariant is then later observed. +/// +/// Typically in Rust, it is difficult to perform step (2) because catching a +/// panic involves either spawning a thread (which in turns makes it difficult +/// to later witness broken invariants) or using the `catch_unwind` function in this +/// module. Additionally, even if an invariant is witnessed, it typically isn't a +/// problem in Rust because there are no uninitialized values (like in C or C++). +/// +/// It is possible, however, for **logical** invariants to be broken in Rust, +/// which can end up causing behavioral bugs. Another key aspect of unwind safety +/// in Rust is that, in the absence of `unsafe` code, a panic cannot lead to +/// memory unsafety. +/// +/// That was a bit of a whirlwind tour of unwind safety, but for more information +/// about unwind safety and how it applies to Rust, see an [associated RFC][rfc]. +/// +/// [rfc]: https://github.com/rust-lang/rfcs/blob/master/text/1236-stabilize-catch-panic.md +/// +/// ## What is `UnwindSafe`? +/// +/// Now that we've got an idea of what unwind safety is in Rust, it's also +/// important to understand what this trait represents. As mentioned above, one +/// way to witness broken invariants is through the `catch_unwind` function in this +/// module as it allows catching a panic and then re-using the environment of +/// the closure. +/// +/// Simply put, a type `T` implements `UnwindSafe` if it cannot easily allow +/// witnessing a broken invariant through the use of `catch_unwind` (catching a +/// panic). This trait is a marker trait, so it is automatically implemented for +/// many types, and it is also structurally composed (e.g. a struct is unwind +/// safe if all of its components are unwind safe). +/// +/// Note, however, that this is not an unsafe trait, so there is not a succinct +/// contract that this trait is providing. Instead it is intended as more of a +/// "speed bump" to alert users of `catch_unwind` that broken invariants may be +/// witnessed and may need to be accounted for. +/// +/// ## Who implements `UnwindSafe`? +/// +/// Types such as `&mut T` and `&RefCell` are examples which are **not** +/// unwind safe. The general idea is that any mutable state which can be shared +/// across `catch_unwind` is not unwind safe by default. This is because it is very +/// easy to witness a broken invariant outside of `catch_unwind` as the data is +/// simply accessed as usual. +/// +/// Types like `&Mutex`, however, are unwind safe because they implement +/// poisoning by default. They still allow witnessing a broken invariant, but +/// they already provide their own "speed bumps" to do so. +/// +/// ## When should `UnwindSafe` be used? +/// +/// Is not intended that most types or functions need to worry about this trait. +/// It is only used as a bound on the `catch_unwind` function and as mentioned above, +/// the lack of `unsafe` means it is mostly an advisory. The `AssertUnwindSafe` +/// wrapper struct in this module can be used to force this trait to be +/// implemented for any closed over variables passed to the `catch_unwind` function +/// (more on this below). +#[stable(feature = "catch_unwind", since = "1.9.0")] +#[rustc_on_unimplemented = "the type {Self} may not be safely transferred \ + across an unwind boundary"] +pub trait UnwindSafe {} + +/// A marker trait representing types where a shared reference is considered +/// unwind safe. +/// +/// This trait is namely not implemented by `UnsafeCell`, the root of all +/// interior mutability. +/// +/// This is a "helper marker trait" used to provide impl blocks for the +/// `UnwindSafe` trait, for more information see that documentation. +#[stable(feature = "catch_unwind", since = "1.9.0")] +#[rustc_on_unimplemented = "the type {Self} contains interior mutability \ + and a reference may not be safely transferrable \ + across a catch_unwind boundary"] +pub trait RefUnwindSafe {} + +/// A simple wrapper around a type to assert that it is unwind safe. +/// +/// When using `catch_unwind` it may be the case that some of the closed over +/// variables are not unwind safe. For example if `&mut T` is captured the +/// compiler will generate a warning indicating that it is not unwind safe. It +/// may not be the case, however, that this is actually a problem due to the +/// specific usage of `catch_unwind` if unwind safety is specifically taken into +/// account. This wrapper struct is useful for a quick and lightweight +/// annotation that a variable is indeed unwind safe. +/// +/// # Examples +/// +/// One way to use `AssertUnwindSafe` is to assert that the entire closure +/// itself is unwind safe, bypassing all checks for all variables: +/// +/// ``` +/// use std::panic::{self, AssertUnwindSafe}; +/// +/// let mut variable = 4; +/// +/// // This code will not compile because the closure captures `&mut variable` +/// // which is not considered unwind safe by default. +/// +/// // panic::catch_unwind(|| { +/// // variable += 3; +/// // }); +/// +/// // This, however, will compile due to the `AssertUnwindSafe` wrapper +/// let result = panic::catch_unwind(AssertUnwindSafe(|| { +/// variable += 3; +/// })); +/// // ... +/// ``` +/// +/// Wrapping the entire closure amounts to a blanket assertion that all captured +/// variables are unwind safe. This has the downside that if new captures are +/// added in the future, they will also be considered unwind safe. Therefore, +/// you may prefer to just wrap individual captures, as shown below. This is +/// more annotation, but it ensures that if a new capture is added which is not +/// unwind safe, you will get a compilation error at that time, which will +/// allow you to consider whether that new capture in fact represent a bug or +/// not. +/// +/// ``` +/// use std::panic::{self, AssertUnwindSafe}; +/// +/// let mut variable = 4; +/// let other_capture = 3; +/// +/// let result = { +/// let mut wrapper = AssertUnwindSafe(&mut variable); +/// panic::catch_unwind(move || { +/// **wrapper += other_capture; +/// }) +/// }; +/// // ... +/// ``` +#[stable(feature = "catch_unwind", since = "1.9.0")] +pub struct AssertUnwindSafe( + #[stable(feature = "catch_unwind", since = "1.9.0")] + pub T +); + +// Implementations of the `UnwindSafe` trait: +// +// * By default everything is unwind safe +// * pointers T contains mutability of some form are not unwind safe +// * Unique, an owning pointer, lifts an implementation +// * Types like Mutex/RwLock which are explicilty poisoned are unwind safe +// * Our custom AssertUnwindSafe wrapper is indeed unwind safe +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for .. {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl<'a, T: ?Sized> !UnwindSafe for &'a mut T {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl<'a, T: RefUnwindSafe + ?Sized> UnwindSafe for &'a T {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for *const T {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for *mut T {} +#[unstable(feature = "unique", issue = "27730")] +impl UnwindSafe for Unique {} +#[unstable(feature = "shared", issue = "27730")] +impl UnwindSafe for Shared {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for Mutex {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for RwLock {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for AssertUnwindSafe {} + +// not covered via the Shared impl above b/c the inner contents use +// Cell/AtomicUsize, but the usage here is unwind safe so we can lift the +// impl up one level to Arc/Rc itself +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for Rc {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl UnwindSafe for Arc {} + +// Pretty simple implementations for the `RefUnwindSafe` marker trait, +// basically just saying that this is a marker trait and `UnsafeCell` is the +// only thing which doesn't implement it (which then transitively applies to +// everything else). +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl RefUnwindSafe for .. {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl !RefUnwindSafe for UnsafeCell {} +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl RefUnwindSafe for AssertUnwindSafe {} + +#[stable(feature = "unwind_safe_lock_refs", since = "1.12.0")] +impl RefUnwindSafe for Mutex {} +#[stable(feature = "unwind_safe_lock_refs", since = "1.12.0")] +impl RefUnwindSafe for RwLock {} + +#[cfg(target_has_atomic = "ptr")] +#[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")] +impl RefUnwindSafe for atomic::AtomicIsize {} +#[cfg(target_has_atomic = "8")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicI8 {} +#[cfg(target_has_atomic = "16")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicI16 {} +#[cfg(target_has_atomic = "32")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicI32 {} +#[cfg(target_has_atomic = "64")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicI64 {} + +#[cfg(target_has_atomic = "ptr")] +#[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")] +impl RefUnwindSafe for atomic::AtomicUsize {} +#[cfg(target_has_atomic = "8")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicU8 {} +#[cfg(target_has_atomic = "16")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicU16 {} +#[cfg(target_has_atomic = "32")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicU32 {} +#[cfg(target_has_atomic = "64")] +#[unstable(feature = "integer_atomics", issue = "32976")] +impl RefUnwindSafe for atomic::AtomicU64 {} + +#[cfg(target_has_atomic = "8")] +#[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")] +impl RefUnwindSafe for atomic::AtomicBool {} + +#[cfg(target_has_atomic = "ptr")] +#[stable(feature = "unwind_safe_atomic_refs", since = "1.14.0")] +impl RefUnwindSafe for atomic::AtomicPtr {} + +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl Deref for AssertUnwindSafe { + type Target = T; + + fn deref(&self) -> &T { + &self.0 + } +} + +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl DerefMut for AssertUnwindSafe { + fn deref_mut(&mut self) -> &mut T { + &mut self.0 + } +} + +#[stable(feature = "catch_unwind", since = "1.9.0")] +impl R> FnOnce<()> for AssertUnwindSafe { + type Output = R; + + extern "rust-call" fn call_once(self, _args: ()) -> R { + (self.0)() + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for AssertUnwindSafe { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_tuple("AssertUnwindSafe") + .field(&self.0) + .finish() + } +} + +/// Invokes a closure, capturing the cause of an unwinding panic if one occurs. +/// +/// This function will return `Ok` with the closure's result if the closure +/// does not panic, and will return `Err(cause)` if the closure panics. The +/// `cause` returned is the object with which panic was originally invoked. +/// +/// It is currently undefined behavior to unwind from Rust code into foreign +/// code, so this function is particularly useful when Rust is called from +/// another language (normally C). This can run arbitrary Rust code, capturing a +/// panic and allowing a graceful handling of the error. +/// +/// It is **not** recommended to use this function for a general try/catch +/// mechanism. The `Result` type is more appropriate to use for functions that +/// can fail on a regular basis. Additionally, this function is not guaranteed +/// to catch all panics, see the "Notes" section below. +/// +/// The closure provided is required to adhere to the `UnwindSafe` trait to ensure +/// that all captured variables are safe to cross this boundary. The purpose of +/// this bound is to encode the concept of [exception safety][rfc] in the type +/// system. Most usage of this function should not need to worry about this +/// bound as programs are naturally unwind safe without `unsafe` code. If it +/// becomes a problem the associated `AssertUnwindSafe` wrapper type in this +/// module can be used to quickly assert that the usage here is indeed unwind +/// safe. +/// +/// [rfc]: https://github.com/rust-lang/rfcs/blob/master/text/1236-stabilize-catch-panic.md +/// +/// # Notes +/// +/// Note that this function **may not catch all panics** in Rust. A panic in +/// Rust is not always implemented via unwinding, but can be implemented by +/// aborting the process as well. This function *only* catches unwinding panics, +/// not those that abort the process. +/// +/// # Examples +/// +/// ``` +/// use std::panic; +/// +/// let result = panic::catch_unwind(|| { +/// println!("hello!"); +/// }); +/// assert!(result.is_ok()); +/// +/// let result = panic::catch_unwind(|| { +/// panic!("oh no!"); +/// }); +/// assert!(result.is_err()); +/// ``` +#[stable(feature = "catch_unwind", since = "1.9.0")] +pub fn catch_unwind R + UnwindSafe, R>(f: F) -> Result { + unsafe { + panicking::try(f) + } +} + +/// Triggers a panic without invoking the panic hook. +/// +/// This is designed to be used in conjunction with `catch_unwind` to, for +/// example, carry a panic across a layer of C code. +/// +/// # Notes +/// +/// Note that panics in Rust are not always implemented via unwinding, but they +/// may be implemented by aborting the process. If this function is called when +/// panics are implemented this way then this function will abort the process, +/// not trigger an unwind. +/// +/// # Examples +/// +/// ```should_panic +/// use std::panic; +/// +/// let result = panic::catch_unwind(|| { +/// panic!("oh no!"); +/// }); +/// +/// if let Err(err) = result { +/// panic::resume_unwind(err); +/// } +/// ``` +#[stable(feature = "resume_unwind", since = "1.9.0")] +// we always abort so I'm pretty sure there's no reason to ever call this +pub fn resume_unwind(_payload: Box) -> ! { + unimplemented!() +} diff --git a/ctr-std/src/panicking.rs b/ctr-std/src/panicking.rs index e0f9477..efb828a 100644 --- a/ctr-std/src/panicking.rs +++ b/ctr-std/src/panicking.rs @@ -16,6 +16,9 @@ use io::prelude::*; use any::Any; use cell::RefCell; use fmt; +use mem; +use ptr; +use raw; use __core::fmt::Display; thread_local! { @@ -26,11 +29,11 @@ thread_local! { ///The compiler wants this to be here. Otherwise it won't be happy. And we like happy compilers. #[lang = "eh_personality"] -extern fn eh_personality() {} +pub extern fn eh_personality() {} /// Entry point of panic from the libcore crate. #[lang = "panic_fmt"] -extern fn rust_begin_panic(msg: fmt::Arguments, file: &'static str, line: u32) -> ! { +pub extern fn rust_begin_panic(msg: fmt::Arguments, file: &'static str, line: u32) -> ! { begin_panic_fmt(&msg, &(file, line)) } @@ -52,17 +55,127 @@ pub fn begin_panic_fmt(msg: &fmt::Arguments, file_line: &(&'static str, u32)) -> begin_panic(s, file_line); } -/// This is where the main panic logic happens. +/// We don't have stack unwinding, so all we do is print the panic message +/// and then crash or hang the application #[inline(never)] #[cold] pub fn begin_panic(msg: M, file_line: &(&'static str, u32)) -> ! { let msg = Box::new(msg); let (file, line) = *file_line; - print!("--------------------------------------------------"); + use libctru::console::consoleInit; + use libctru::gfx::gfxScreen_t; + + // set up a new console, overwriting whatever was on the top screen + // before we started panicking + let _console = unsafe { consoleInit(gfxScreen_t::GFX_TOP, ptr::null_mut()) }; + println!("PANIC in {} at line {}:", file, line); println!(" {}", msg); - print!("\x1b[29;00H--------------------------------------------------"); + // Terminate the process to ensure that all threads cease when panicking. + unsafe { ::libctru::svc::svcExitProcess() } + + // On 3DS hardware, code execution will have terminated at the above function. + // + // Citra, however, will simply ignore the function and control flow becomes trapped + // in the following loop instead. However, this means that other threads may continue + // to run after a panic! + // + // This is actually a better outcome than calling libc::abort(), which seemingly + // causes the emulator to step into unreachable code, prompting it to freak out + // and spew endless nonsense into the console log. loop {} } + +/// Invoke a closure, capturing the cause of an unwinding panic if one occurs. +pub unsafe fn try R>(f: F) -> Result> { + #[allow(unions_with_drop_fields)] + union Data { + f: F, + r: R, + } + + // We do some sketchy operations with ownership here for the sake of + // performance. We can only pass pointers down to + // `__rust_maybe_catch_panic` (can't pass objects by value), so we do all + // the ownership tracking here manually using a union. + // + // We go through a transition where: + // + // * First, we set the data to be the closure that we're going to call. + // * When we make the function call, the `do_call` function below, we take + // ownership of the function pointer. At this point the `Data` union is + // entirely uninitialized. + // * If the closure successfully returns, we write the return value into the + // data's return slot. Note that `ptr::write` is used as it's overwriting + // uninitialized data. + // * Finally, when we come back out of the `__rust_maybe_catch_panic` we're + // in one of two states: + // + // 1. The closure didn't panic, in which case the return value was + // filled in. We move it out of `data` and return it. + // 2. The closure panicked, in which case the return value wasn't + // filled in. In this case the entire `data` union is invalid, so + // there is no need to drop anything. + // + // Once we stack all that together we should have the "most efficient' + // method of calling a catch panic whilst juggling ownership. + let mut any_data = 0; + let mut any_vtable = 0; + let mut data = Data { + f: f, + }; + + let r = __rust_maybe_catch_panic(do_call::, + &mut data as *mut _ as *mut u8, + &mut any_data, + &mut any_vtable); + + return if r == 0 { + debug_assert!(update_panic_count(0) == 0); + Ok(data.r) + } else { + update_panic_count(-1); + debug_assert!(update_panic_count(0) == 0); + Err(mem::transmute(raw::TraitObject { + data: any_data as *mut _, + vtable: any_vtable as *mut _, + })) + }; + + fn do_call R, R>(data: *mut u8) { + unsafe { + let data = data as *mut Data; + let f = ptr::read(&mut (*data).f); + ptr::write(&mut (*data).r, f()); + } + } +} + +#[cfg(not(test))] +#[doc(hidden)] +#[unstable(feature = "update_panic_count", issue = "0")] +pub fn update_panic_count(amt: isize) -> usize { + use cell::Cell; + thread_local! { static PANIC_COUNT: Cell = Cell::new(0) } + + PANIC_COUNT.with(|c| { + let next = (c.get() as isize + amt) as usize; + c.set(next); + return next + }) +} + +// *Implementation borrowed from the libpanic_abort crate* +// +// Rust's "try" function, but if we're aborting on panics we just call the +// function as there's nothing else we need to do here. +#[allow(improper_ctypes)] +extern fn __rust_maybe_catch_panic(f: fn(*mut u8), + data: *mut u8, + _data_ptr: *mut usize, + _vtable_ptr: *mut usize) -> u32 { + f(data); + 0 +} diff --git a/ctr-std/src/sync/barrier.rs b/ctr-std/src/sync/barrier.rs new file mode 100644 index 0000000..f15e7ff --- /dev/null +++ b/ctr-std/src/sync/barrier.rs @@ -0,0 +1,233 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use fmt; +use sync::{Mutex, Condvar}; + +/// A barrier enables multiple threads to synchronize the beginning +/// of some computation. +/// +/// # Examples +/// +/// ``` +/// use std::sync::{Arc, Barrier}; +/// use std::thread; +/// +/// let mut handles = Vec::with_capacity(10); +/// let barrier = Arc::new(Barrier::new(10)); +/// for _ in 0..10 { +/// let c = barrier.clone(); +/// // The same messages will be printed together. +/// // You will NOT see any interleaving. +/// handles.push(thread::spawn(move|| { +/// println!("before wait"); +/// c.wait(); +/// println!("after wait"); +/// })); +/// } +/// // Wait for other threads to finish. +/// for handle in handles { +/// handle.join().unwrap(); +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Barrier { + lock: Mutex, + cvar: Condvar, + num_threads: usize, +} + +// The inner state of a double barrier +struct BarrierState { + count: usize, + generation_id: usize, +} + +/// A result returned from wait. +/// +/// Currently this opaque structure only has one method, [`.is_leader()`]. Only +/// one thread will receive a result that will return `true` from this function. +/// +/// [`.is_leader()`]: #method.is_leader +/// +/// # Examples +/// +/// ``` +/// use std::sync::Barrier; +/// +/// let barrier = Barrier::new(1); +/// let barrier_wait_result = barrier.wait(); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct BarrierWaitResult(bool); + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for Barrier { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.pad("Barrier { .. }") + } +} + +impl Barrier { + /// Creates a new barrier that can block a given number of threads. + /// + /// A barrier will block `n`-1 threads which call [`wait`] and then wake up + /// all threads at once when the `n`th thread calls [`wait`]. + /// + /// [`wait`]: #method.wait + /// + /// # Examples + /// + /// ``` + /// use std::sync::Barrier; + /// + /// let barrier = Barrier::new(10); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn new(n: usize) -> Barrier { + Barrier { + lock: Mutex::new(BarrierState { + count: 0, + generation_id: 0, + }), + cvar: Condvar::new(), + num_threads: n, + } + } + + /// Blocks the current thread until all threads have rendezvoused here. + /// + /// Barriers are re-usable after all threads have rendezvoused once, and can + /// be used continuously. + /// + /// A single (arbitrary) thread will receive a [`BarrierWaitResult`] that + /// returns `true` from [`is_leader`] when returning from this function, and + /// all other threads will receive a result that will return `false` from + /// [`is_leader`]. + /// + /// [`BarrierWaitResult`]: struct.BarrierWaitResult.html + /// [`is_leader`]: struct.BarrierWaitResult.html#method.is_leader + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, Barrier}; + /// use std::thread; + /// + /// let mut handles = Vec::with_capacity(10); + /// let barrier = Arc::new(Barrier::new(10)); + /// for _ in 0..10 { + /// let c = barrier.clone(); + /// // The same messages will be printed together. + /// // You will NOT see any interleaving. + /// handles.push(thread::spawn(move|| { + /// println!("before wait"); + /// c.wait(); + /// println!("after wait"); + /// })); + /// } + /// // Wait for other threads to finish. + /// for handle in handles { + /// handle.join().unwrap(); + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn wait(&self) -> BarrierWaitResult { + let mut lock = self.lock.lock().unwrap(); + let local_gen = lock.generation_id; + lock.count += 1; + if lock.count < self.num_threads { + // We need a while loop to guard against spurious wakeups. + // http://en.wikipedia.org/wiki/Spurious_wakeup + while local_gen == lock.generation_id && + lock.count < self.num_threads { + lock = self.cvar.wait(lock).unwrap(); + } + BarrierWaitResult(false) + } else { + lock.count = 0; + lock.generation_id += 1; + self.cvar.notify_all(); + BarrierWaitResult(true) + } + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for BarrierWaitResult { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_struct("BarrierWaitResult") + .field("is_leader", &self.is_leader()) + .finish() + } +} + +impl BarrierWaitResult { + /// Returns whether this thread from [`wait`] is the "leader thread". + /// + /// Only one thread will have `true` returned from their result, all other + /// threads will have `false` returned. + /// + /// [`wait`]: struct.Barrier.html#method.wait + /// + /// # Examples + /// + /// ``` + /// use std::sync::Barrier; + /// + /// let barrier = Barrier::new(1); + /// let barrier_wait_result = barrier.wait(); + /// println!("{:?}", barrier_wait_result.is_leader()); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn is_leader(&self) -> bool { self.0 } +} + +#[cfg(test)] +mod tests { + use sync::{Arc, Barrier}; + use sync::mpsc::{channel, TryRecvError}; + use thread; + + #[test] + #[cfg_attr(target_os = "emscripten", ignore)] + fn test_barrier() { + const N: usize = 10; + + let barrier = Arc::new(Barrier::new(N)); + let (tx, rx) = channel(); + + for _ in 0..N - 1 { + let c = barrier.clone(); + let tx = tx.clone(); + thread::spawn(move|| { + tx.send(c.wait().is_leader()).unwrap(); + }); + } + + // At this point, all spawned threads should be blocked, + // so we shouldn't get anything from the port + assert!(match rx.try_recv() { + Err(TryRecvError::Empty) => true, + _ => false, + }); + + let mut leader_found = barrier.wait().is_leader(); + + // Now, the barrier is cleared and we should get data. + for _ in 0..N - 1 { + if rx.recv().unwrap() { + assert!(!leader_found); + leader_found = true; + } + } + assert!(leader_found); + } +} diff --git a/ctr-std/src/sync/condvar.rs b/ctr-std/src/sync/condvar.rs new file mode 100644 index 0000000..68c7e88 --- /dev/null +++ b/ctr-std/src/sync/condvar.rs @@ -0,0 +1,589 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use fmt; +use sync::atomic::{AtomicUsize, Ordering}; +use sync::{mutex, MutexGuard, PoisonError}; +use sys_common::condvar as sys; +use sys_common::mutex as sys_mutex; +use sys_common::poison::{self, LockResult}; +use time::Duration; + +/// A type indicating whether a timed wait on a condition variable returned +/// due to a time out or not. +/// +/// It is returned by the [`wait_timeout`] method. +/// +/// [`wait_timeout`]: struct.Condvar.html#method.wait_timeout +#[derive(Debug, PartialEq, Eq, Copy, Clone)] +#[stable(feature = "wait_timeout", since = "1.5.0")] +pub struct WaitTimeoutResult(bool); + +impl WaitTimeoutResult { + /// Returns whether the wait was known to have timed out. + /// + /// # Examples + /// + /// This example spawns a thread which will update the boolean value and + /// then wait 100 milliseconds before notifying the condvar. + /// + /// The main thread will wait with a timeout on the condvar and then leave + /// once the boolean has been updated and notified. + /// + /// ``` + /// use std::sync::{Arc, Mutex, Condvar}; + /// use std::thread; + /// use std::time::Duration; + /// + /// let pair = Arc::new((Mutex::new(false), Condvar::new())); + /// let pair2 = pair.clone(); + /// + /// thread::spawn(move|| { + /// let &(ref lock, ref cvar) = &*pair2; + /// let mut started = lock.lock().unwrap(); + /// // We update the boolean value. + /// *started = true; + /// // Let's wait 20 milliseconds before notifying the condvar. + /// thread::sleep(Duration::from_millis(20)); + /// cvar.notify_one(); + /// }); + /// + /// // Wait for the thread to start up. + /// let &(ref lock, ref cvar) = &*pair; + /// let mut started = lock.lock().unwrap(); + /// loop { + /// // Let's put a timeout on the condvar's wait. + /// let result = cvar.wait_timeout(started, Duration::from_millis(10)).unwrap(); + /// // 10 milliseconds have passed, or maybe the value changed! + /// started = result.0; + /// if *started == true { + /// // We received the notification and the value has been updated, we can leave. + /// break + /// } + /// } + /// ``` + #[stable(feature = "wait_timeout", since = "1.5.0")] + pub fn timed_out(&self) -> bool { + self.0 + } +} + +/// A Condition Variable +/// +/// Condition variables represent the ability to block a thread such that it +/// consumes no CPU time while waiting for an event to occur. Condition +/// variables are typically associated with a boolean predicate (a condition) +/// and a mutex. The predicate is always verified inside of the mutex before +/// determining that a thread must block. +/// +/// Functions in this module will block the current **thread** of execution and +/// are bindings to system-provided condition variables where possible. Note +/// that this module places one additional restriction over the system condition +/// variables: each condvar can be used with precisely one mutex at runtime. Any +/// attempt to use multiple mutexes on the same condition variable will result +/// in a runtime panic. If this is not desired, then the unsafe primitives in +/// `sys` do not have this restriction but may result in undefined behavior. +/// +/// # Examples +/// +/// ``` +/// use std::sync::{Arc, Mutex, Condvar}; +/// use std::thread; +/// +/// let pair = Arc::new((Mutex::new(false), Condvar::new())); +/// let pair2 = pair.clone(); +/// +/// // Inside of our lock, spawn a new thread, and then wait for it to start. +/// thread::spawn(move|| { +/// let &(ref lock, ref cvar) = &*pair2; +/// let mut started = lock.lock().unwrap(); +/// *started = true; +/// // We notify the condvar that the value has changed. +/// cvar.notify_one(); +/// }); +/// +/// // Wait for the thread to start up. +/// let &(ref lock, ref cvar) = &*pair; +/// let mut started = lock.lock().unwrap(); +/// while !*started { +/// started = cvar.wait(started).unwrap(); +/// } +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Condvar { + inner: Box, + mutex: AtomicUsize, +} + +impl Condvar { + /// Creates a new condition variable which is ready to be waited on and + /// notified. + /// + /// # Examples + /// + /// ``` + /// use std::sync::Condvar; + /// + /// let condvar = Condvar::new(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn new() -> Condvar { + let mut c = Condvar { + inner: box sys::Condvar::new(), + mutex: AtomicUsize::new(0), + }; + unsafe { + c.inner.init(); + } + c + } + + /// Blocks the current thread until this condition variable receives a + /// notification. + /// + /// This function will atomically unlock the mutex specified (represented by + /// `guard`) and block the current thread. This means that any calls + /// to [`notify_one()`] or [`notify_all()`] which happen logically after the + /// mutex is unlocked are candidates to wake this thread up. When this + /// function call returns, the lock specified will have been re-acquired. + /// + /// Note that this function is susceptible to spurious wakeups. Condition + /// variables normally have a boolean predicate associated with them, and + /// the predicate must always be checked each time this function returns to + /// protect against spurious wakeups. + /// + /// # Errors + /// + /// This function will return an error if the mutex being waited on is + /// poisoned when this thread re-acquires the lock. For more information, + /// see information about [poisoning] on the [`Mutex`] type. + /// + /// # Panics + /// + /// This function will [`panic!()`] if it is used with more than one mutex + /// over time. Each condition variable is dynamically bound to exactly one + /// mutex to ensure defined behavior across platforms. If this functionality + /// is not desired, then unsafe primitives in `sys` are provided. + /// + /// [`notify_one()`]: #method.notify_one + /// [`notify_all()`]: #method.notify_all + /// [poisoning]: ../sync/struct.Mutex.html#poisoning + /// [`Mutex`]: ../sync/struct.Mutex.html + /// [`panic!()`]: ../../std/macro.panic.html + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, Mutex, Condvar}; + /// use std::thread; + /// + /// let pair = Arc::new((Mutex::new(false), Condvar::new())); + /// let pair2 = pair.clone(); + /// + /// thread::spawn(move|| { + /// let &(ref lock, ref cvar) = &*pair2; + /// let mut started = lock.lock().unwrap(); + /// *started = true; + /// // We notify the condvar that the value has changed. + /// cvar.notify_one(); + /// }); + /// + /// // Wait for the thread to start up. + /// let &(ref lock, ref cvar) = &*pair; + /// let mut started = lock.lock().unwrap(); + /// // As long as the value inside the `Mutex` is false, we wait. + /// while !*started { + /// started = cvar.wait(started).unwrap(); + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn wait<'a, T>(&self, guard: MutexGuard<'a, T>) + -> LockResult> { + let poisoned = unsafe { + let lock = mutex::guard_lock(&guard); + self.verify(lock); + self.inner.wait(lock); + mutex::guard_poison(&guard).get() + }; + if poisoned { + Err(PoisonError::new(guard)) + } else { + Ok(guard) + } + } + + /// Waits on this condition variable for a notification, timing out after a + /// specified duration. + /// + /// The semantics of this function are equivalent to [`wait`] + /// except that the thread will be blocked for roughly no longer + /// than `ms` milliseconds. This method should not be used for + /// precise timing due to anomalies such as preemption or platform + /// differences that may not cause the maximum amount of time + /// waited to be precisely `ms`. + /// + /// Note that the best effort is made to ensure that the time waited is + /// measured with a monotonic clock, and not affected by the changes made to + /// the system time. + /// + /// The returned boolean is `false` only if the timeout is known + /// to have elapsed. + /// + /// Like [`wait`], the lock specified will be re-acquired when this function + /// returns, regardless of whether the timeout elapsed or not. + /// + /// [`wait`]: #method.wait + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, Mutex, Condvar}; + /// use std::thread; + /// + /// let pair = Arc::new((Mutex::new(false), Condvar::new())); + /// let pair2 = pair.clone(); + /// + /// thread::spawn(move|| { + /// let &(ref lock, ref cvar) = &*pair2; + /// let mut started = lock.lock().unwrap(); + /// *started = true; + /// // We notify the condvar that the value has changed. + /// cvar.notify_one(); + /// }); + /// + /// // Wait for the thread to start up. + /// let &(ref lock, ref cvar) = &*pair; + /// let mut started = lock.lock().unwrap(); + /// // As long as the value inside the `Mutex` is false, we wait. + /// loop { + /// let result = cvar.wait_timeout_ms(started, 10).unwrap(); + /// // 10 milliseconds have passed, or maybe the value changed! + /// started = result.0; + /// if *started == true { + /// // We received the notification and the value has been updated, we can leave. + /// break + /// } + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + #[rustc_deprecated(since = "1.6.0", reason = "replaced by `std::sync::Condvar::wait_timeout`")] + pub fn wait_timeout_ms<'a, T>(&self, guard: MutexGuard<'a, T>, ms: u32) + -> LockResult<(MutexGuard<'a, T>, bool)> { + let res = self.wait_timeout(guard, Duration::from_millis(ms as u64)); + poison::map_result(res, |(a, b)| { + (a, !b.timed_out()) + }) + } + + /// Waits on this condition variable for a notification, timing out after a + /// specified duration. + /// + /// The semantics of this function are equivalent to [`wait`] except that + /// the thread will be blocked for roughly no longer than `dur`. This + /// method should not be used for precise timing due to anomalies such as + /// preemption or platform differences that may not cause the maximum + /// amount of time waited to be precisely `dur`. + /// + /// Note that the best effort is made to ensure that the time waited is + /// measured with a monotonic clock, and not affected by the changes made to + /// the system time. + /// + /// The returned [`WaitTimeoutResult`] value indicates if the timeout is + /// known to have elapsed. + /// + /// Like [`wait`], the lock specified will be re-acquired when this function + /// returns, regardless of whether the timeout elapsed or not. + /// + /// [`wait`]: #method.wait + /// [`WaitTimeoutResult`]: struct.WaitTimeoutResult.html + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, Mutex, Condvar}; + /// use std::thread; + /// use std::time::Duration; + /// + /// let pair = Arc::new((Mutex::new(false), Condvar::new())); + /// let pair2 = pair.clone(); + /// + /// thread::spawn(move|| { + /// let &(ref lock, ref cvar) = &*pair2; + /// let mut started = lock.lock().unwrap(); + /// *started = true; + /// // We notify the condvar that the value has changed. + /// cvar.notify_one(); + /// }); + /// + /// // wait for the thread to start up + /// let &(ref lock, ref cvar) = &*pair; + /// let mut started = lock.lock().unwrap(); + /// // as long as the value inside the `Mutex` is false, we wait + /// loop { + /// let result = cvar.wait_timeout(started, Duration::from_millis(10)).unwrap(); + /// // 10 milliseconds have passed, or maybe the value changed! + /// started = result.0; + /// if *started == true { + /// // We received the notification and the value has been updated, we can leave. + /// break + /// } + /// } + /// ``` + #[stable(feature = "wait_timeout", since = "1.5.0")] + pub fn wait_timeout<'a, T>(&self, guard: MutexGuard<'a, T>, + dur: Duration) + -> LockResult<(MutexGuard<'a, T>, WaitTimeoutResult)> { + let (poisoned, result) = unsafe { + let lock = mutex::guard_lock(&guard); + self.verify(lock); + let success = self.inner.wait_timeout(lock, dur); + (mutex::guard_poison(&guard).get(), WaitTimeoutResult(!success)) + }; + if poisoned { + Err(PoisonError::new((guard, result))) + } else { + Ok((guard, result)) + } + } + + /// Wakes up one blocked thread on this condvar. + /// + /// If there is a blocked thread on this condition variable, then it will + /// be woken up from its call to [`wait`] or [`wait_timeout`]. Calls to + /// `notify_one` are not buffered in any way. + /// + /// To wake up all threads, see [`notify_all()`]. + /// + /// [`wait`]: #method.wait + /// [`wait_timeout`]: #method.wait_timeout + /// [`notify_all()`]: #method.notify_all + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, Mutex, Condvar}; + /// use std::thread; + /// + /// let pair = Arc::new((Mutex::new(false), Condvar::new())); + /// let pair2 = pair.clone(); + /// + /// thread::spawn(move|| { + /// let &(ref lock, ref cvar) = &*pair2; + /// let mut started = lock.lock().unwrap(); + /// *started = true; + /// // We notify the condvar that the value has changed. + /// cvar.notify_one(); + /// }); + /// + /// // Wait for the thread to start up. + /// let &(ref lock, ref cvar) = &*pair; + /// let mut started = lock.lock().unwrap(); + /// // As long as the value inside the `Mutex` is false, we wait. + /// while !*started { + /// started = cvar.wait(started).unwrap(); + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn notify_one(&self) { + unsafe { self.inner.notify_one() } + } + + /// Wakes up all blocked threads on this condvar. + /// + /// This method will ensure that any current waiters on the condition + /// variable are awoken. Calls to `notify_all()` are not buffered in any + /// way. + /// + /// To wake up only one thread, see [`notify_one()`]. + /// + /// [`notify_one()`]: #method.notify_one + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Arc, Mutex, Condvar}; + /// use std::thread; + /// + /// let pair = Arc::new((Mutex::new(false), Condvar::new())); + /// let pair2 = pair.clone(); + /// + /// thread::spawn(move|| { + /// let &(ref lock, ref cvar) = &*pair2; + /// let mut started = lock.lock().unwrap(); + /// *started = true; + /// // We notify the condvar that the value has changed. + /// cvar.notify_all(); + /// }); + /// + /// // Wait for the thread to start up. + /// let &(ref lock, ref cvar) = &*pair; + /// let mut started = lock.lock().unwrap(); + /// // As long as the value inside the `Mutex` is false, we wait. + /// while !*started { + /// started = cvar.wait(started).unwrap(); + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn notify_all(&self) { + unsafe { self.inner.notify_all() } + } + + fn verify(&self, mutex: &sys_mutex::Mutex) { + let addr = mutex as *const _ as usize; + match self.mutex.compare_and_swap(0, addr, Ordering::SeqCst) { + // If we got out 0, then we have successfully bound the mutex to + // this cvar. + 0 => {} + + // If we get out a value that's the same as `addr`, then someone + // already beat us to the punch. + n if n == addr => {} + + // Anything else and we're using more than one mutex on this cvar, + // which is currently disallowed. + _ => panic!("attempted to use a condition variable with two \ + mutexes"), + } + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for Condvar { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.pad("Condvar { .. }") + } +} + +#[stable(feature = "condvar_default", since = "1.9.0")] +impl Default for Condvar { + /// Creates a `Condvar` which is ready to be waited on and notified. + fn default() -> Condvar { + Condvar::new() + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Drop for Condvar { + fn drop(&mut self) { + unsafe { self.inner.destroy() } + } +} + +#[cfg(test)] +mod tests { + use sync::mpsc::channel; + use sync::{Condvar, Mutex, Arc}; + use thread; + use time::Duration; + use u32; + + #[test] + fn smoke() { + let c = Condvar::new(); + c.notify_one(); + c.notify_all(); + } + + #[test] + #[cfg_attr(target_os = "emscripten", ignore)] + fn notify_one() { + let m = Arc::new(Mutex::new(())); + let m2 = m.clone(); + let c = Arc::new(Condvar::new()); + let c2 = c.clone(); + + let g = m.lock().unwrap(); + let _t = thread::spawn(move|| { + let _g = m2.lock().unwrap(); + c2.notify_one(); + }); + let g = c.wait(g).unwrap(); + drop(g); + } + + #[test] + #[cfg_attr(target_os = "emscripten", ignore)] + fn notify_all() { + const N: usize = 10; + + let data = Arc::new((Mutex::new(0), Condvar::new())); + let (tx, rx) = channel(); + for _ in 0..N { + let data = data.clone(); + let tx = tx.clone(); + thread::spawn(move|| { + let &(ref lock, ref cond) = &*data; + let mut cnt = lock.lock().unwrap(); + *cnt += 1; + if *cnt == N { + tx.send(()).unwrap(); + } + while *cnt != 0 { + cnt = cond.wait(cnt).unwrap(); + } + tx.send(()).unwrap(); + }); + } + drop(tx); + + let &(ref lock, ref cond) = &*data; + rx.recv().unwrap(); + let mut cnt = lock.lock().unwrap(); + *cnt = 0; + cond.notify_all(); + drop(cnt); + + for _ in 0..N { + rx.recv().unwrap(); + } + } + + #[test] + #[cfg_attr(target_os = "emscripten", ignore)] + fn wait_timeout_ms() { + let m = Arc::new(Mutex::new(())); + let m2 = m.clone(); + let c = Arc::new(Condvar::new()); + let c2 = c.clone(); + + let g = m.lock().unwrap(); + let (g, _no_timeout) = c.wait_timeout(g, Duration::from_millis(1)).unwrap(); + // spurious wakeups mean this isn't necessarily true + // assert!(!no_timeout); + let _t = thread::spawn(move || { + let _g = m2.lock().unwrap(); + c2.notify_one(); + }); + let (g, timeout_res) = c.wait_timeout(g, Duration::from_millis(u32::MAX as u64)).unwrap(); + assert!(!timeout_res.timed_out()); + drop(g); + } + + #[test] + #[should_panic] + #[cfg_attr(target_os = "emscripten", ignore)] + fn two_mutexes() { + let m = Arc::new(Mutex::new(())); + let m2 = m.clone(); + let c = Arc::new(Condvar::new()); + let c2 = c.clone(); + + let mut g = m.lock().unwrap(); + let _t = thread::spawn(move|| { + let _g = m2.lock().unwrap(); + c2.notify_one(); + }); + g = c.wait(g).unwrap(); + drop(g); + + let m = Mutex::new(()); + let _ = c.wait(m.lock().unwrap()).unwrap(); + } +} diff --git a/ctr-std/src/sync/mod.rs b/ctr-std/src/sync/mod.rs index df954cd..289b47b 100644 --- a/ctr-std/src/sync/mod.rs +++ b/ctr-std/src/sync/mod.rs @@ -21,9 +21,24 @@ pub use alloc::arc::{Arc, Weak}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::sync::atomic; + +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::barrier::{Barrier, BarrierWaitResult}; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::condvar::{Condvar, WaitTimeoutResult}; #[stable(feature = "rust1", since = "1.0.0")] pub use self::mutex::{Mutex, MutexGuard}; #[stable(feature = "rust1", since = "1.0.0")] +pub use self::once::{Once, OnceState, ONCE_INIT}; +#[stable(feature = "rust1", since = "1.0.0")] pub use sys_common::poison::{PoisonError, TryLockError, TryLockResult, LockResult}; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::rwlock::{RwLock, RwLockReadGuard, RwLockWriteGuard}; + +pub mod mpsc; +mod barrier; +mod condvar; mod mutex; +mod once; +mod rwlock; diff --git a/ctr-std/src/sync/mpsc/blocking.rs b/ctr-std/src/sync/mpsc/blocking.rs new file mode 100644 index 0000000..0f9ef6f --- /dev/null +++ b/ctr-std/src/sync/mpsc/blocking.rs @@ -0,0 +1,96 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! Generic support for building blocking abstractions. + +use thread::{self, Thread}; +use sync::atomic::{AtomicBool, Ordering}; +use sync::Arc; +use mem; +use time::Instant; + +struct Inner { + thread: Thread, + woken: AtomicBool, +} + +unsafe impl Send for Inner {} +unsafe impl Sync for Inner {} + +#[derive(Clone)] +pub struct SignalToken { + inner: Arc, +} + +pub struct WaitToken { + inner: Arc, +} + +impl !Send for WaitToken {} + +impl !Sync for WaitToken {} + +pub fn tokens() -> (WaitToken, SignalToken) { + let inner = Arc::new(Inner { + thread: thread::current(), + woken: AtomicBool::new(false), + }); + let wait_token = WaitToken { + inner: inner.clone(), + }; + let signal_token = SignalToken { + inner: inner + }; + (wait_token, signal_token) +} + +impl SignalToken { + pub fn signal(&self) -> bool { + let wake = !self.inner.woken.compare_and_swap(false, true, Ordering::SeqCst); + if wake { + self.inner.thread.unpark(); + } + wake + } + + /// Convert to an unsafe usize value. Useful for storing in a pipe's state + /// flag. + #[inline] + pub unsafe fn cast_to_usize(self) -> usize { + mem::transmute(self.inner) + } + + /// Convert from an unsafe usize value. Useful for retrieving a pipe's state + /// flag. + #[inline] + pub unsafe fn cast_from_usize(signal_ptr: usize) -> SignalToken { + SignalToken { inner: mem::transmute(signal_ptr) } + } +} + +impl WaitToken { + pub fn wait(self) { + while !self.inner.woken.load(Ordering::SeqCst) { + thread::park() + } + } + + /// Returns true if we wake up normally, false otherwise. + pub fn wait_max_until(self, end: Instant) -> bool { + while !self.inner.woken.load(Ordering::SeqCst) { + let now = Instant::now(); + if now >= end { + return false; + } + thread::park_timeout(end - now) + } + true + } +} diff --git a/ctr-std/src/sync/mpsc/mod.rs b/ctr-std/src/sync/mpsc/mod.rs new file mode 100644 index 0000000..aeeab17 --- /dev/null +++ b/ctr-std/src/sync/mpsc/mod.rs @@ -0,0 +1,2614 @@ +// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! Multi-producer, single-consumer FIFO queue communication primitives. +//! +//! This module provides message-based communication over channels, concretely +//! defined among three types: +//! +//! * `Sender` +//! * `SyncSender` +//! * `Receiver` +//! +//! A `Sender` or `SyncSender` is used to send data to a `Receiver`. Both +//! senders are clone-able (multi-producer) such that many threads can send +//! simultaneously to one receiver (single-consumer). +//! +//! These channels come in two flavors: +//! +//! 1. An asynchronous, infinitely buffered channel. The `channel()` function +//! will return a `(Sender, Receiver)` tuple where all sends will be +//! **asynchronous** (they never block). The channel conceptually has an +//! infinite buffer. +//! +//! 2. A synchronous, bounded channel. The `sync_channel()` function will return +//! a `(SyncSender, Receiver)` tuple where the storage for pending messages +//! is a pre-allocated buffer of a fixed size. All sends will be +//! **synchronous** by blocking until there is buffer space available. Note +//! that a bound of 0 is allowed, causing the channel to become a +//! "rendezvous" channel where each sender atomically hands off a message to +//! a receiver. +//! +//! ## Disconnection +//! +//! The send and receive operations on channels will all return a `Result` +//! indicating whether the operation succeeded or not. An unsuccessful operation +//! is normally indicative of the other half of a channel having "hung up" by +//! being dropped in its corresponding thread. +//! +//! Once half of a channel has been deallocated, most operations can no longer +//! continue to make progress, so `Err` will be returned. Many applications will +//! continue to `unwrap()` the results returned from this module, instigating a +//! propagation of failure among threads if one unexpectedly dies. +//! +//! # Examples +//! +//! Simple usage: +//! +//! ``` +//! use std::thread; +//! use std::sync::mpsc::channel; +//! +//! // Create a simple streaming channel +//! let (tx, rx) = channel(); +//! thread::spawn(move|| { +//! tx.send(10).unwrap(); +//! }); +//! assert_eq!(rx.recv().unwrap(), 10); +//! ``` +//! +//! Shared usage: +//! +//! ``` +//! use std::thread; +//! use std::sync::mpsc::channel; +//! +//! // Create a shared channel that can be sent along from many threads +//! // where tx is the sending half (tx for transmission), and rx is the receiving +//! // half (rx for receiving). +//! let (tx, rx) = channel(); +//! for i in 0..10 { +//! let tx = tx.clone(); +//! thread::spawn(move|| { +//! tx.send(i).unwrap(); +//! }); +//! } +//! +//! for _ in 0..10 { +//! let j = rx.recv().unwrap(); +//! assert!(0 <= j && j < 10); +//! } +//! ``` +//! +//! Propagating panics: +//! +//! ``` +//! use std::sync::mpsc::channel; +//! +//! // The call to recv() will return an error because the channel has already +//! // hung up (or been deallocated) +//! let (tx, rx) = channel::(); +//! drop(tx); +//! assert!(rx.recv().is_err()); +//! ``` +//! +//! Synchronous channels: +//! +//! ``` +//! use std::thread; +//! use std::sync::mpsc::sync_channel; +//! +//! let (tx, rx) = sync_channel::(0); +//! thread::spawn(move|| { +//! // This will wait for the parent thread to start receiving +//! tx.send(53).unwrap(); +//! }); +//! rx.recv().unwrap(); +//! ``` + +#![stable(feature = "rust1", since = "1.0.0")] + +// A description of how Rust's channel implementation works +// +// Channels are supposed to be the basic building block for all other +// concurrent primitives that are used in Rust. As a result, the channel type +// needs to be highly optimized, flexible, and broad enough for use everywhere. +// +// The choice of implementation of all channels is to be built on lock-free data +// structures. The channels themselves are then consequently also lock-free data +// structures. As always with lock-free code, this is a very "here be dragons" +// territory, especially because I'm unaware of any academic papers that have +// gone into great length about channels of these flavors. +// +// ## Flavors of channels +// +// From the perspective of a consumer of this library, there is only one flavor +// of channel. This channel can be used as a stream and cloned to allow multiple +// senders. Under the hood, however, there are actually three flavors of +// channels in play. +// +// * Flavor::Oneshots - these channels are highly optimized for the one-send use +// case. They contain as few atomics as possible and +// involve one and exactly one allocation. +// * Streams - these channels are optimized for the non-shared use case. They +// use a different concurrent queue that is more tailored for this +// use case. The initial allocation of this flavor of channel is not +// optimized. +// * Shared - this is the most general form of channel that this module offers, +// a channel with multiple senders. This type is as optimized as it +// can be, but the previous two types mentioned are much faster for +// their use-cases. +// +// ## Concurrent queues +// +// The basic idea of Rust's Sender/Receiver types is that send() never blocks, +// but recv() obviously blocks. This means that under the hood there must be +// some shared and concurrent queue holding all of the actual data. +// +// With two flavors of channels, two flavors of queues are also used. We have +// chosen to use queues from a well-known author that are abbreviated as SPSC +// and MPSC (single producer, single consumer and multiple producer, single +// consumer). SPSC queues are used for streams while MPSC queues are used for +// shared channels. +// +// ### SPSC optimizations +// +// The SPSC queue found online is essentially a linked list of nodes where one +// half of the nodes are the "queue of data" and the other half of nodes are a +// cache of unused nodes. The unused nodes are used such that an allocation is +// not required on every push() and a free doesn't need to happen on every +// pop(). +// +// As found online, however, the cache of nodes is of an infinite size. This +// means that if a channel at one point in its life had 50k items in the queue, +// then the queue will always have the capacity for 50k items. I believed that +// this was an unnecessary limitation of the implementation, so I have altered +// the queue to optionally have a bound on the cache size. +// +// By default, streams will have an unbounded SPSC queue with a small-ish cache +// size. The hope is that the cache is still large enough to have very fast +// send() operations while not too large such that millions of channels can +// coexist at once. +// +// ### MPSC optimizations +// +// Right now the MPSC queue has not been optimized. Like the SPSC queue, it uses +// a linked list under the hood to earn its unboundedness, but I have not put +// forth much effort into having a cache of nodes similar to the SPSC queue. +// +// For now, I believe that this is "ok" because shared channels are not the most +// common type, but soon we may wish to revisit this queue choice and determine +// another candidate for backend storage of shared channels. +// +// ## Overview of the Implementation +// +// Now that there's a little background on the concurrent queues used, it's +// worth going into much more detail about the channels themselves. The basic +// pseudocode for a send/recv are: +// +// +// send(t) recv() +// queue.push(t) return if queue.pop() +// if increment() == -1 deschedule { +// wakeup() if decrement() > 0 +// cancel_deschedule() +// } +// queue.pop() +// +// As mentioned before, there are no locks in this implementation, only atomic +// instructions are used. +// +// ### The internal atomic counter +// +// Every channel has a shared counter with each half to keep track of the size +// of the queue. This counter is used to abort descheduling by the receiver and +// to know when to wake up on the sending side. +// +// As seen in the pseudocode, senders will increment this count and receivers +// will decrement the count. The theory behind this is that if a sender sees a +// -1 count, it will wake up the receiver, and if the receiver sees a 1+ count, +// then it doesn't need to block. +// +// The recv() method has a beginning call to pop(), and if successful, it needs +// to decrement the count. It is a crucial implementation detail that this +// decrement does *not* happen to the shared counter. If this were the case, +// then it would be possible for the counter to be very negative when there were +// no receivers waiting, in which case the senders would have to determine when +// it was actually appropriate to wake up a receiver. +// +// Instead, the "steal count" is kept track of separately (not atomically +// because it's only used by receivers), and then the decrement() call when +// descheduling will lump in all of the recent steals into one large decrement. +// +// The implication of this is that if a sender sees a -1 count, then there's +// guaranteed to be a waiter waiting! +// +// ## Native Implementation +// +// A major goal of these channels is to work seamlessly on and off the runtime. +// All of the previous race conditions have been worded in terms of +// scheduler-isms (which is obviously not available without the runtime). +// +// For now, native usage of channels (off the runtime) will fall back onto +// mutexes/cond vars for descheduling/atomic decisions. The no-contention path +// is still entirely lock-free, the "deschedule" blocks above are surrounded by +// a mutex and the "wakeup" blocks involve grabbing a mutex and signaling on a +// condition variable. +// +// ## Select +// +// Being able to support selection over channels has greatly influenced this +// design, and not only does selection need to work inside the runtime, but also +// outside the runtime. +// +// The implementation is fairly straightforward. The goal of select() is not to +// return some data, but only to return which channel can receive data without +// blocking. The implementation is essentially the entire blocking procedure +// followed by an increment as soon as its woken up. The cancellation procedure +// involves an increment and swapping out of to_wake to acquire ownership of the +// thread to unblock. +// +// Sadly this current implementation requires multiple allocations, so I have +// seen the throughput of select() be much worse than it should be. I do not +// believe that there is anything fundamental that needs to change about these +// channels, however, in order to support a more efficient select(). +// +// # Conclusion +// +// And now that you've seen all the races that I found and attempted to fix, +// here's the code for you to find some more! + +use sync::Arc; +use error; +use fmt; +use mem; +use cell::UnsafeCell; +use time::{Duration, Instant}; + +#[unstable(feature = "mpsc_select", issue = "27800")] +pub use self::select::{Select, Handle}; +use self::select::StartResult; +use self::select::StartResult::*; +use self::blocking::SignalToken; + +mod blocking; +mod oneshot; +mod select; +mod shared; +mod stream; +mod sync; +mod mpsc_queue; +mod spsc_queue; + +/// The receiving-half of Rust's channel type. This half can only be owned by +/// one thread +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Receiver { + inner: UnsafeCell>, +} + +// The receiver port can be sent from place to place, so long as it +// is not used to receive non-sendable things. +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl Send for Receiver { } + +#[stable(feature = "rust1", since = "1.0.0")] +impl !Sync for Receiver { } + +/// An iterator over messages on a receiver, this iterator will block +/// whenever `next` is called, waiting for a new message, and `None` will be +/// returned when the corresponding channel has hung up. +#[stable(feature = "rust1", since = "1.0.0")] +#[derive(Debug)] +pub struct Iter<'a, T: 'a> { + rx: &'a Receiver +} + +/// An iterator that attempts to yield all pending values for a receiver. +/// `None` will be returned when there are no pending values remaining or +/// if the corresponding channel has hung up. +/// +/// This Iterator will never block the caller in order to wait for data to +/// become available. Instead, it will return `None`. +#[stable(feature = "receiver_try_iter", since = "1.15.0")] +#[derive(Debug)] +pub struct TryIter<'a, T: 'a> { + rx: &'a Receiver +} + +/// An owning iterator over messages on a receiver, this iterator will block +/// whenever `next` is called, waiting for a new message, and `None` will be +/// returned when the corresponding channel has hung up. +#[stable(feature = "receiver_into_iter", since = "1.1.0")] +#[derive(Debug)] +pub struct IntoIter { + rx: Receiver +} + +/// The sending-half of Rust's asynchronous channel type. This half can only be +/// owned by one thread, but it can be cloned to send to other threads. +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Sender { + inner: UnsafeCell>, +} + +// The send port can be sent from place to place, so long as it +// is not used to send non-sendable things. +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl Send for Sender { } + +#[stable(feature = "rust1", since = "1.0.0")] +impl !Sync for Sender { } + +/// The sending-half of Rust's synchronous channel type. This half can only be +/// owned by one thread, but it can be cloned to send to other threads. +#[stable(feature = "rust1", since = "1.0.0")] +pub struct SyncSender { + inner: Arc>, +} + +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl Send for SyncSender {} + +#[stable(feature = "rust1", since = "1.0.0")] +impl !Sync for SyncSender {} + +/// An error returned from the `send` function on channels. +/// +/// A `send` operation can only fail if the receiving end of a channel is +/// disconnected, implying that the data could never be received. The error +/// contains the data being sent as a payload so it can be recovered. +#[stable(feature = "rust1", since = "1.0.0")] +#[derive(PartialEq, Eq, Clone, Copy)] +pub struct SendError(#[stable(feature = "rust1", since = "1.0.0")] pub T); + +/// An error returned from the `recv` function on a `Receiver`. +/// +/// The `recv` operation can only fail if the sending half of a channel is +/// disconnected, implying that no further messages will ever be received. +#[derive(PartialEq, Eq, Clone, Copy, Debug)] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RecvError; + +/// This enumeration is the list of the possible reasons that `try_recv` could +/// not return data when called. +#[derive(PartialEq, Eq, Clone, Copy, Debug)] +#[stable(feature = "rust1", since = "1.0.0")] +pub enum TryRecvError { + /// This channel is currently empty, but the sender(s) have not yet + /// disconnected, so data may yet become available. + #[stable(feature = "rust1", since = "1.0.0")] + Empty, + + /// This channel's sending half has become disconnected, and there will + /// never be any more data received on this channel + #[stable(feature = "rust1", since = "1.0.0")] + Disconnected, +} + +/// This enumeration is the list of possible errors that `recv_timeout` could +/// not return data when called. +#[derive(PartialEq, Eq, Clone, Copy, Debug)] +#[stable(feature = "mpsc_recv_timeout", since = "1.12.0")] +pub enum RecvTimeoutError { + /// This channel is currently empty, but the sender(s) have not yet + /// disconnected, so data may yet become available. + #[stable(feature = "mpsc_recv_timeout", since = "1.12.0")] + Timeout, + /// This channel's sending half has become disconnected, and there will + /// never be any more data received on this channel + #[stable(feature = "mpsc_recv_timeout", since = "1.12.0")] + Disconnected, +} + +/// This enumeration is the list of the possible error outcomes for the +/// `SyncSender::try_send` method. +#[stable(feature = "rust1", since = "1.0.0")] +#[derive(PartialEq, Eq, Clone, Copy)] +pub enum TrySendError { + /// The data could not be sent on the channel because it would require that + /// the callee block to send the data. + /// + /// If this is a buffered channel, then the buffer is full at this time. If + /// this is not a buffered channel, then there is no receiver available to + /// acquire the data. + #[stable(feature = "rust1", since = "1.0.0")] + Full(#[stable(feature = "rust1", since = "1.0.0")] T), + + /// This channel's receiving half has disconnected, so the data could not be + /// sent. The data is returned back to the callee in this case. + #[stable(feature = "rust1", since = "1.0.0")] + Disconnected(#[stable(feature = "rust1", since = "1.0.0")] T), +} + +enum Flavor { + Oneshot(Arc>), + Stream(Arc>), + Shared(Arc>), + Sync(Arc>), +} + +#[doc(hidden)] +trait UnsafeFlavor { + fn inner_unsafe(&self) -> &UnsafeCell>; + unsafe fn inner_mut(&self) -> &mut Flavor { + &mut *self.inner_unsafe().get() + } + unsafe fn inner(&self) -> &Flavor { + &*self.inner_unsafe().get() + } +} +impl UnsafeFlavor for Sender { + fn inner_unsafe(&self) -> &UnsafeCell> { + &self.inner + } +} +impl UnsafeFlavor for Receiver { + fn inner_unsafe(&self) -> &UnsafeCell> { + &self.inner + } +} + +/// Creates a new asynchronous channel, returning the sender/receiver halves. +/// All data sent on the sender will become available on the receiver, and no +/// send will block the calling thread (this channel has an "infinite buffer"). +/// +/// If the [`Receiver`] is disconnected while trying to [`send()`] with the +/// [`Sender`], the [`send()`] method will return an error. +/// +/// [`send()`]: ../../../std/sync/mpsc/struct.Sender.html#method.send +/// [`Sender`]: ../../../std/sync/mpsc/struct.Sender.html +/// [`Receiver`]: ../../../std/sync/mpsc/struct.Receiver.html +/// +/// # Examples +/// +/// ``` +/// use std::sync::mpsc::channel; +/// use std::thread; +/// +/// // tx is the sending half (tx for transmission), and rx is the receiving +/// // half (rx for receiving). +/// let (tx, rx) = channel(); +/// +/// // Spawn off an expensive computation +/// thread::spawn(move|| { +/// # fn expensive_computation() {} +/// tx.send(expensive_computation()).unwrap(); +/// }); +/// +/// // Do some useful work for awhile +/// +/// // Let's see what that answer was +/// println!("{:?}", rx.recv().unwrap()); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn channel() -> (Sender, Receiver) { + let a = Arc::new(oneshot::Packet::new()); + (Sender::new(Flavor::Oneshot(a.clone())), Receiver::new(Flavor::Oneshot(a))) +} + +/// Creates a new synchronous, bounded channel. +/// +/// Like asynchronous channels, the [`Receiver`] will block until a message +/// becomes available. These channels differ greatly in the semantics of the +/// sender from asynchronous channels, however. +/// +/// This channel has an internal buffer on which messages will be queued. +/// `bound` specifies the buffer size. When the internal buffer becomes full, +/// future sends will *block* waiting for the buffer to open up. Note that a +/// buffer size of 0 is valid, in which case this becomes "rendezvous channel" +/// where each [`send()`] will not return until a recv is paired with it. +/// +/// Like asynchronous channels, if the [`Receiver`] is disconnected while +/// trying to [`send()`] with the [`SyncSender`], the [`send()`] method will +/// return an error. +/// +/// [`send()`]: ../../../std/sync/mpsc/struct.SyncSender.html#method.send +/// [`SyncSender`]: ../../../std/sync/mpsc/struct.SyncSender.html +/// [`Receiver`]: ../../../std/sync/mpsc/struct.Receiver.html +/// +/// # Examples +/// +/// ``` +/// use std::sync::mpsc::sync_channel; +/// use std::thread; +/// +/// let (tx, rx) = sync_channel(1); +/// +/// // this returns immediately +/// tx.send(1).unwrap(); +/// +/// thread::spawn(move|| { +/// // this will block until the previous message has been received +/// tx.send(2).unwrap(); +/// }); +/// +/// assert_eq!(rx.recv().unwrap(), 1); +/// assert_eq!(rx.recv().unwrap(), 2); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn sync_channel(bound: usize) -> (SyncSender, Receiver) { + let a = Arc::new(sync::Packet::new(bound)); + (SyncSender::new(a.clone()), Receiver::new(Flavor::Sync(a))) +} + +//////////////////////////////////////////////////////////////////////////////// +// Sender +//////////////////////////////////////////////////////////////////////////////// + +impl Sender { + fn new(inner: Flavor) -> Sender { + Sender { + inner: UnsafeCell::new(inner), + } + } + + /// Attempts to send a value on this channel, returning it back if it could + /// not be sent. + /// + /// A successful send occurs when it is determined that the other end of + /// the channel has not hung up already. An unsuccessful send would be one + /// where the corresponding receiver has already been deallocated. Note + /// that a return value of `Err` means that the data will never be + /// received, but a return value of `Ok` does *not* mean that the data + /// will be received. It is possible for the corresponding receiver to + /// hang up immediately after this function returns `Ok`. + /// + /// This method will never block the current thread. + /// + /// # Examples + /// + /// ``` + /// use std::sync::mpsc::channel; + /// + /// let (tx, rx) = channel(); + /// + /// // This send is always successful + /// tx.send(1).unwrap(); + /// + /// // This send will fail because the receiver is gone + /// drop(rx); + /// assert_eq!(tx.send(1).unwrap_err().0, 1); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn send(&self, t: T) -> Result<(), SendError> { + let (new_inner, ret) = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => { + if !p.sent() { + return p.send(t).map_err(SendError); + } else { + let a = Arc::new(stream::Packet::new()); + let rx = Receiver::new(Flavor::Stream(a.clone())); + match p.upgrade(rx) { + oneshot::UpSuccess => { + let ret = a.send(t); + (a, ret) + } + oneshot::UpDisconnected => (a, Err(t)), + oneshot::UpWoke(token) => { + // This send cannot panic because the thread is + // asleep (we're looking at it), so the receiver + // can't go away. + a.send(t).ok().unwrap(); + token.signal(); + (a, Ok(())) + } + } + } + } + Flavor::Stream(ref p) => return p.send(t).map_err(SendError), + Flavor::Shared(ref p) => return p.send(t).map_err(SendError), + Flavor::Sync(..) => unreachable!(), + }; + + unsafe { + let tmp = Sender::new(Flavor::Stream(new_inner)); + mem::swap(self.inner_mut(), tmp.inner_mut()); + } + ret.map_err(SendError) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Clone for Sender { + fn clone(&self) -> Sender { + let packet = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => { + let a = Arc::new(shared::Packet::new()); + { + let guard = a.postinit_lock(); + let rx = Receiver::new(Flavor::Shared(a.clone())); + let sleeper = match p.upgrade(rx) { + oneshot::UpSuccess | + oneshot::UpDisconnected => None, + oneshot::UpWoke(task) => Some(task), + }; + a.inherit_blocker(sleeper, guard); + } + a + } + Flavor::Stream(ref p) => { + let a = Arc::new(shared::Packet::new()); + { + let guard = a.postinit_lock(); + let rx = Receiver::new(Flavor::Shared(a.clone())); + let sleeper = match p.upgrade(rx) { + stream::UpSuccess | + stream::UpDisconnected => None, + stream::UpWoke(task) => Some(task), + }; + a.inherit_blocker(sleeper, guard); + } + a + } + Flavor::Shared(ref p) => { + p.clone_chan(); + return Sender::new(Flavor::Shared(p.clone())); + } + Flavor::Sync(..) => unreachable!(), + }; + + unsafe { + let tmp = Sender::new(Flavor::Shared(packet.clone())); + mem::swap(self.inner_mut(), tmp.inner_mut()); + } + Sender::new(Flavor::Shared(packet)) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Drop for Sender { + fn drop(&mut self) { + match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => p.drop_chan(), + Flavor::Stream(ref p) => p.drop_chan(), + Flavor::Shared(ref p) => p.drop_chan(), + Flavor::Sync(..) => unreachable!(), + } + } +} + +#[stable(feature = "mpsc_debug", since = "1.7.0")] +impl fmt::Debug for Sender { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!(f, "Sender {{ .. }}") + } +} + +//////////////////////////////////////////////////////////////////////////////// +// SyncSender +//////////////////////////////////////////////////////////////////////////////// + +impl SyncSender { + fn new(inner: Arc>) -> SyncSender { + SyncSender { inner: inner } + } + + /// Sends a value on this synchronous channel. + /// + /// This function will *block* until space in the internal buffer becomes + /// available or a receiver is available to hand off the message to. + /// + /// Note that a successful send does *not* guarantee that the receiver will + /// ever see the data if there is a buffer on this channel. Items may be + /// enqueued in the internal buffer for the receiver to receive at a later + /// time. If the buffer size is 0, however, it can be guaranteed that the + /// receiver has indeed received the data if this function returns success. + /// + /// This function will never panic, but it may return `Err` if the + /// `Receiver` has disconnected and is no longer able to receive + /// information. + #[stable(feature = "rust1", since = "1.0.0")] + pub fn send(&self, t: T) -> Result<(), SendError> { + self.inner.send(t).map_err(SendError) + } + + /// Attempts to send a value on this channel without blocking. + /// + /// This method differs from `send` by returning immediately if the + /// channel's buffer is full or no receiver is waiting to acquire some + /// data. Compared with `send`, this function has two failure cases + /// instead of one (one for disconnection, one for a full buffer). + /// + /// See `SyncSender::send` for notes about guarantees of whether the + /// receiver has received the data or not if this function is successful. + #[stable(feature = "rust1", since = "1.0.0")] + pub fn try_send(&self, t: T) -> Result<(), TrySendError> { + self.inner.try_send(t) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Clone for SyncSender { + fn clone(&self) -> SyncSender { + self.inner.clone_chan(); + SyncSender::new(self.inner.clone()) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Drop for SyncSender { + fn drop(&mut self) { + self.inner.drop_chan(); + } +} + +#[stable(feature = "mpsc_debug", since = "1.7.0")] +impl fmt::Debug for SyncSender { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!(f, "SyncSender {{ .. }}") + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Receiver +//////////////////////////////////////////////////////////////////////////////// + +impl Receiver { + fn new(inner: Flavor) -> Receiver { + Receiver { inner: UnsafeCell::new(inner) } + } + + /// Attempts to return a pending value on this receiver without blocking + /// + /// This method will never block the caller in order to wait for data to + /// become available. Instead, this will always return immediately with a + /// possible option of pending data on the channel. + /// + /// This is useful for a flavor of "optimistic check" before deciding to + /// block on a receiver. + #[stable(feature = "rust1", since = "1.0.0")] + pub fn try_recv(&self) -> Result { + loop { + let new_port = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => { + match p.try_recv() { + Ok(t) => return Ok(t), + Err(oneshot::Empty) => return Err(TryRecvError::Empty), + Err(oneshot::Disconnected) => { + return Err(TryRecvError::Disconnected) + } + Err(oneshot::Upgraded(rx)) => rx, + } + } + Flavor::Stream(ref p) => { + match p.try_recv() { + Ok(t) => return Ok(t), + Err(stream::Empty) => return Err(TryRecvError::Empty), + Err(stream::Disconnected) => { + return Err(TryRecvError::Disconnected) + } + Err(stream::Upgraded(rx)) => rx, + } + } + Flavor::Shared(ref p) => { + match p.try_recv() { + Ok(t) => return Ok(t), + Err(shared::Empty) => return Err(TryRecvError::Empty), + Err(shared::Disconnected) => { + return Err(TryRecvError::Disconnected) + } + } + } + Flavor::Sync(ref p) => { + match p.try_recv() { + Ok(t) => return Ok(t), + Err(sync::Empty) => return Err(TryRecvError::Empty), + Err(sync::Disconnected) => { + return Err(TryRecvError::Disconnected) + } + } + } + }; + unsafe { + mem::swap(self.inner_mut(), + new_port.inner_mut()); + } + } + } + + /// Attempts to wait for a value on this receiver, returning an error if the + /// corresponding channel has hung up. + /// + /// This function will always block the current thread if there is no data + /// available and it's possible for more data to be sent. Once a message is + /// sent to the corresponding `Sender`, then this receiver will wake up and + /// return that message. + /// + /// If the corresponding `Sender` has disconnected, or it disconnects while + /// this call is blocking, this call will wake up and return `Err` to + /// indicate that no more messages can ever be received on this channel. + /// However, since channels are buffered, messages sent before the disconnect + /// will still be properly received. + /// + /// # Examples + /// + /// ``` + /// use std::sync::mpsc; + /// use std::thread; + /// + /// let (send, recv) = mpsc::channel(); + /// let handle = thread::spawn(move || { + /// send.send(1u8).unwrap(); + /// }); + /// + /// handle.join().unwrap(); + /// + /// assert_eq!(Ok(1), recv.recv()); + /// ``` + /// + /// Buffering behavior: + /// + /// ``` + /// use std::sync::mpsc; + /// use std::thread; + /// use std::sync::mpsc::RecvError; + /// + /// let (send, recv) = mpsc::channel(); + /// let handle = thread::spawn(move || { + /// send.send(1u8).unwrap(); + /// send.send(2).unwrap(); + /// send.send(3).unwrap(); + /// drop(send); + /// }); + /// + /// // wait for the thread to join so we ensure the sender is dropped + /// handle.join().unwrap(); + /// + /// assert_eq!(Ok(1), recv.recv()); + /// assert_eq!(Ok(2), recv.recv()); + /// assert_eq!(Ok(3), recv.recv()); + /// assert_eq!(Err(RecvError), recv.recv()); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn recv(&self) -> Result { + loop { + let new_port = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => { + match p.recv(None) { + Ok(t) => return Ok(t), + Err(oneshot::Disconnected) => return Err(RecvError), + Err(oneshot::Upgraded(rx)) => rx, + Err(oneshot::Empty) => unreachable!(), + } + } + Flavor::Stream(ref p) => { + match p.recv(None) { + Ok(t) => return Ok(t), + Err(stream::Disconnected) => return Err(RecvError), + Err(stream::Upgraded(rx)) => rx, + Err(stream::Empty) => unreachable!(), + } + } + Flavor::Shared(ref p) => { + match p.recv(None) { + Ok(t) => return Ok(t), + Err(shared::Disconnected) => return Err(RecvError), + Err(shared::Empty) => unreachable!(), + } + } + Flavor::Sync(ref p) => return p.recv(None).map_err(|_| RecvError), + }; + unsafe { + mem::swap(self.inner_mut(), new_port.inner_mut()); + } + } + } + + /// Attempts to wait for a value on this receiver, returning an error if the + /// corresponding channel has hung up, or if it waits more than `timeout`. + /// + /// This function will always block the current thread if there is no data + /// available and it's possible for more data to be sent. Once a message is + /// sent to the corresponding `Sender`, then this receiver will wake up and + /// return that message. + /// + /// If the corresponding `Sender` has disconnected, or it disconnects while + /// this call is blocking, this call will wake up and return `Err` to + /// indicate that no more messages can ever be received on this channel. + /// However, since channels are buffered, messages sent before the disconnect + /// will still be properly received. + /// + /// # Examples + /// + /// ```no_run + /// use std::sync::mpsc::{self, RecvTimeoutError}; + /// use std::time::Duration; + /// + /// let (send, recv) = mpsc::channel::<()>(); + /// + /// let timeout = Duration::from_millis(100); + /// assert_eq!(Err(RecvTimeoutError::Timeout), recv.recv_timeout(timeout)); + /// ``` + #[stable(feature = "mpsc_recv_timeout", since = "1.12.0")] + pub fn recv_timeout(&self, timeout: Duration) -> Result { + // Do an optimistic try_recv to avoid the performance impact of + // Instant::now() in the full-channel case. + match self.try_recv() { + Ok(result) + => Ok(result), + Err(TryRecvError::Disconnected) + => Err(RecvTimeoutError::Disconnected), + Err(TryRecvError::Empty) + => self.recv_max_until(Instant::now() + timeout) + } + } + + fn recv_max_until(&self, deadline: Instant) -> Result { + use self::RecvTimeoutError::*; + + loop { + let port_or_empty = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => { + match p.recv(Some(deadline)) { + Ok(t) => return Ok(t), + Err(oneshot::Disconnected) => return Err(Disconnected), + Err(oneshot::Upgraded(rx)) => Some(rx), + Err(oneshot::Empty) => None, + } + } + Flavor::Stream(ref p) => { + match p.recv(Some(deadline)) { + Ok(t) => return Ok(t), + Err(stream::Disconnected) => return Err(Disconnected), + Err(stream::Upgraded(rx)) => Some(rx), + Err(stream::Empty) => None, + } + } + Flavor::Shared(ref p) => { + match p.recv(Some(deadline)) { + Ok(t) => return Ok(t), + Err(shared::Disconnected) => return Err(Disconnected), + Err(shared::Empty) => None, + } + } + Flavor::Sync(ref p) => { + match p.recv(Some(deadline)) { + Ok(t) => return Ok(t), + Err(sync::Disconnected) => return Err(Disconnected), + Err(sync::Empty) => None, + } + } + }; + + if let Some(new_port) = port_or_empty { + unsafe { + mem::swap(self.inner_mut(), new_port.inner_mut()); + } + } + + // If we're already passed the deadline, and we're here without + // data, return a timeout, else try again. + if Instant::now() >= deadline { + return Err(Timeout); + } + } + } + + /// Returns an iterator that will block waiting for messages, but never + /// `panic!`. It will return `None` when the channel has hung up. + #[stable(feature = "rust1", since = "1.0.0")] + pub fn iter(&self) -> Iter { + Iter { rx: self } + } + + /// Returns an iterator that will attempt to yield all pending values. + /// It will return `None` if there are no more pending values or if the + /// channel has hung up. The iterator will never `panic!` or block the + /// user by waiting for values. + #[stable(feature = "receiver_try_iter", since = "1.15.0")] + pub fn try_iter(&self) -> TryIter { + TryIter { rx: self } + } + +} + +impl select::Packet for Receiver { + fn can_recv(&self) -> bool { + loop { + let new_port = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => { + match p.can_recv() { + Ok(ret) => return ret, + Err(upgrade) => upgrade, + } + } + Flavor::Stream(ref p) => { + match p.can_recv() { + Ok(ret) => return ret, + Err(upgrade) => upgrade, + } + } + Flavor::Shared(ref p) => return p.can_recv(), + Flavor::Sync(ref p) => return p.can_recv(), + }; + unsafe { + mem::swap(self.inner_mut(), + new_port.inner_mut()); + } + } + } + + fn start_selection(&self, mut token: SignalToken) -> StartResult { + loop { + let (t, new_port) = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => { + match p.start_selection(token) { + oneshot::SelSuccess => return Installed, + oneshot::SelCanceled => return Abort, + oneshot::SelUpgraded(t, rx) => (t, rx), + } + } + Flavor::Stream(ref p) => { + match p.start_selection(token) { + stream::SelSuccess => return Installed, + stream::SelCanceled => return Abort, + stream::SelUpgraded(t, rx) => (t, rx), + } + } + Flavor::Shared(ref p) => return p.start_selection(token), + Flavor::Sync(ref p) => return p.start_selection(token), + }; + token = t; + unsafe { + mem::swap(self.inner_mut(), new_port.inner_mut()); + } + } + } + + fn abort_selection(&self) -> bool { + let mut was_upgrade = false; + loop { + let result = match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => p.abort_selection(), + Flavor::Stream(ref p) => p.abort_selection(was_upgrade), + Flavor::Shared(ref p) => return p.abort_selection(was_upgrade), + Flavor::Sync(ref p) => return p.abort_selection(), + }; + let new_port = match result { Ok(b) => return b, Err(p) => p }; + was_upgrade = true; + unsafe { + mem::swap(self.inner_mut(), + new_port.inner_mut()); + } + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'a, T> Iterator for Iter<'a, T> { + type Item = T; + + fn next(&mut self) -> Option { self.rx.recv().ok() } +} + +#[stable(feature = "receiver_try_iter", since = "1.15.0")] +impl<'a, T> Iterator for TryIter<'a, T> { + type Item = T; + + fn next(&mut self) -> Option { self.rx.try_recv().ok() } +} + +#[stable(feature = "receiver_into_iter", since = "1.1.0")] +impl<'a, T> IntoIterator for &'a Receiver { + type Item = T; + type IntoIter = Iter<'a, T>; + + fn into_iter(self) -> Iter<'a, T> { self.iter() } +} + +#[stable(feature = "receiver_into_iter", since = "1.1.0")] +impl Iterator for IntoIter { + type Item = T; + fn next(&mut self) -> Option { self.rx.recv().ok() } +} + +#[stable(feature = "receiver_into_iter", since = "1.1.0")] +impl IntoIterator for Receiver { + type Item = T; + type IntoIter = IntoIter; + + fn into_iter(self) -> IntoIter { + IntoIter { rx: self } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl Drop for Receiver { + fn drop(&mut self) { + match *unsafe { self.inner() } { + Flavor::Oneshot(ref p) => p.drop_port(), + Flavor::Stream(ref p) => p.drop_port(), + Flavor::Shared(ref p) => p.drop_port(), + Flavor::Sync(ref p) => p.drop_port(), + } + } +} + +#[stable(feature = "mpsc_debug", since = "1.7.0")] +impl fmt::Debug for Receiver { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!(f, "Receiver {{ .. }}") + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Debug for SendError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + "SendError(..)".fmt(f) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Display for SendError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + "sending on a closed channel".fmt(f) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl error::Error for SendError { + fn description(&self) -> &str { + "sending on a closed channel" + } + + fn cause(&self) -> Option<&error::Error> { + None + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Debug for TrySendError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match *self { + TrySendError::Full(..) => "Full(..)".fmt(f), + TrySendError::Disconnected(..) => "Disconnected(..)".fmt(f), + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Display for TrySendError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match *self { + TrySendError::Full(..) => { + "sending on a full channel".fmt(f) + } + TrySendError::Disconnected(..) => { + "sending on a closed channel".fmt(f) + } + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl error::Error for TrySendError { + + fn description(&self) -> &str { + match *self { + TrySendError::Full(..) => { + "sending on a full channel" + } + TrySendError::Disconnected(..) => { + "sending on a closed channel" + } + } + } + + fn cause(&self) -> Option<&error::Error> { + None + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Display for RecvError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + "receiving on a closed channel".fmt(f) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl error::Error for RecvError { + + fn description(&self) -> &str { + "receiving on a closed channel" + } + + fn cause(&self) -> Option<&error::Error> { + None + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Display for TryRecvError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match *self { + TryRecvError::Empty => { + "receiving on an empty channel".fmt(f) + } + TryRecvError::Disconnected => { + "receiving on a closed channel".fmt(f) + } + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl error::Error for TryRecvError { + + fn description(&self) -> &str { + match *self { + TryRecvError::Empty => { + "receiving on an empty channel" + } + TryRecvError::Disconnected => { + "receiving on a closed channel" + } + } + } + + fn cause(&self) -> Option<&error::Error> { + None + } +} + +#[stable(feature = "mpsc_recv_timeout_error", since = "1.14.0")] +impl fmt::Display for RecvTimeoutError { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match *self { + RecvTimeoutError::Timeout => { + "timed out waiting on channel".fmt(f) + } + RecvTimeoutError::Disconnected => { + "channel is empty and sending half is closed".fmt(f) + } + } + } +} + +#[stable(feature = "mpsc_recv_timeout_error", since = "1.14.0")] +impl error::Error for RecvTimeoutError { + fn description(&self) -> &str { + match *self { + RecvTimeoutError::Timeout => { + "timed out waiting on channel" + } + RecvTimeoutError::Disconnected => { + "channel is empty and sending half is closed" + } + } + } + + fn cause(&self) -> Option<&error::Error> { + None + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use env; + use super::*; + use thread; + use time::{Duration, Instant}; + + pub fn stress_factor() -> usize { + match env::var("RUST_TEST_STRESS") { + Ok(val) => val.parse().unwrap(), + Err(..) => 1, + } + } + + #[test] + fn smoke() { + let (tx, rx) = channel::(); + tx.send(1).unwrap(); + assert_eq!(rx.recv().unwrap(), 1); + } + + #[test] + fn drop_full() { + let (tx, _rx) = channel::>(); + tx.send(box 1).unwrap(); + } + + #[test] + fn drop_full_shared() { + let (tx, _rx) = channel::>(); + drop(tx.clone()); + drop(tx.clone()); + tx.send(box 1).unwrap(); + } + + #[test] + fn smoke_shared() { + let (tx, rx) = channel::(); + tx.send(1).unwrap(); + assert_eq!(rx.recv().unwrap(), 1); + let tx = tx.clone(); + tx.send(1).unwrap(); + assert_eq!(rx.recv().unwrap(), 1); + } + + #[test] + fn smoke_threads() { + let (tx, rx) = channel::(); + let _t = thread::spawn(move|| { + tx.send(1).unwrap(); + }); + assert_eq!(rx.recv().unwrap(), 1); + } + + #[test] + fn smoke_port_gone() { + let (tx, rx) = channel::(); + drop(rx); + assert!(tx.send(1).is_err()); + } + + #[test] + fn smoke_shared_port_gone() { + let (tx, rx) = channel::(); + drop(rx); + assert!(tx.send(1).is_err()) + } + + #[test] + fn smoke_shared_port_gone2() { + let (tx, rx) = channel::(); + drop(rx); + let tx2 = tx.clone(); + drop(tx); + assert!(tx2.send(1).is_err()); + } + + #[test] + fn port_gone_concurrent() { + let (tx, rx) = channel::(); + let _t = thread::spawn(move|| { + rx.recv().unwrap(); + }); + while tx.send(1).is_ok() {} + } + + #[test] + fn port_gone_concurrent_shared() { + let (tx, rx) = channel::(); + let tx2 = tx.clone(); + let _t = thread::spawn(move|| { + rx.recv().unwrap(); + }); + while tx.send(1).is_ok() && tx2.send(1).is_ok() {} + } + + #[test] + fn smoke_chan_gone() { + let (tx, rx) = channel::(); + drop(tx); + assert!(rx.recv().is_err()); + } + + #[test] + fn smoke_chan_gone_shared() { + let (tx, rx) = channel::<()>(); + let tx2 = tx.clone(); + drop(tx); + drop(tx2); + assert!(rx.recv().is_err()); + } + + #[test] + fn chan_gone_concurrent() { + let (tx, rx) = channel::(); + let _t = thread::spawn(move|| { + tx.send(1).unwrap(); + tx.send(1).unwrap(); + }); + while rx.recv().is_ok() {} + } + + #[test] + fn stress() { + let (tx, rx) = channel::(); + let t = thread::spawn(move|| { + for _ in 0..10000 { tx.send(1).unwrap(); } + }); + for _ in 0..10000 { + assert_eq!(rx.recv().unwrap(), 1); + } + t.join().ok().unwrap(); + } + + #[test] + fn stress_shared() { + const AMT: u32 = 10000; + const NTHREADS: u32 = 8; + let (tx, rx) = channel::(); + + let t = thread::spawn(move|| { + for _ in 0..AMT * NTHREADS { + assert_eq!(rx.recv().unwrap(), 1); + } + match rx.try_recv() { + Ok(..) => panic!(), + _ => {} + } + }); + + for _ in 0..NTHREADS { + let tx = tx.clone(); + thread::spawn(move|| { + for _ in 0..AMT { tx.send(1).unwrap(); } + }); + } + drop(tx); + t.join().ok().unwrap(); + } + + #[test] + fn send_from_outside_runtime() { + let (tx1, rx1) = channel::<()>(); + let (tx2, rx2) = channel::(); + let t1 = thread::spawn(move|| { + tx1.send(()).unwrap(); + for _ in 0..40 { + assert_eq!(rx2.recv().unwrap(), 1); + } + }); + rx1.recv().unwrap(); + let t2 = thread::spawn(move|| { + for _ in 0..40 { + tx2.send(1).unwrap(); + } + }); + t1.join().ok().unwrap(); + t2.join().ok().unwrap(); + } + + #[test] + fn recv_from_outside_runtime() { + let (tx, rx) = channel::(); + let t = thread::spawn(move|| { + for _ in 0..40 { + assert_eq!(rx.recv().unwrap(), 1); + } + }); + for _ in 0..40 { + tx.send(1).unwrap(); + } + t.join().ok().unwrap(); + } + + #[test] + fn no_runtime() { + let (tx1, rx1) = channel::(); + let (tx2, rx2) = channel::(); + let t1 = thread::spawn(move|| { + assert_eq!(rx1.recv().unwrap(), 1); + tx2.send(2).unwrap(); + }); + let t2 = thread::spawn(move|| { + tx1.send(1).unwrap(); + assert_eq!(rx2.recv().unwrap(), 2); + }); + t1.join().ok().unwrap(); + t2.join().ok().unwrap(); + } + + #[test] + fn oneshot_single_thread_close_port_first() { + // Simple test of closing without sending + let (_tx, rx) = channel::(); + drop(rx); + } + + #[test] + fn oneshot_single_thread_close_chan_first() { + // Simple test of closing without sending + let (tx, _rx) = channel::(); + drop(tx); + } + + #[test] + fn oneshot_single_thread_send_port_close() { + // Testing that the sender cleans up the payload if receiver is closed + let (tx, rx) = channel::>(); + drop(rx); + assert!(tx.send(box 0).is_err()); + } + + #[test] + fn oneshot_single_thread_recv_chan_close() { + // Receiving on a closed chan will panic + let res = thread::spawn(move|| { + let (tx, rx) = channel::(); + drop(tx); + rx.recv().unwrap(); + }).join(); + // What is our res? + assert!(res.is_err()); + } + + #[test] + fn oneshot_single_thread_send_then_recv() { + let (tx, rx) = channel::>(); + tx.send(box 10).unwrap(); + assert!(rx.recv().unwrap() == box 10); + } + + #[test] + fn oneshot_single_thread_try_send_open() { + let (tx, rx) = channel::(); + assert!(tx.send(10).is_ok()); + assert!(rx.recv().unwrap() == 10); + } + + #[test] + fn oneshot_single_thread_try_send_closed() { + let (tx, rx) = channel::(); + drop(rx); + assert!(tx.send(10).is_err()); + } + + #[test] + fn oneshot_single_thread_try_recv_open() { + let (tx, rx) = channel::(); + tx.send(10).unwrap(); + assert!(rx.recv() == Ok(10)); + } + + #[test] + fn oneshot_single_thread_try_recv_closed() { + let (tx, rx) = channel::(); + drop(tx); + assert!(rx.recv().is_err()); + } + + #[test] + fn oneshot_single_thread_peek_data() { + let (tx, rx) = channel::(); + assert_eq!(rx.try_recv(), Err(TryRecvError::Empty)); + tx.send(10).unwrap(); + assert_eq!(rx.try_recv(), Ok(10)); + } + + #[test] + fn oneshot_single_thread_peek_close() { + let (tx, rx) = channel::(); + drop(tx); + assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected)); + assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected)); + } + + #[test] + fn oneshot_single_thread_peek_open() { + let (_tx, rx) = channel::(); + assert_eq!(rx.try_recv(), Err(TryRecvError::Empty)); + } + + #[test] + fn oneshot_multi_task_recv_then_send() { + let (tx, rx) = channel::>(); + let _t = thread::spawn(move|| { + assert!(rx.recv().unwrap() == box 10); + }); + + tx.send(box 10).unwrap(); + } + + #[test] + fn oneshot_multi_task_recv_then_close() { + let (tx, rx) = channel::>(); + let _t = thread::spawn(move|| { + drop(tx); + }); + let res = thread::spawn(move|| { + assert!(rx.recv().unwrap() == box 10); + }).join(); + assert!(res.is_err()); + } + + #[test] + fn oneshot_multi_thread_close_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = channel::(); + let _t = thread::spawn(move|| { + drop(rx); + }); + drop(tx); + } + } + + #[test] + fn oneshot_multi_thread_send_close_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = channel::(); + let _t = thread::spawn(move|| { + drop(rx); + }); + let _ = thread::spawn(move|| { + tx.send(1).unwrap(); + }).join(); + } + } + + #[test] + fn oneshot_multi_thread_recv_close_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = channel::(); + thread::spawn(move|| { + let res = thread::spawn(move|| { + rx.recv().unwrap(); + }).join(); + assert!(res.is_err()); + }); + let _t = thread::spawn(move|| { + thread::spawn(move|| { + drop(tx); + }); + }); + } + } + + #[test] + fn oneshot_multi_thread_send_recv_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = channel::>(); + let _t = thread::spawn(move|| { + tx.send(box 10).unwrap(); + }); + assert!(rx.recv().unwrap() == box 10); + } + } + + #[test] + fn stream_send_recv_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = channel(); + + send(tx, 0); + recv(rx, 0); + + fn send(tx: Sender>, i: i32) { + if i == 10 { return } + + thread::spawn(move|| { + tx.send(box i).unwrap(); + send(tx, i + 1); + }); + } + + fn recv(rx: Receiver>, i: i32) { + if i == 10 { return } + + thread::spawn(move|| { + assert!(rx.recv().unwrap() == box i); + recv(rx, i + 1); + }); + } + } + } + + #[test] + fn oneshot_single_thread_recv_timeout() { + let (tx, rx) = channel(); + tx.send(()).unwrap(); + assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(())); + assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Err(RecvTimeoutError::Timeout)); + tx.send(()).unwrap(); + assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(())); + } + + #[test] + fn stress_recv_timeout_two_threads() { + let (tx, rx) = channel(); + let stress = stress_factor() + 100; + let timeout = Duration::from_millis(100); + + thread::spawn(move || { + for i in 0..stress { + if i % 2 == 0 { + thread::sleep(timeout * 2); + } + tx.send(1usize).unwrap(); + } + }); + + let mut recv_count = 0; + loop { + match rx.recv_timeout(timeout) { + Ok(n) => { + assert_eq!(n, 1usize); + recv_count += 1; + } + Err(RecvTimeoutError::Timeout) => continue, + Err(RecvTimeoutError::Disconnected) => break, + } + } + + assert_eq!(recv_count, stress); + } + + #[test] + fn recv_timeout_upgrade() { + let (tx, rx) = channel::<()>(); + let timeout = Duration::from_millis(1); + let _tx_clone = tx.clone(); + + let start = Instant::now(); + assert_eq!(rx.recv_timeout(timeout), Err(RecvTimeoutError::Timeout)); + assert!(Instant::now() >= start + timeout); + } + + #[test] + fn stress_recv_timeout_shared() { + let (tx, rx) = channel(); + let stress = stress_factor() + 100; + + for i in 0..stress { + let tx = tx.clone(); + thread::spawn(move || { + thread::sleep(Duration::from_millis(i as u64 * 10)); + tx.send(1usize).unwrap(); + }); + } + + drop(tx); + + let mut recv_count = 0; + loop { + match rx.recv_timeout(Duration::from_millis(10)) { + Ok(n) => { + assert_eq!(n, 1usize); + recv_count += 1; + } + Err(RecvTimeoutError::Timeout) => continue, + Err(RecvTimeoutError::Disconnected) => break, + } + } + + assert_eq!(recv_count, stress); + } + + #[test] + fn recv_a_lot() { + // Regression test that we don't run out of stack in scheduler context + let (tx, rx) = channel(); + for _ in 0..10000 { tx.send(()).unwrap(); } + for _ in 0..10000 { rx.recv().unwrap(); } + } + + #[test] + fn shared_recv_timeout() { + let (tx, rx) = channel(); + let total = 5; + for _ in 0..total { + let tx = tx.clone(); + thread::spawn(move|| { + tx.send(()).unwrap(); + }); + } + + for _ in 0..total { rx.recv().unwrap(); } + + assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Err(RecvTimeoutError::Timeout)); + tx.send(()).unwrap(); + assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(())); + } + + #[test] + fn shared_chan_stress() { + let (tx, rx) = channel(); + let total = stress_factor() + 100; + for _ in 0..total { + let tx = tx.clone(); + thread::spawn(move|| { + tx.send(()).unwrap(); + }); + } + + for _ in 0..total { + rx.recv().unwrap(); + } + } + + #[test] + fn test_nested_recv_iter() { + let (tx, rx) = channel::(); + let (total_tx, total_rx) = channel::(); + + let _t = thread::spawn(move|| { + let mut acc = 0; + for x in rx.iter() { + acc += x; + } + total_tx.send(acc).unwrap(); + }); + + tx.send(3).unwrap(); + tx.send(1).unwrap(); + tx.send(2).unwrap(); + drop(tx); + assert_eq!(total_rx.recv().unwrap(), 6); + } + + #[test] + fn test_recv_iter_break() { + let (tx, rx) = channel::(); + let (count_tx, count_rx) = channel(); + + let _t = thread::spawn(move|| { + let mut count = 0; + for x in rx.iter() { + if count >= 3 { + break; + } else { + count += x; + } + } + count_tx.send(count).unwrap(); + }); + + tx.send(2).unwrap(); + tx.send(2).unwrap(); + tx.send(2).unwrap(); + let _ = tx.send(2); + drop(tx); + assert_eq!(count_rx.recv().unwrap(), 4); + } + + #[test] + fn test_recv_try_iter() { + let (request_tx, request_rx) = channel(); + let (response_tx, response_rx) = channel(); + + // Request `x`s until we have `6`. + let t = thread::spawn(move|| { + let mut count = 0; + loop { + for x in response_rx.try_iter() { + count += x; + if count == 6 { + return count; + } + } + request_tx.send(()).unwrap(); + } + }); + + for _ in request_rx.iter() { + if response_tx.send(2).is_err() { + break; + } + } + + assert_eq!(t.join().unwrap(), 6); + } + + #[test] + fn test_recv_into_iter_owned() { + let mut iter = { + let (tx, rx) = channel::(); + tx.send(1).unwrap(); + tx.send(2).unwrap(); + + rx.into_iter() + }; + assert_eq!(iter.next().unwrap(), 1); + assert_eq!(iter.next().unwrap(), 2); + assert_eq!(iter.next().is_none(), true); + } + + #[test] + fn test_recv_into_iter_borrowed() { + let (tx, rx) = channel::(); + tx.send(1).unwrap(); + tx.send(2).unwrap(); + drop(tx); + let mut iter = (&rx).into_iter(); + assert_eq!(iter.next().unwrap(), 1); + assert_eq!(iter.next().unwrap(), 2); + assert_eq!(iter.next().is_none(), true); + } + + #[test] + fn try_recv_states() { + let (tx1, rx1) = channel::(); + let (tx2, rx2) = channel::<()>(); + let (tx3, rx3) = channel::<()>(); + let _t = thread::spawn(move|| { + rx2.recv().unwrap(); + tx1.send(1).unwrap(); + tx3.send(()).unwrap(); + rx2.recv().unwrap(); + drop(tx1); + tx3.send(()).unwrap(); + }); + + assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty)); + tx2.send(()).unwrap(); + rx3.recv().unwrap(); + assert_eq!(rx1.try_recv(), Ok(1)); + assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty)); + tx2.send(()).unwrap(); + rx3.recv().unwrap(); + assert_eq!(rx1.try_recv(), Err(TryRecvError::Disconnected)); + } + + // This bug used to end up in a livelock inside of the Receiver destructor + // because the internal state of the Shared packet was corrupted + #[test] + fn destroy_upgraded_shared_port_when_sender_still_active() { + let (tx, rx) = channel(); + let (tx2, rx2) = channel(); + let _t = thread::spawn(move|| { + rx.recv().unwrap(); // wait on a oneshot + drop(rx); // destroy a shared + tx2.send(()).unwrap(); + }); + // make sure the other thread has gone to sleep + for _ in 0..5000 { thread::yield_now(); } + + // upgrade to a shared chan and send a message + let t = tx.clone(); + drop(tx); + t.send(()).unwrap(); + + // wait for the child thread to exit before we exit + rx2.recv().unwrap(); + } + + #[test] + fn issue_32114() { + let (tx, _) = channel(); + let _ = tx.send(123); + assert_eq!(tx.send(123), Err(SendError(123))); + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod sync_tests { + use env; + use thread; + use super::*; + use time::Duration; + + pub fn stress_factor() -> usize { + match env::var("RUST_TEST_STRESS") { + Ok(val) => val.parse().unwrap(), + Err(..) => 1, + } + } + + #[test] + fn smoke() { + let (tx, rx) = sync_channel::(1); + tx.send(1).unwrap(); + assert_eq!(rx.recv().unwrap(), 1); + } + + #[test] + fn drop_full() { + let (tx, _rx) = sync_channel::>(1); + tx.send(box 1).unwrap(); + } + + #[test] + fn smoke_shared() { + let (tx, rx) = sync_channel::(1); + tx.send(1).unwrap(); + assert_eq!(rx.recv().unwrap(), 1); + let tx = tx.clone(); + tx.send(1).unwrap(); + assert_eq!(rx.recv().unwrap(), 1); + } + + #[test] + fn recv_timeout() { + let (tx, rx) = sync_channel::(1); + assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Err(RecvTimeoutError::Timeout)); + tx.send(1).unwrap(); + assert_eq!(rx.recv_timeout(Duration::from_millis(1)), Ok(1)); + } + + #[test] + fn smoke_threads() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { + tx.send(1).unwrap(); + }); + assert_eq!(rx.recv().unwrap(), 1); + } + + #[test] + fn smoke_port_gone() { + let (tx, rx) = sync_channel::(0); + drop(rx); + assert!(tx.send(1).is_err()); + } + + #[test] + fn smoke_shared_port_gone2() { + let (tx, rx) = sync_channel::(0); + drop(rx); + let tx2 = tx.clone(); + drop(tx); + assert!(tx2.send(1).is_err()); + } + + #[test] + fn port_gone_concurrent() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { + rx.recv().unwrap(); + }); + while tx.send(1).is_ok() {} + } + + #[test] + fn port_gone_concurrent_shared() { + let (tx, rx) = sync_channel::(0); + let tx2 = tx.clone(); + let _t = thread::spawn(move|| { + rx.recv().unwrap(); + }); + while tx.send(1).is_ok() && tx2.send(1).is_ok() {} + } + + #[test] + fn smoke_chan_gone() { + let (tx, rx) = sync_channel::(0); + drop(tx); + assert!(rx.recv().is_err()); + } + + #[test] + fn smoke_chan_gone_shared() { + let (tx, rx) = sync_channel::<()>(0); + let tx2 = tx.clone(); + drop(tx); + drop(tx2); + assert!(rx.recv().is_err()); + } + + #[test] + fn chan_gone_concurrent() { + let (tx, rx) = sync_channel::(0); + thread::spawn(move|| { + tx.send(1).unwrap(); + tx.send(1).unwrap(); + }); + while rx.recv().is_ok() {} + } + + #[test] + fn stress() { + let (tx, rx) = sync_channel::(0); + thread::spawn(move|| { + for _ in 0..10000 { tx.send(1).unwrap(); } + }); + for _ in 0..10000 { + assert_eq!(rx.recv().unwrap(), 1); + } + } + + #[test] + fn stress_recv_timeout_two_threads() { + let (tx, rx) = sync_channel::(0); + + thread::spawn(move|| { + for _ in 0..10000 { tx.send(1).unwrap(); } + }); + + let mut recv_count = 0; + loop { + match rx.recv_timeout(Duration::from_millis(1)) { + Ok(v) => { + assert_eq!(v, 1); + recv_count += 1; + }, + Err(RecvTimeoutError::Timeout) => continue, + Err(RecvTimeoutError::Disconnected) => break, + } + } + + assert_eq!(recv_count, 10000); + } + + #[test] + fn stress_recv_timeout_shared() { + const AMT: u32 = 1000; + const NTHREADS: u32 = 8; + let (tx, rx) = sync_channel::(0); + let (dtx, drx) = sync_channel::<()>(0); + + thread::spawn(move|| { + let mut recv_count = 0; + loop { + match rx.recv_timeout(Duration::from_millis(10)) { + Ok(v) => { + assert_eq!(v, 1); + recv_count += 1; + }, + Err(RecvTimeoutError::Timeout) => continue, + Err(RecvTimeoutError::Disconnected) => break, + } + } + + assert_eq!(recv_count, AMT * NTHREADS); + assert!(rx.try_recv().is_err()); + + dtx.send(()).unwrap(); + }); + + for _ in 0..NTHREADS { + let tx = tx.clone(); + thread::spawn(move|| { + for _ in 0..AMT { tx.send(1).unwrap(); } + }); + } + + drop(tx); + + drx.recv().unwrap(); + } + + #[test] + fn stress_shared() { + const AMT: u32 = 1000; + const NTHREADS: u32 = 8; + let (tx, rx) = sync_channel::(0); + let (dtx, drx) = sync_channel::<()>(0); + + thread::spawn(move|| { + for _ in 0..AMT * NTHREADS { + assert_eq!(rx.recv().unwrap(), 1); + } + match rx.try_recv() { + Ok(..) => panic!(), + _ => {} + } + dtx.send(()).unwrap(); + }); + + for _ in 0..NTHREADS { + let tx = tx.clone(); + thread::spawn(move|| { + for _ in 0..AMT { tx.send(1).unwrap(); } + }); + } + drop(tx); + drx.recv().unwrap(); + } + + #[test] + fn oneshot_single_thread_close_port_first() { + // Simple test of closing without sending + let (_tx, rx) = sync_channel::(0); + drop(rx); + } + + #[test] + fn oneshot_single_thread_close_chan_first() { + // Simple test of closing without sending + let (tx, _rx) = sync_channel::(0); + drop(tx); + } + + #[test] + fn oneshot_single_thread_send_port_close() { + // Testing that the sender cleans up the payload if receiver is closed + let (tx, rx) = sync_channel::>(0); + drop(rx); + assert!(tx.send(box 0).is_err()); + } + + #[test] + fn oneshot_single_thread_recv_chan_close() { + // Receiving on a closed chan will panic + let res = thread::spawn(move|| { + let (tx, rx) = sync_channel::(0); + drop(tx); + rx.recv().unwrap(); + }).join(); + // What is our res? + assert!(res.is_err()); + } + + #[test] + fn oneshot_single_thread_send_then_recv() { + let (tx, rx) = sync_channel::>(1); + tx.send(box 10).unwrap(); + assert!(rx.recv().unwrap() == box 10); + } + + #[test] + fn oneshot_single_thread_try_send_open() { + let (tx, rx) = sync_channel::(1); + assert_eq!(tx.try_send(10), Ok(())); + assert!(rx.recv().unwrap() == 10); + } + + #[test] + fn oneshot_single_thread_try_send_closed() { + let (tx, rx) = sync_channel::(0); + drop(rx); + assert_eq!(tx.try_send(10), Err(TrySendError::Disconnected(10))); + } + + #[test] + fn oneshot_single_thread_try_send_closed2() { + let (tx, _rx) = sync_channel::(0); + assert_eq!(tx.try_send(10), Err(TrySendError::Full(10))); + } + + #[test] + fn oneshot_single_thread_try_recv_open() { + let (tx, rx) = sync_channel::(1); + tx.send(10).unwrap(); + assert!(rx.recv() == Ok(10)); + } + + #[test] + fn oneshot_single_thread_try_recv_closed() { + let (tx, rx) = sync_channel::(0); + drop(tx); + assert!(rx.recv().is_err()); + } + + #[test] + fn oneshot_single_thread_try_recv_closed_with_data() { + let (tx, rx) = sync_channel::(1); + tx.send(10).unwrap(); + drop(tx); + assert_eq!(rx.try_recv(), Ok(10)); + assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected)); + } + + #[test] + fn oneshot_single_thread_peek_data() { + let (tx, rx) = sync_channel::(1); + assert_eq!(rx.try_recv(), Err(TryRecvError::Empty)); + tx.send(10).unwrap(); + assert_eq!(rx.try_recv(), Ok(10)); + } + + #[test] + fn oneshot_single_thread_peek_close() { + let (tx, rx) = sync_channel::(0); + drop(tx); + assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected)); + assert_eq!(rx.try_recv(), Err(TryRecvError::Disconnected)); + } + + #[test] + fn oneshot_single_thread_peek_open() { + let (_tx, rx) = sync_channel::(0); + assert_eq!(rx.try_recv(), Err(TryRecvError::Empty)); + } + + #[test] + fn oneshot_multi_task_recv_then_send() { + let (tx, rx) = sync_channel::>(0); + let _t = thread::spawn(move|| { + assert!(rx.recv().unwrap() == box 10); + }); + + tx.send(box 10).unwrap(); + } + + #[test] + fn oneshot_multi_task_recv_then_close() { + let (tx, rx) = sync_channel::>(0); + let _t = thread::spawn(move|| { + drop(tx); + }); + let res = thread::spawn(move|| { + assert!(rx.recv().unwrap() == box 10); + }).join(); + assert!(res.is_err()); + } + + #[test] + fn oneshot_multi_thread_close_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { + drop(rx); + }); + drop(tx); + } + } + + #[test] + fn oneshot_multi_thread_send_close_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { + drop(rx); + }); + let _ = thread::spawn(move || { + tx.send(1).unwrap(); + }).join(); + } + } + + #[test] + fn oneshot_multi_thread_recv_close_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { + let res = thread::spawn(move|| { + rx.recv().unwrap(); + }).join(); + assert!(res.is_err()); + }); + let _t = thread::spawn(move|| { + thread::spawn(move|| { + drop(tx); + }); + }); + } + } + + #[test] + fn oneshot_multi_thread_send_recv_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = sync_channel::>(0); + let _t = thread::spawn(move|| { + tx.send(box 10).unwrap(); + }); + assert!(rx.recv().unwrap() == box 10); + } + } + + #[test] + fn stream_send_recv_stress() { + for _ in 0..stress_factor() { + let (tx, rx) = sync_channel::>(0); + + send(tx, 0); + recv(rx, 0); + + fn send(tx: SyncSender>, i: i32) { + if i == 10 { return } + + thread::spawn(move|| { + tx.send(box i).unwrap(); + send(tx, i + 1); + }); + } + + fn recv(rx: Receiver>, i: i32) { + if i == 10 { return } + + thread::spawn(move|| { + assert!(rx.recv().unwrap() == box i); + recv(rx, i + 1); + }); + } + } + } + + #[test] + fn recv_a_lot() { + // Regression test that we don't run out of stack in scheduler context + let (tx, rx) = sync_channel(10000); + for _ in 0..10000 { tx.send(()).unwrap(); } + for _ in 0..10000 { rx.recv().unwrap(); } + } + + #[test] + fn shared_chan_stress() { + let (tx, rx) = sync_channel(0); + let total = stress_factor() + 100; + for _ in 0..total { + let tx = tx.clone(); + thread::spawn(move|| { + tx.send(()).unwrap(); + }); + } + + for _ in 0..total { + rx.recv().unwrap(); + } + } + + #[test] + fn test_nested_recv_iter() { + let (tx, rx) = sync_channel::(0); + let (total_tx, total_rx) = sync_channel::(0); + + let _t = thread::spawn(move|| { + let mut acc = 0; + for x in rx.iter() { + acc += x; + } + total_tx.send(acc).unwrap(); + }); + + tx.send(3).unwrap(); + tx.send(1).unwrap(); + tx.send(2).unwrap(); + drop(tx); + assert_eq!(total_rx.recv().unwrap(), 6); + } + + #[test] + fn test_recv_iter_break() { + let (tx, rx) = sync_channel::(0); + let (count_tx, count_rx) = sync_channel(0); + + let _t = thread::spawn(move|| { + let mut count = 0; + for x in rx.iter() { + if count >= 3 { + break; + } else { + count += x; + } + } + count_tx.send(count).unwrap(); + }); + + tx.send(2).unwrap(); + tx.send(2).unwrap(); + tx.send(2).unwrap(); + let _ = tx.try_send(2); + drop(tx); + assert_eq!(count_rx.recv().unwrap(), 4); + } + + #[test] + fn try_recv_states() { + let (tx1, rx1) = sync_channel::(1); + let (tx2, rx2) = sync_channel::<()>(1); + let (tx3, rx3) = sync_channel::<()>(1); + let _t = thread::spawn(move|| { + rx2.recv().unwrap(); + tx1.send(1).unwrap(); + tx3.send(()).unwrap(); + rx2.recv().unwrap(); + drop(tx1); + tx3.send(()).unwrap(); + }); + + assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty)); + tx2.send(()).unwrap(); + rx3.recv().unwrap(); + assert_eq!(rx1.try_recv(), Ok(1)); + assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty)); + tx2.send(()).unwrap(); + rx3.recv().unwrap(); + assert_eq!(rx1.try_recv(), Err(TryRecvError::Disconnected)); + } + + // This bug used to end up in a livelock inside of the Receiver destructor + // because the internal state of the Shared packet was corrupted + #[test] + fn destroy_upgraded_shared_port_when_sender_still_active() { + let (tx, rx) = sync_channel::<()>(0); + let (tx2, rx2) = sync_channel::<()>(0); + let _t = thread::spawn(move|| { + rx.recv().unwrap(); // wait on a oneshot + drop(rx); // destroy a shared + tx2.send(()).unwrap(); + }); + // make sure the other thread has gone to sleep + for _ in 0..5000 { thread::yield_now(); } + + // upgrade to a shared chan and send a message + let t = tx.clone(); + drop(tx); + t.send(()).unwrap(); + + // wait for the child thread to exit before we exit + rx2.recv().unwrap(); + } + + #[test] + fn send1() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { rx.recv().unwrap(); }); + assert_eq!(tx.send(1), Ok(())); + } + + #[test] + fn send2() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { drop(rx); }); + assert!(tx.send(1).is_err()); + } + + #[test] + fn send3() { + let (tx, rx) = sync_channel::(1); + assert_eq!(tx.send(1), Ok(())); + let _t =thread::spawn(move|| { drop(rx); }); + assert!(tx.send(1).is_err()); + } + + #[test] + fn send4() { + let (tx, rx) = sync_channel::(0); + let tx2 = tx.clone(); + let (done, donerx) = channel(); + let done2 = done.clone(); + let _t = thread::spawn(move|| { + assert!(tx.send(1).is_err()); + done.send(()).unwrap(); + }); + let _t = thread::spawn(move|| { + assert!(tx2.send(2).is_err()); + done2.send(()).unwrap(); + }); + drop(rx); + donerx.recv().unwrap(); + donerx.recv().unwrap(); + } + + #[test] + fn try_send1() { + let (tx, _rx) = sync_channel::(0); + assert_eq!(tx.try_send(1), Err(TrySendError::Full(1))); + } + + #[test] + fn try_send2() { + let (tx, _rx) = sync_channel::(1); + assert_eq!(tx.try_send(1), Ok(())); + assert_eq!(tx.try_send(1), Err(TrySendError::Full(1))); + } + + #[test] + fn try_send3() { + let (tx, rx) = sync_channel::(1); + assert_eq!(tx.try_send(1), Ok(())); + drop(rx); + assert_eq!(tx.try_send(1), Err(TrySendError::Disconnected(1))); + } + + #[test] + fn issue_15761() { + fn repro() { + let (tx1, rx1) = sync_channel::<()>(3); + let (tx2, rx2) = sync_channel::<()>(3); + + let _t = thread::spawn(move|| { + rx1.recv().unwrap(); + tx2.try_send(()).unwrap(); + }); + + tx1.try_send(()).unwrap(); + rx2.recv().unwrap(); + } + + for _ in 0..100 { + repro() + } + } + + #[test] + fn fmt_debug_sender() { + let (tx, _) = channel::(); + assert_eq!(format!("{:?}", tx), "Sender { .. }"); + } + + #[test] + fn fmt_debug_recv() { + let (_, rx) = channel::(); + assert_eq!(format!("{:?}", rx), "Receiver { .. }"); + } + + #[test] + fn fmt_debug_sync_sender() { + let (tx, _) = sync_channel::(1); + assert_eq!(format!("{:?}", tx), "SyncSender { .. }"); + } +} diff --git a/ctr-std/src/sync/mpsc/mpsc_queue.rs b/ctr-std/src/sync/mpsc/mpsc_queue.rs new file mode 100644 index 0000000..8d80f94 --- /dev/null +++ b/ctr-std/src/sync/mpsc/mpsc_queue.rs @@ -0,0 +1,198 @@ +/* Copyright (c) 2010-2011 Dmitry Vyukov. All rights reserved. + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY DMITRY VYUKOV "AS IS" AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT + * SHALL DMITRY VYUKOV OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE + * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF + * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * The views and conclusions contained in the software and documentation are + * those of the authors and should not be interpreted as representing official + * policies, either expressed or implied, of Dmitry Vyukov. + */ + +//! A mostly lock-free multi-producer, single consumer queue. +//! +//! This module contains an implementation of a concurrent MPSC queue. This +//! queue can be used to share data between threads, and is also used as the +//! building block of channels in rust. +//! +//! Note that the current implementation of this queue has a caveat of the `pop` +//! method, and see the method for more information about it. Due to this +//! caveat, this queue may not be appropriate for all use-cases. + +// http://www.1024cores.net/home/lock-free-algorithms +// /queues/non-intrusive-mpsc-node-based-queue + +pub use self::PopResult::*; + +use alloc::boxed::Box; +use core::ptr; +use core::cell::UnsafeCell; + +use sync::atomic::{AtomicPtr, Ordering}; + +/// A result of the `pop` function. +pub enum PopResult { + /// Some data has been popped + Data(T), + /// The queue is empty + Empty, + /// The queue is in an inconsistent state. Popping data should succeed, but + /// some pushers have yet to make enough progress in order allow a pop to + /// succeed. It is recommended that a pop() occur "in the near future" in + /// order to see if the sender has made progress or not + Inconsistent, +} + +struct Node { + next: AtomicPtr>, + value: Option, +} + +/// The multi-producer single-consumer structure. This is not cloneable, but it +/// may be safely shared so long as it is guaranteed that there is only one +/// popper at a time (many pushers are allowed). +pub struct Queue { + head: AtomicPtr>, + tail: UnsafeCell<*mut Node>, +} + +unsafe impl Send for Queue { } +unsafe impl Sync for Queue { } + +impl Node { + unsafe fn new(v: Option) -> *mut Node { + Box::into_raw(box Node { + next: AtomicPtr::new(ptr::null_mut()), + value: v, + }) + } +} + +impl Queue { + /// Creates a new queue that is safe to share among multiple producers and + /// one consumer. + pub fn new() -> Queue { + let stub = unsafe { Node::new(None) }; + Queue { + head: AtomicPtr::new(stub), + tail: UnsafeCell::new(stub), + } + } + + /// Pushes a new value onto this queue. + pub fn push(&self, t: T) { + unsafe { + let n = Node::new(Some(t)); + let prev = self.head.swap(n, Ordering::AcqRel); + (*prev).next.store(n, Ordering::Release); + } + } + + /// Pops some data from this queue. + /// + /// Note that the current implementation means that this function cannot + /// return `Option`. It is possible for this queue to be in an + /// inconsistent state where many pushes have succeeded and completely + /// finished, but pops cannot return `Some(t)`. This inconsistent state + /// happens when a pusher is pre-empted at an inopportune moment. + /// + /// This inconsistent state means that this queue does indeed have data, but + /// it does not currently have access to it at this time. + pub fn pop(&self) -> PopResult { + unsafe { + let tail = *self.tail.get(); + let next = (*tail).next.load(Ordering::Acquire); + + if !next.is_null() { + *self.tail.get() = next; + assert!((*tail).value.is_none()); + assert!((*next).value.is_some()); + let ret = (*next).value.take().unwrap(); + let _: Box> = Box::from_raw(tail); + return Data(ret); + } + + if self.head.load(Ordering::Acquire) == tail {Empty} else {Inconsistent} + } + } +} + +impl Drop for Queue { + fn drop(&mut self) { + unsafe { + let mut cur = *self.tail.get(); + while !cur.is_null() { + let next = (*cur).next.load(Ordering::Relaxed); + let _: Box> = Box::from_raw(cur); + cur = next; + } + } + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use sync::mpsc::channel; + use super::{Queue, Data, Empty, Inconsistent}; + use sync::Arc; + use thread; + + #[test] + fn test_full() { + let q: Queue> = Queue::new(); + q.push(box 1); + q.push(box 2); + } + + #[test] + fn test() { + let nthreads = 8; + let nmsgs = 1000; + let q = Queue::new(); + match q.pop() { + Empty => {} + Inconsistent | Data(..) => panic!() + } + let (tx, rx) = channel(); + let q = Arc::new(q); + + for _ in 0..nthreads { + let tx = tx.clone(); + let q = q.clone(); + thread::spawn(move|| { + for i in 0..nmsgs { + q.push(i); + } + tx.send(()).unwrap(); + }); + } + + let mut i = 0; + while i < nthreads * nmsgs { + match q.pop() { + Empty | Inconsistent => {}, + Data(_) => { i += 1 } + } + } + drop(tx); + for _ in 0..nthreads { + rx.recv().unwrap(); + } + } +} diff --git a/ctr-std/src/sync/mpsc/oneshot.rs b/ctr-std/src/sync/mpsc/oneshot.rs new file mode 100644 index 0000000..b8e50c9 --- /dev/null +++ b/ctr-std/src/sync/mpsc/oneshot.rs @@ -0,0 +1,396 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +/// Oneshot channels/ports +/// +/// This is the initial flavor of channels/ports used for comm module. This is +/// an optimization for the one-use case of a channel. The major optimization of +/// this type is to have one and exactly one allocation when the chan/port pair +/// is created. +/// +/// Another possible optimization would be to not use an Arc box because +/// in theory we know when the shared packet can be deallocated (no real need +/// for the atomic reference counting), but I was having trouble how to destroy +/// the data early in a drop of a Port. +/// +/// # Implementation +/// +/// Oneshots are implemented around one atomic usize variable. This variable +/// indicates both the state of the port/chan but also contains any threads +/// blocked on the port. All atomic operations happen on this one word. +/// +/// In order to upgrade a oneshot channel, an upgrade is considered a disconnect +/// on behalf of the channel side of things (it can be mentally thought of as +/// consuming the port). This upgrade is then also stored in the shared packet. +/// The one caveat to consider is that when a port sees a disconnected channel +/// it must check for data because there is no "data plus upgrade" state. + +pub use self::Failure::*; +pub use self::UpgradeResult::*; +pub use self::SelectionResult::*; +use self::MyUpgrade::*; + +use sync::mpsc::Receiver; +use sync::mpsc::blocking::{self, SignalToken}; +use cell::UnsafeCell; +use ptr; +use sync::atomic::{AtomicUsize, Ordering}; +use time::Instant; + +// Various states you can find a port in. +const EMPTY: usize = 0; // initial state: no data, no blocked receiver +const DATA: usize = 1; // data ready for receiver to take +const DISCONNECTED: usize = 2; // channel is disconnected OR upgraded +// Any other value represents a pointer to a SignalToken value. The +// protocol ensures that when the state moves *to* a pointer, +// ownership of the token is given to the packet, and when the state +// moves *from* a pointer, ownership of the token is transferred to +// whoever changed the state. + +pub struct Packet { + // Internal state of the chan/port pair (stores the blocked thread as well) + state: AtomicUsize, + // One-shot data slot location + data: UnsafeCell>, + // when used for the second time, a oneshot channel must be upgraded, and + // this contains the slot for the upgrade + upgrade: UnsafeCell>, +} + +pub enum Failure { + Empty, + Disconnected, + Upgraded(Receiver), +} + +pub enum UpgradeResult { + UpSuccess, + UpDisconnected, + UpWoke(SignalToken), +} + +pub enum SelectionResult { + SelCanceled, + SelUpgraded(SignalToken, Receiver), + SelSuccess, +} + +enum MyUpgrade { + NothingSent, + SendUsed, + GoUp(Receiver), +} + +impl Packet { + pub fn new() -> Packet { + Packet { + data: UnsafeCell::new(None), + upgrade: UnsafeCell::new(NothingSent), + state: AtomicUsize::new(EMPTY), + } + } + + pub fn send(&self, t: T) -> Result<(), T> { + unsafe { + // Sanity check + match *self.upgrade.get() { + NothingSent => {} + _ => panic!("sending on a oneshot that's already sent on "), + } + assert!((*self.data.get()).is_none()); + ptr::write(self.data.get(), Some(t)); + ptr::write(self.upgrade.get(), SendUsed); + + match self.state.swap(DATA, Ordering::SeqCst) { + // Sent the data, no one was waiting + EMPTY => Ok(()), + + // Couldn't send the data, the port hung up first. Return the data + // back up the stack. + DISCONNECTED => { + self.state.swap(DISCONNECTED, Ordering::SeqCst); + ptr::write(self.upgrade.get(), NothingSent); + Err((&mut *self.data.get()).take().unwrap()) + } + + // Not possible, these are one-use channels + DATA => unreachable!(), + + // There is a thread waiting on the other end. We leave the 'DATA' + // state inside so it'll pick it up on the other end. + ptr => { + SignalToken::cast_from_usize(ptr).signal(); + Ok(()) + } + } + } + } + + // Just tests whether this channel has been sent on or not, this is only + // safe to use from the sender. + pub fn sent(&self) -> bool { + unsafe { + match *self.upgrade.get() { + NothingSent => false, + _ => true, + } + } + } + + pub fn recv(&self, deadline: Option) -> Result> { + // Attempt to not block the thread (it's a little expensive). If it looks + // like we're not empty, then immediately go through to `try_recv`. + if self.state.load(Ordering::SeqCst) == EMPTY { + let (wait_token, signal_token) = blocking::tokens(); + let ptr = unsafe { signal_token.cast_to_usize() }; + + // race with senders to enter the blocking state + if self.state.compare_and_swap(EMPTY, ptr, Ordering::SeqCst) == EMPTY { + if let Some(deadline) = deadline { + let timed_out = !wait_token.wait_max_until(deadline); + // Try to reset the state + if timed_out { + self.abort_selection().map_err(Upgraded)?; + } + } else { + wait_token.wait(); + debug_assert!(self.state.load(Ordering::SeqCst) != EMPTY); + } + } else { + // drop the signal token, since we never blocked + drop(unsafe { SignalToken::cast_from_usize(ptr) }); + } + } + + self.try_recv() + } + + pub fn try_recv(&self) -> Result> { + unsafe { + match self.state.load(Ordering::SeqCst) { + EMPTY => Err(Empty), + + // We saw some data on the channel, but the channel can be used + // again to send us an upgrade. As a result, we need to re-insert + // into the channel that there's no data available (otherwise we'll + // just see DATA next time). This is done as a cmpxchg because if + // the state changes under our feet we'd rather just see that state + // change. + DATA => { + self.state.compare_and_swap(DATA, EMPTY, Ordering::SeqCst); + match (&mut *self.data.get()).take() { + Some(data) => Ok(data), + None => unreachable!(), + } + } + + // There's no guarantee that we receive before an upgrade happens, + // and an upgrade flags the channel as disconnected, so when we see + // this we first need to check if there's data available and *then* + // we go through and process the upgrade. + DISCONNECTED => { + match (&mut *self.data.get()).take() { + Some(data) => Ok(data), + None => { + match ptr::replace(self.upgrade.get(), SendUsed) { + SendUsed | NothingSent => Err(Disconnected), + GoUp(upgrade) => Err(Upgraded(upgrade)) + } + } + } + } + + // We are the sole receiver; there cannot be a blocking + // receiver already. + _ => unreachable!() + } + } + } + + // Returns whether the upgrade was completed. If the upgrade wasn't + // completed, then the port couldn't get sent to the other half (it will + // never receive it). + pub fn upgrade(&self, up: Receiver) -> UpgradeResult { + unsafe { + let prev = match *self.upgrade.get() { + NothingSent => NothingSent, + SendUsed => SendUsed, + _ => panic!("upgrading again"), + }; + ptr::write(self.upgrade.get(), GoUp(up)); + + match self.state.swap(DISCONNECTED, Ordering::SeqCst) { + // If the channel is empty or has data on it, then we're good to go. + // Senders will check the data before the upgrade (in case we + // plastered over the DATA state). + DATA | EMPTY => UpSuccess, + + // If the other end is already disconnected, then we failed the + // upgrade. Be sure to trash the port we were given. + DISCONNECTED => { ptr::replace(self.upgrade.get(), prev); UpDisconnected } + + // If someone's waiting, we gotta wake them up + ptr => UpWoke(SignalToken::cast_from_usize(ptr)) + } + } + } + + pub fn drop_chan(&self) { + match self.state.swap(DISCONNECTED, Ordering::SeqCst) { + DATA | DISCONNECTED | EMPTY => {} + + // If someone's waiting, we gotta wake them up + ptr => unsafe { + SignalToken::cast_from_usize(ptr).signal(); + } + } + } + + pub fn drop_port(&self) { + match self.state.swap(DISCONNECTED, Ordering::SeqCst) { + // An empty channel has nothing to do, and a remotely disconnected + // channel also has nothing to do b/c we're about to run the drop + // glue + DISCONNECTED | EMPTY => {} + + // There's data on the channel, so make sure we destroy it promptly. + // This is why not using an arc is a little difficult (need the box + // to stay valid while we take the data). + DATA => unsafe { (&mut *self.data.get()).take().unwrap(); }, + + // We're the only ones that can block on this port + _ => unreachable!() + } + } + + //////////////////////////////////////////////////////////////////////////// + // select implementation + //////////////////////////////////////////////////////////////////////////// + + // If Ok, the value is whether this port has data, if Err, then the upgraded + // port needs to be checked instead of this one. + pub fn can_recv(&self) -> Result> { + unsafe { + match self.state.load(Ordering::SeqCst) { + EMPTY => Ok(false), // Welp, we tried + DATA => Ok(true), // we have some un-acquired data + DISCONNECTED if (*self.data.get()).is_some() => Ok(true), // we have data + DISCONNECTED => { + match ptr::replace(self.upgrade.get(), SendUsed) { + // The other end sent us an upgrade, so we need to + // propagate upwards whether the upgrade can receive + // data + GoUp(upgrade) => Err(upgrade), + + // If the other end disconnected without sending an + // upgrade, then we have data to receive (the channel is + // disconnected). + up => { ptr::write(self.upgrade.get(), up); Ok(true) } + } + } + _ => unreachable!(), // we're the "one blocker" + } + } + } + + // Attempts to start selection on this port. This can either succeed, fail + // because there is data, or fail because there is an upgrade pending. + pub fn start_selection(&self, token: SignalToken) -> SelectionResult { + unsafe { + let ptr = token.cast_to_usize(); + match self.state.compare_and_swap(EMPTY, ptr, Ordering::SeqCst) { + EMPTY => SelSuccess, + DATA => { + drop(SignalToken::cast_from_usize(ptr)); + SelCanceled + } + DISCONNECTED if (*self.data.get()).is_some() => { + drop(SignalToken::cast_from_usize(ptr)); + SelCanceled + } + DISCONNECTED => { + match ptr::replace(self.upgrade.get(), SendUsed) { + // The other end sent us an upgrade, so we need to + // propagate upwards whether the upgrade can receive + // data + GoUp(upgrade) => { + SelUpgraded(SignalToken::cast_from_usize(ptr), upgrade) + } + + // If the other end disconnected without sending an + // upgrade, then we have data to receive (the channel is + // disconnected). + up => { + ptr::write(self.upgrade.get(), up); + drop(SignalToken::cast_from_usize(ptr)); + SelCanceled + } + } + } + _ => unreachable!(), // we're the "one blocker" + } + } + } + + // Remove a previous selecting thread from this port. This ensures that the + // blocked thread will no longer be visible to any other threads. + // + // The return value indicates whether there's data on this port. + pub fn abort_selection(&self) -> Result> { + let state = match self.state.load(Ordering::SeqCst) { + // Each of these states means that no further activity will happen + // with regard to abortion selection + s @ EMPTY | + s @ DATA | + s @ DISCONNECTED => s, + + // If we've got a blocked thread, then use an atomic to gain ownership + // of it (may fail) + ptr => self.state.compare_and_swap(ptr, EMPTY, Ordering::SeqCst) + }; + + // Now that we've got ownership of our state, figure out what to do + // about it. + match state { + EMPTY => unreachable!(), + // our thread used for select was stolen + DATA => Ok(true), + + // If the other end has hung up, then we have complete ownership + // of the port. First, check if there was data waiting for us. This + // is possible if the other end sent something and then hung up. + // + // We then need to check to see if there was an upgrade requested, + // and if so, the upgraded port needs to have its selection aborted. + DISCONNECTED => unsafe { + if (*self.data.get()).is_some() { + Ok(true) + } else { + match ptr::replace(self.upgrade.get(), SendUsed) { + GoUp(port) => Err(port), + _ => Ok(true), + } + } + }, + + // We woke ourselves up from select. + ptr => unsafe { + drop(SignalToken::cast_from_usize(ptr)); + Ok(false) + } + } + } +} + +impl Drop for Packet { + fn drop(&mut self) { + assert_eq!(self.state.load(Ordering::SeqCst), DISCONNECTED); + } +} diff --git a/ctr-std/src/sync/mpsc/select.rs b/ctr-std/src/sync/mpsc/select.rs new file mode 100644 index 0000000..8b4da53 --- /dev/null +++ b/ctr-std/src/sync/mpsc/select.rs @@ -0,0 +1,791 @@ +// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! Selection over an array of receivers +//! +//! This module contains the implementation machinery necessary for selecting +//! over a number of receivers. One large goal of this module is to provide an +//! efficient interface to selecting over any receiver of any type. +//! +//! This is achieved through an architecture of a "receiver set" in which +//! receivers are added to a set and then the entire set is waited on at once. +//! The set can be waited on multiple times to prevent re-adding each receiver +//! to the set. +//! +//! Usage of this module is currently encouraged to go through the use of the +//! `select!` macro. This macro allows naturally binding of variables to the +//! received values of receivers in a much more natural syntax then usage of the +//! `Select` structure directly. +//! +//! # Examples +//! +//! ```rust +//! #![feature(mpsc_select)] +//! +//! use std::sync::mpsc::channel; +//! +//! let (tx1, rx1) = channel(); +//! let (tx2, rx2) = channel(); +//! +//! tx1.send(1).unwrap(); +//! tx2.send(2).unwrap(); +//! +//! select! { +//! val = rx1.recv() => { +//! assert_eq!(val.unwrap(), 1); +//! }, +//! val = rx2.recv() => { +//! assert_eq!(val.unwrap(), 2); +//! } +//! } +//! ``` + +#![allow(dead_code)] +#![unstable(feature = "mpsc_select", + reason = "This implementation, while likely sufficient, is unsafe and \ + likely to be error prone. At some point in the future this \ + module will likely be replaced, and it is currently \ + unknown how much API breakage that will cause. The ability \ + to select over a number of channels will remain forever, \ + but no guarantees beyond this are being made", + issue = "27800")] + + +use fmt; + +use core::cell::{Cell, UnsafeCell}; +use core::marker; +use core::ptr; +use core::usize; + +use sync::mpsc::{Receiver, RecvError}; +use sync::mpsc::blocking::{self, SignalToken}; + +/// The "receiver set" of the select interface. This structure is used to manage +/// a set of receivers which are being selected over. +pub struct Select { + inner: UnsafeCell, + next_id: Cell, +} + +struct SelectInner { + head: *mut Handle<'static, ()>, + tail: *mut Handle<'static, ()>, +} + +impl !marker::Send for Select {} + +/// A handle to a receiver which is currently a member of a `Select` set of +/// receivers. This handle is used to keep the receiver in the set as well as +/// interact with the underlying receiver. +pub struct Handle<'rx, T:Send+'rx> { + /// The ID of this handle, used to compare against the return value of + /// `Select::wait()` + id: usize, + selector: *mut SelectInner, + next: *mut Handle<'static, ()>, + prev: *mut Handle<'static, ()>, + added: bool, + packet: &'rx (Packet+'rx), + + // due to our fun transmutes, we be sure to place this at the end. (nothing + // previous relies on T) + rx: &'rx Receiver, +} + +struct Packets { cur: *mut Handle<'static, ()> } + +#[doc(hidden)] +#[derive(PartialEq, Eq)] +pub enum StartResult { + Installed, + Abort, +} + +#[doc(hidden)] +pub trait Packet { + fn can_recv(&self) -> bool; + fn start_selection(&self, token: SignalToken) -> StartResult; + fn abort_selection(&self) -> bool; +} + +impl Select { + /// Creates a new selection structure. This set is initially empty. + /// + /// Usage of this struct directly can sometimes be burdensome, and usage is much easier through + /// the `select!` macro. + /// + /// # Examples + /// + /// ``` + /// #![feature(mpsc_select)] + /// + /// use std::sync::mpsc::Select; + /// + /// let select = Select::new(); + /// ``` + pub fn new() -> Select { + Select { + inner: UnsafeCell::new(SelectInner { + head: ptr::null_mut(), + tail: ptr::null_mut(), + }), + next_id: Cell::new(1), + } + } + + /// Creates a new handle into this receiver set for a new receiver. Note + /// that this does *not* add the receiver to the receiver set, for that you + /// must call the `add` method on the handle itself. + pub fn handle<'a, T: Send>(&'a self, rx: &'a Receiver) -> Handle<'a, T> { + let id = self.next_id.get(); + self.next_id.set(id + 1); + Handle { + id: id, + selector: self.inner.get(), + next: ptr::null_mut(), + prev: ptr::null_mut(), + added: false, + rx: rx, + packet: rx, + } + } + + /// Waits for an event on this receiver set. The returned value is *not* an + /// index, but rather an id. This id can be queried against any active + /// `Handle` structures (each one has an `id` method). The handle with + /// the matching `id` will have some sort of event available on it. The + /// event could either be that data is available or the corresponding + /// channel has been closed. + pub fn wait(&self) -> usize { + self.wait2(true) + } + + /// Helper method for skipping the preflight checks during testing + fn wait2(&self, do_preflight_checks: bool) -> usize { + // Note that this is currently an inefficient implementation. We in + // theory have knowledge about all receivers in the set ahead of time, + // so this method shouldn't really have to iterate over all of them yet + // again. The idea with this "receiver set" interface is to get the + // interface right this time around, and later this implementation can + // be optimized. + // + // This implementation can be summarized by: + // + // fn select(receivers) { + // if any receiver ready { return ready index } + // deschedule { + // block on all receivers + // } + // unblock on all receivers + // return ready index + // } + // + // Most notably, the iterations over all of the receivers shouldn't be + // necessary. + unsafe { + // Stage 1: preflight checks. Look for any packets ready to receive + if do_preflight_checks { + for handle in self.iter() { + if (*handle).packet.can_recv() { + return (*handle).id(); + } + } + } + + // Stage 2: begin the blocking process + // + // Create a number of signal tokens, and install each one + // sequentially until one fails. If one fails, then abort the + // selection on the already-installed tokens. + let (wait_token, signal_token) = blocking::tokens(); + for (i, handle) in self.iter().enumerate() { + match (*handle).packet.start_selection(signal_token.clone()) { + StartResult::Installed => {} + StartResult::Abort => { + // Go back and abort the already-begun selections + for handle in self.iter().take(i) { + (*handle).packet.abort_selection(); + } + return (*handle).id; + } + } + } + + // Stage 3: no messages available, actually block + wait_token.wait(); + + // Stage 4: there *must* be message available; find it. + // + // Abort the selection process on each receiver. If the abort + // process returns `true`, then that means that the receiver is + // ready to receive some data. Note that this also means that the + // receiver may have yet to have fully read the `to_wake` field and + // woken us up (although the wakeup is guaranteed to fail). + // + // This situation happens in the window of where a sender invokes + // increment(), sees -1, and then decides to wake up the thread. After + // all this is done, the sending thread will set `selecting` to + // `false`. Until this is done, we cannot return. If we were to + // return, then a sender could wake up a receiver which has gone + // back to sleep after this call to `select`. + // + // Note that it is a "fairly small window" in which an increment() + // views that it should wake a thread up until the `selecting` bit + // is set to false. For now, the implementation currently just spins + // in a yield loop. This is very distasteful, but this + // implementation is already nowhere near what it should ideally be. + // A rewrite should focus on avoiding a yield loop, and for now this + // implementation is tying us over to a more efficient "don't + // iterate over everything every time" implementation. + let mut ready_id = usize::MAX; + for handle in self.iter() { + if (*handle).packet.abort_selection() { + ready_id = (*handle).id; + } + } + + // We must have found a ready receiver + assert!(ready_id != usize::MAX); + return ready_id; + } + } + + fn iter(&self) -> Packets { Packets { cur: unsafe { &*self.inner.get() }.head } } +} + +impl<'rx, T: Send> Handle<'rx, T> { + /// Retrieves the id of this handle. + #[inline] + pub fn id(&self) -> usize { self.id } + + /// Blocks to receive a value on the underlying receiver, returning `Some` on + /// success or `None` if the channel disconnects. This function has the same + /// semantics as `Receiver.recv` + pub fn recv(&mut self) -> Result { self.rx.recv() } + + /// Adds this handle to the receiver set that the handle was created from. This + /// method can be called multiple times, but it has no effect if `add` was + /// called previously. + /// + /// This method is unsafe because it requires that the `Handle` is not moved + /// while it is added to the `Select` set. + pub unsafe fn add(&mut self) { + if self.added { return } + let selector = &mut *self.selector; + let me = self as *mut Handle<'rx, T> as *mut Handle<'static, ()>; + + if selector.head.is_null() { + selector.head = me; + selector.tail = me; + } else { + (*me).prev = selector.tail; + assert!((*me).next.is_null()); + (*selector.tail).next = me; + selector.tail = me; + } + self.added = true; + } + + /// Removes this handle from the `Select` set. This method is unsafe because + /// it has no guarantee that the `Handle` was not moved since `add` was + /// called. + pub unsafe fn remove(&mut self) { + if !self.added { return } + + let selector = &mut *self.selector; + let me = self as *mut Handle<'rx, T> as *mut Handle<'static, ()>; + + if self.prev.is_null() { + assert_eq!(selector.head, me); + selector.head = self.next; + } else { + (*self.prev).next = self.next; + } + if self.next.is_null() { + assert_eq!(selector.tail, me); + selector.tail = self.prev; + } else { + (*self.next).prev = self.prev; + } + + self.next = ptr::null_mut(); + self.prev = ptr::null_mut(); + + self.added = false; + } +} + +impl Drop for Select { + fn drop(&mut self) { + unsafe { + assert!((&*self.inner.get()).head.is_null()); + assert!((&*self.inner.get()).tail.is_null()); + } + } +} + +impl<'rx, T: Send> Drop for Handle<'rx, T> { + fn drop(&mut self) { + unsafe { self.remove() } + } +} + +impl Iterator for Packets { + type Item = *mut Handle<'static, ()>; + + fn next(&mut self) -> Option<*mut Handle<'static, ()>> { + if self.cur.is_null() { + None + } else { + let ret = Some(self.cur); + unsafe { self.cur = (*self.cur).next; } + ret + } + } +} + +impl fmt::Debug for Select { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!(f, "Select {{ .. }}") + } +} + +impl<'rx, T:Send+'rx> fmt::Debug for Handle<'rx, T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!(f, "Handle {{ .. }}") + } +} + +#[allow(unused_imports)] +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use thread; + use sync::mpsc::*; + + // Don't use the libstd version so we can pull in the right Select structure + // (std::comm points at the wrong one) + macro_rules! select { + ( + $($name:pat = $rx:ident.$meth:ident() => $code:expr),+ + ) => ({ + let sel = Select::new(); + $( let mut $rx = sel.handle(&$rx); )+ + unsafe { + $( $rx.add(); )+ + } + let ret = sel.wait(); + $( if ret == $rx.id() { let $name = $rx.$meth(); $code } else )+ + { unreachable!() } + }) + } + + #[test] + fn smoke() { + let (tx1, rx1) = channel::(); + let (tx2, rx2) = channel::(); + tx1.send(1).unwrap(); + select! { + foo = rx1.recv() => { assert_eq!(foo.unwrap(), 1); }, + _bar = rx2.recv() => { panic!() } + } + tx2.send(2).unwrap(); + select! { + _foo = rx1.recv() => { panic!() }, + bar = rx2.recv() => { assert_eq!(bar.unwrap(), 2) } + } + drop(tx1); + select! { + foo = rx1.recv() => { assert!(foo.is_err()); }, + _bar = rx2.recv() => { panic!() } + } + drop(tx2); + select! { + bar = rx2.recv() => { assert!(bar.is_err()); } + } + } + + #[test] + fn smoke2() { + let (_tx1, rx1) = channel::(); + let (_tx2, rx2) = channel::(); + let (_tx3, rx3) = channel::(); + let (_tx4, rx4) = channel::(); + let (tx5, rx5) = channel::(); + tx5.send(4).unwrap(); + select! { + _foo = rx1.recv() => { panic!("1") }, + _foo = rx2.recv() => { panic!("2") }, + _foo = rx3.recv() => { panic!("3") }, + _foo = rx4.recv() => { panic!("4") }, + foo = rx5.recv() => { assert_eq!(foo.unwrap(), 4); } + } + } + + #[test] + fn closed() { + let (_tx1, rx1) = channel::(); + let (tx2, rx2) = channel::(); + drop(tx2); + + select! { + _a1 = rx1.recv() => { panic!() }, + a2 = rx2.recv() => { assert!(a2.is_err()); } + } + } + + #[test] + fn unblocks() { + let (tx1, rx1) = channel::(); + let (_tx2, rx2) = channel::(); + let (tx3, rx3) = channel::(); + + let _t = thread::spawn(move|| { + for _ in 0..20 { thread::yield_now(); } + tx1.send(1).unwrap(); + rx3.recv().unwrap(); + for _ in 0..20 { thread::yield_now(); } + }); + + select! { + a = rx1.recv() => { assert_eq!(a.unwrap(), 1); }, + _b = rx2.recv() => { panic!() } + } + tx3.send(1).unwrap(); + select! { + a = rx1.recv() => { assert!(a.is_err()) }, + _b = rx2.recv() => { panic!() } + } + } + + #[test] + fn both_ready() { + let (tx1, rx1) = channel::(); + let (tx2, rx2) = channel::(); + let (tx3, rx3) = channel::<()>(); + + let _t = thread::spawn(move|| { + for _ in 0..20 { thread::yield_now(); } + tx1.send(1).unwrap(); + tx2.send(2).unwrap(); + rx3.recv().unwrap(); + }); + + select! { + a = rx1.recv() => { assert_eq!(a.unwrap(), 1); }, + a = rx2.recv() => { assert_eq!(a.unwrap(), 2); } + } + select! { + a = rx1.recv() => { assert_eq!(a.unwrap(), 1); }, + a = rx2.recv() => { assert_eq!(a.unwrap(), 2); } + } + assert_eq!(rx1.try_recv(), Err(TryRecvError::Empty)); + assert_eq!(rx2.try_recv(), Err(TryRecvError::Empty)); + tx3.send(()).unwrap(); + } + + #[test] + fn stress() { + const AMT: i32 = 10000; + let (tx1, rx1) = channel::(); + let (tx2, rx2) = channel::(); + let (tx3, rx3) = channel::<()>(); + + let _t = thread::spawn(move|| { + for i in 0..AMT { + if i % 2 == 0 { + tx1.send(i).unwrap(); + } else { + tx2.send(i).unwrap(); + } + rx3.recv().unwrap(); + } + }); + + for i in 0..AMT { + select! { + i1 = rx1.recv() => { assert!(i % 2 == 0 && i == i1.unwrap()); }, + i2 = rx2.recv() => { assert!(i % 2 == 1 && i == i2.unwrap()); } + } + tx3.send(()).unwrap(); + } + } + + #[test] + fn cloning() { + let (tx1, rx1) = channel::(); + let (_tx2, rx2) = channel::(); + let (tx3, rx3) = channel::<()>(); + + let _t = thread::spawn(move|| { + rx3.recv().unwrap(); + tx1.clone(); + assert_eq!(rx3.try_recv(), Err(TryRecvError::Empty)); + tx1.send(2).unwrap(); + rx3.recv().unwrap(); + }); + + tx3.send(()).unwrap(); + select! { + _i1 = rx1.recv() => {}, + _i2 = rx2.recv() => panic!() + } + tx3.send(()).unwrap(); + } + + #[test] + fn cloning2() { + let (tx1, rx1) = channel::(); + let (_tx2, rx2) = channel::(); + let (tx3, rx3) = channel::<()>(); + + let _t = thread::spawn(move|| { + rx3.recv().unwrap(); + tx1.clone(); + assert_eq!(rx3.try_recv(), Err(TryRecvError::Empty)); + tx1.send(2).unwrap(); + rx3.recv().unwrap(); + }); + + tx3.send(()).unwrap(); + select! { + _i1 = rx1.recv() => {}, + _i2 = rx2.recv() => panic!() + } + tx3.send(()).unwrap(); + } + + #[test] + fn cloning3() { + let (tx1, rx1) = channel::<()>(); + let (tx2, rx2) = channel::<()>(); + let (tx3, rx3) = channel::<()>(); + let _t = thread::spawn(move|| { + let s = Select::new(); + let mut h1 = s.handle(&rx1); + let mut h2 = s.handle(&rx2); + unsafe { h2.add(); } + unsafe { h1.add(); } + assert_eq!(s.wait(), h2.id); + tx3.send(()).unwrap(); + }); + + for _ in 0..1000 { thread::yield_now(); } + drop(tx1.clone()); + tx2.send(()).unwrap(); + rx3.recv().unwrap(); + } + + #[test] + fn preflight1() { + let (tx, rx) = channel(); + tx.send(()).unwrap(); + select! { + _n = rx.recv() => {} + } + } + + #[test] + fn preflight2() { + let (tx, rx) = channel(); + tx.send(()).unwrap(); + tx.send(()).unwrap(); + select! { + _n = rx.recv() => {} + } + } + + #[test] + fn preflight3() { + let (tx, rx) = channel(); + drop(tx.clone()); + tx.send(()).unwrap(); + select! { + _n = rx.recv() => {} + } + } + + #[test] + fn preflight4() { + let (tx, rx) = channel(); + tx.send(()).unwrap(); + let s = Select::new(); + let mut h = s.handle(&rx); + unsafe { h.add(); } + assert_eq!(s.wait2(false), h.id); + } + + #[test] + fn preflight5() { + let (tx, rx) = channel(); + tx.send(()).unwrap(); + tx.send(()).unwrap(); + let s = Select::new(); + let mut h = s.handle(&rx); + unsafe { h.add(); } + assert_eq!(s.wait2(false), h.id); + } + + #[test] + fn preflight6() { + let (tx, rx) = channel(); + drop(tx.clone()); + tx.send(()).unwrap(); + let s = Select::new(); + let mut h = s.handle(&rx); + unsafe { h.add(); } + assert_eq!(s.wait2(false), h.id); + } + + #[test] + fn preflight7() { + let (tx, rx) = channel::<()>(); + drop(tx); + let s = Select::new(); + let mut h = s.handle(&rx); + unsafe { h.add(); } + assert_eq!(s.wait2(false), h.id); + } + + #[test] + fn preflight8() { + let (tx, rx) = channel(); + tx.send(()).unwrap(); + drop(tx); + rx.recv().unwrap(); + let s = Select::new(); + let mut h = s.handle(&rx); + unsafe { h.add(); } + assert_eq!(s.wait2(false), h.id); + } + + #[test] + fn preflight9() { + let (tx, rx) = channel(); + drop(tx.clone()); + tx.send(()).unwrap(); + drop(tx); + rx.recv().unwrap(); + let s = Select::new(); + let mut h = s.handle(&rx); + unsafe { h.add(); } + assert_eq!(s.wait2(false), h.id); + } + + #[test] + fn oneshot_data_waiting() { + let (tx1, rx1) = channel(); + let (tx2, rx2) = channel(); + let _t = thread::spawn(move|| { + select! { + _n = rx1.recv() => {} + } + tx2.send(()).unwrap(); + }); + + for _ in 0..100 { thread::yield_now() } + tx1.send(()).unwrap(); + rx2.recv().unwrap(); + } + + #[test] + fn stream_data_waiting() { + let (tx1, rx1) = channel(); + let (tx2, rx2) = channel(); + tx1.send(()).unwrap(); + tx1.send(()).unwrap(); + rx1.recv().unwrap(); + rx1.recv().unwrap(); + let _t = thread::spawn(move|| { + select! { + _n = rx1.recv() => {} + } + tx2.send(()).unwrap(); + }); + + for _ in 0..100 { thread::yield_now() } + tx1.send(()).unwrap(); + rx2.recv().unwrap(); + } + + #[test] + fn shared_data_waiting() { + let (tx1, rx1) = channel(); + let (tx2, rx2) = channel(); + drop(tx1.clone()); + tx1.send(()).unwrap(); + rx1.recv().unwrap(); + let _t = thread::spawn(move|| { + select! { + _n = rx1.recv() => {} + } + tx2.send(()).unwrap(); + }); + + for _ in 0..100 { thread::yield_now() } + tx1.send(()).unwrap(); + rx2.recv().unwrap(); + } + + #[test] + fn sync1() { + let (tx, rx) = sync_channel::(1); + tx.send(1).unwrap(); + select! { + n = rx.recv() => { assert_eq!(n.unwrap(), 1); } + } + } + + #[test] + fn sync2() { + let (tx, rx) = sync_channel::(0); + let _t = thread::spawn(move|| { + for _ in 0..100 { thread::yield_now() } + tx.send(1).unwrap(); + }); + select! { + n = rx.recv() => { assert_eq!(n.unwrap(), 1); } + } + } + + #[test] + fn sync3() { + let (tx1, rx1) = sync_channel::(0); + let (tx2, rx2): (Sender, Receiver) = channel(); + let _t = thread::spawn(move|| { tx1.send(1).unwrap(); }); + let _t = thread::spawn(move|| { tx2.send(2).unwrap(); }); + select! { + n = rx1.recv() => { + let n = n.unwrap(); + assert_eq!(n, 1); + assert_eq!(rx2.recv().unwrap(), 2); + }, + n = rx2.recv() => { + let n = n.unwrap(); + assert_eq!(n, 2); + assert_eq!(rx1.recv().unwrap(), 1); + } + } + } + + #[test] + fn fmt_debug_select() { + let sel = Select::new(); + assert_eq!(format!("{:?}", sel), "Select { .. }"); + } + + #[test] + fn fmt_debug_handle() { + let (_, rx) = channel::(); + let sel = Select::new(); + let handle = sel.handle(&rx); + assert_eq!(format!("{:?}", handle), "Handle { .. }"); + } +} diff --git a/ctr-std/src/sync/mpsc/shared.rs b/ctr-std/src/sync/mpsc/shared.rs new file mode 100644 index 0000000..f9e0290 --- /dev/null +++ b/ctr-std/src/sync/mpsc/shared.rs @@ -0,0 +1,506 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +/// Shared channels +/// +/// This is the flavor of channels which are not necessarily optimized for any +/// particular use case, but are the most general in how they are used. Shared +/// channels are cloneable allowing for multiple senders. +/// +/// High level implementation details can be found in the comment of the parent +/// module. You'll also note that the implementation of the shared and stream +/// channels are quite similar, and this is no coincidence! + +pub use self::Failure::*; + +use core::cmp; +use core::intrinsics::abort; +use core::isize; + +use cell::UnsafeCell; +use ptr; +use sync::atomic::{AtomicUsize, AtomicIsize, AtomicBool, Ordering}; +use sync::mpsc::blocking::{self, SignalToken}; +use sync::mpsc::mpsc_queue as mpsc; +use sync::mpsc::select::StartResult::*; +use sync::mpsc::select::StartResult; +use sync::{Mutex, MutexGuard}; +use thread; +use time::Instant; + +const DISCONNECTED: isize = isize::MIN; +const FUDGE: isize = 1024; +const MAX_REFCOUNT: usize = (isize::MAX) as usize; +#[cfg(test)] +const MAX_STEALS: isize = 5; +#[cfg(not(test))] +const MAX_STEALS: isize = 1 << 20; + +pub struct Packet { + queue: mpsc::Queue, + cnt: AtomicIsize, // How many items are on this channel + steals: UnsafeCell, // How many times has a port received without blocking? + to_wake: AtomicUsize, // SignalToken for wake up + + // The number of channels which are currently using this packet. + channels: AtomicUsize, + + // See the discussion in Port::drop and the channel send methods for what + // these are used for + port_dropped: AtomicBool, + sender_drain: AtomicIsize, + + // this lock protects various portions of this implementation during + // select() + select_lock: Mutex<()>, +} + +pub enum Failure { + Empty, + Disconnected, +} + +impl Packet { + // Creation of a packet *must* be followed by a call to postinit_lock + // and later by inherit_blocker + pub fn new() -> Packet { + Packet { + queue: mpsc::Queue::new(), + cnt: AtomicIsize::new(0), + steals: UnsafeCell::new(0), + to_wake: AtomicUsize::new(0), + channels: AtomicUsize::new(2), + port_dropped: AtomicBool::new(false), + sender_drain: AtomicIsize::new(0), + select_lock: Mutex::new(()), + } + } + + // This function should be used after newly created Packet + // was wrapped with an Arc + // In other case mutex data will be duplicated while cloning + // and that could cause problems on platforms where it is + // represented by opaque data structure + pub fn postinit_lock(&self) -> MutexGuard<()> { + self.select_lock.lock().unwrap() + } + + // This function is used at the creation of a shared packet to inherit a + // previously blocked thread. This is done to prevent spurious wakeups of + // threads in select(). + // + // This can only be called at channel-creation time + pub fn inherit_blocker(&self, + token: Option, + guard: MutexGuard<()>) { + token.map(|token| { + assert_eq!(self.cnt.load(Ordering::SeqCst), 0); + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + self.to_wake.store(unsafe { token.cast_to_usize() }, Ordering::SeqCst); + self.cnt.store(-1, Ordering::SeqCst); + + // This store is a little sketchy. What's happening here is that + // we're transferring a blocker from a oneshot or stream channel to + // this shared channel. In doing so, we never spuriously wake them + // up and rather only wake them up at the appropriate time. This + // implementation of shared channels assumes that any blocking + // recv() will undo the increment of steals performed in try_recv() + // once the recv is complete. This thread that we're inheriting, + // however, is not in the middle of recv. Hence, the first time we + // wake them up, they're going to wake up from their old port, move + // on to the upgraded port, and then call the block recv() function. + // + // When calling this function, they'll find there's data immediately + // available, counting it as a steal. This in fact wasn't a steal + // because we appropriately blocked them waiting for data. + // + // To offset this bad increment, we initially set the steal count to + // -1. You'll find some special code in abort_selection() as well to + // ensure that this -1 steal count doesn't escape too far. + unsafe { *self.steals.get() = -1; } + }); + + // When the shared packet is constructed, we grabbed this lock. The + // purpose of this lock is to ensure that abort_selection() doesn't + // interfere with this method. After we unlock this lock, we're + // signifying that we're done modifying self.cnt and self.to_wake and + // the port is ready for the world to continue using it. + drop(guard); + } + + pub fn send(&self, t: T) -> Result<(), T> { + // See Port::drop for what's going on + if self.port_dropped.load(Ordering::SeqCst) { return Err(t) } + + // Note that the multiple sender case is a little trickier + // semantically than the single sender case. The logic for + // incrementing is "add and if disconnected store disconnected". + // This could end up leading some senders to believe that there + // wasn't a disconnect if in fact there was a disconnect. This means + // that while one thread is attempting to re-store the disconnected + // states, other threads could walk through merrily incrementing + // this very-negative disconnected count. To prevent senders from + // spuriously attempting to send when the channels is actually + // disconnected, the count has a ranged check here. + // + // This is also done for another reason. Remember that the return + // value of this function is: + // + // `true` == the data *may* be received, this essentially has no + // meaning + // `false` == the data will *never* be received, this has a lot of + // meaning + // + // In the SPSC case, we have a check of 'queue.is_empty()' to see + // whether the data was actually received, but this same condition + // means nothing in a multi-producer context. As a result, this + // preflight check serves as the definitive "this will never be + // received". Once we get beyond this check, we have permanently + // entered the realm of "this may be received" + if self.cnt.load(Ordering::SeqCst) < DISCONNECTED + FUDGE { + return Err(t) + } + + self.queue.push(t); + match self.cnt.fetch_add(1, Ordering::SeqCst) { + -1 => { + self.take_to_wake().signal(); + } + + // In this case, we have possibly failed to send our data, and + // we need to consider re-popping the data in order to fully + // destroy it. We must arbitrate among the multiple senders, + // however, because the queues that we're using are + // single-consumer queues. In order to do this, all exiting + // pushers will use an atomic count in order to count those + // flowing through. Pushers who see 0 are required to drain as + // much as possible, and then can only exit when they are the + // only pusher (otherwise they must try again). + n if n < DISCONNECTED + FUDGE => { + // see the comment in 'try' for a shared channel for why this + // window of "not disconnected" is ok. + self.cnt.store(DISCONNECTED, Ordering::SeqCst); + + if self.sender_drain.fetch_add(1, Ordering::SeqCst) == 0 { + loop { + // drain the queue, for info on the thread yield see the + // discussion in try_recv + loop { + match self.queue.pop() { + mpsc::Data(..) => {} + mpsc::Empty => break, + mpsc::Inconsistent => thread::yield_now(), + } + } + // maybe we're done, if we're not the last ones + // here, then we need to go try again. + if self.sender_drain.fetch_sub(1, Ordering::SeqCst) == 1 { + break + } + } + + // At this point, there may still be data on the queue, + // but only if the count hasn't been incremented and + // some other sender hasn't finished pushing data just + // yet. That sender in question will drain its own data. + } + } + + // Can't make any assumptions about this case like in the SPSC case. + _ => {} + } + + Ok(()) + } + + pub fn recv(&self, deadline: Option) -> Result { + // This code is essentially the exact same as that found in the stream + // case (see stream.rs) + match self.try_recv() { + Err(Empty) => {} + data => return data, + } + + let (wait_token, signal_token) = blocking::tokens(); + if self.decrement(signal_token) == Installed { + if let Some(deadline) = deadline { + let timed_out = !wait_token.wait_max_until(deadline); + if timed_out { + self.abort_selection(false); + } + } else { + wait_token.wait(); + } + } + + match self.try_recv() { + data @ Ok(..) => unsafe { *self.steals.get() -= 1; data }, + data => data, + } + } + + // Essentially the exact same thing as the stream decrement function. + // Returns true if blocking should proceed. + fn decrement(&self, token: SignalToken) -> StartResult { + unsafe { + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + let ptr = token.cast_to_usize(); + self.to_wake.store(ptr, Ordering::SeqCst); + + let steals = ptr::replace(self.steals.get(), 0); + + match self.cnt.fetch_sub(1 + steals, Ordering::SeqCst) { + DISCONNECTED => { self.cnt.store(DISCONNECTED, Ordering::SeqCst); } + // If we factor in our steals and notice that the channel has no + // data, we successfully sleep + n => { + assert!(n >= 0); + if n - steals <= 0 { return Installed } + } + } + + self.to_wake.store(0, Ordering::SeqCst); + drop(SignalToken::cast_from_usize(ptr)); + Abort + } + } + + pub fn try_recv(&self) -> Result { + let ret = match self.queue.pop() { + mpsc::Data(t) => Some(t), + mpsc::Empty => None, + + // This is a bit of an interesting case. The channel is reported as + // having data available, but our pop() has failed due to the queue + // being in an inconsistent state. This means that there is some + // pusher somewhere which has yet to complete, but we are guaranteed + // that a pop will eventually succeed. In this case, we spin in a + // yield loop because the remote sender should finish their enqueue + // operation "very quickly". + // + // Avoiding this yield loop would require a different queue + // abstraction which provides the guarantee that after M pushes have + // succeeded, at least M pops will succeed. The current queues + // guarantee that if there are N active pushes, you can pop N times + // once all N have finished. + mpsc::Inconsistent => { + let data; + loop { + thread::yield_now(); + match self.queue.pop() { + mpsc::Data(t) => { data = t; break } + mpsc::Empty => panic!("inconsistent => empty"), + mpsc::Inconsistent => {} + } + } + Some(data) + } + }; + match ret { + // See the discussion in the stream implementation for why we + // might decrement steals. + Some(data) => unsafe { + if *self.steals.get() > MAX_STEALS { + match self.cnt.swap(0, Ordering::SeqCst) { + DISCONNECTED => { + self.cnt.store(DISCONNECTED, Ordering::SeqCst); + } + n => { + let m = cmp::min(n, *self.steals.get()); + *self.steals.get() -= m; + self.bump(n - m); + } + } + assert!(*self.steals.get() >= 0); + } + *self.steals.get() += 1; + Ok(data) + }, + + // See the discussion in the stream implementation for why we try + // again. + None => { + match self.cnt.load(Ordering::SeqCst) { + n if n != DISCONNECTED => Err(Empty), + _ => { + match self.queue.pop() { + mpsc::Data(t) => Ok(t), + mpsc::Empty => Err(Disconnected), + // with no senders, an inconsistency is impossible. + mpsc::Inconsistent => unreachable!(), + } + } + } + } + } + } + + // Prepares this shared packet for a channel clone, essentially just bumping + // a refcount. + pub fn clone_chan(&self) { + let old_count = self.channels.fetch_add(1, Ordering::SeqCst); + + // See comments on Arc::clone() on why we do this (for `mem::forget`). + if old_count > MAX_REFCOUNT { + unsafe { + abort(); + } + } + } + + // Decrement the reference count on a channel. This is called whenever a + // Chan is dropped and may end up waking up a receiver. It's the receiver's + // responsibility on the other end to figure out that we've disconnected. + pub fn drop_chan(&self) { + match self.channels.fetch_sub(1, Ordering::SeqCst) { + 1 => {} + n if n > 1 => return, + n => panic!("bad number of channels left {}", n), + } + + match self.cnt.swap(DISCONNECTED, Ordering::SeqCst) { + -1 => { self.take_to_wake().signal(); } + DISCONNECTED => {} + n => { assert!(n >= 0); } + } + } + + // See the long discussion inside of stream.rs for why the queue is drained, + // and why it is done in this fashion. + pub fn drop_port(&self) { + self.port_dropped.store(true, Ordering::SeqCst); + let mut steals = unsafe { *self.steals.get() }; + while { + let cnt = self.cnt.compare_and_swap(steals, DISCONNECTED, Ordering::SeqCst); + cnt != DISCONNECTED && cnt != steals + } { + // See the discussion in 'try_recv' for why we yield + // control of this thread. + loop { + match self.queue.pop() { + mpsc::Data(..) => { steals += 1; } + mpsc::Empty | mpsc::Inconsistent => break, + } + } + } + } + + // Consumes ownership of the 'to_wake' field. + fn take_to_wake(&self) -> SignalToken { + let ptr = self.to_wake.load(Ordering::SeqCst); + self.to_wake.store(0, Ordering::SeqCst); + assert!(ptr != 0); + unsafe { SignalToken::cast_from_usize(ptr) } + } + + //////////////////////////////////////////////////////////////////////////// + // select implementation + //////////////////////////////////////////////////////////////////////////// + + // Helper function for select, tests whether this port can receive without + // blocking (obviously not an atomic decision). + // + // This is different than the stream version because there's no need to peek + // at the queue, we can just look at the local count. + pub fn can_recv(&self) -> bool { + let cnt = self.cnt.load(Ordering::SeqCst); + cnt == DISCONNECTED || cnt - unsafe { *self.steals.get() } > 0 + } + + // increment the count on the channel (used for selection) + fn bump(&self, amt: isize) -> isize { + match self.cnt.fetch_add(amt, Ordering::SeqCst) { + DISCONNECTED => { + self.cnt.store(DISCONNECTED, Ordering::SeqCst); + DISCONNECTED + } + n => n + } + } + + // Inserts the signal token for selection on this port, returning true if + // blocking should proceed. + // + // The code here is the same as in stream.rs, except that it doesn't need to + // peek at the channel to see if an upgrade is pending. + pub fn start_selection(&self, token: SignalToken) -> StartResult { + match self.decrement(token) { + Installed => Installed, + Abort => { + let prev = self.bump(1); + assert!(prev == DISCONNECTED || prev >= 0); + Abort + } + } + } + + // Cancels a previous thread waiting on this port, returning whether there's + // data on the port. + // + // This is similar to the stream implementation (hence fewer comments), but + // uses a different value for the "steals" variable. + pub fn abort_selection(&self, _was_upgrade: bool) -> bool { + // Before we do anything else, we bounce on this lock. The reason for + // doing this is to ensure that any upgrade-in-progress is gone and + // done with. Without this bounce, we can race with inherit_blocker + // about looking at and dealing with to_wake. Once we have acquired the + // lock, we are guaranteed that inherit_blocker is done. + { + let _guard = self.select_lock.lock().unwrap(); + } + + // Like the stream implementation, we want to make sure that the count + // on the channel goes non-negative. We don't know how negative the + // stream currently is, so instead of using a steal value of 1, we load + // the channel count and figure out what we should do to make it + // positive. + let steals = { + let cnt = self.cnt.load(Ordering::SeqCst); + if cnt < 0 && cnt != DISCONNECTED {-cnt} else {0} + }; + let prev = self.bump(steals + 1); + + if prev == DISCONNECTED { + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + true + } else { + let cur = prev + steals + 1; + assert!(cur >= 0); + if prev < 0 { + drop(self.take_to_wake()); + } else { + while self.to_wake.load(Ordering::SeqCst) != 0 { + thread::yield_now(); + } + } + unsafe { + // if the number of steals is -1, it was the pre-emptive -1 steal + // count from when we inherited a blocker. This is fine because + // we're just going to overwrite it with a real value. + let old = self.steals.get(); + assert!(*old == 0 || *old == -1); + *old = steals; + prev >= 0 + } + } + } +} + +impl Drop for Packet { + fn drop(&mut self) { + // Note that this load is not only an assert for correctness about + // disconnection, but also a proper fence before the read of + // `to_wake`, so this assert cannot be removed with also removing + // the `to_wake` assert. + assert_eq!(self.cnt.load(Ordering::SeqCst), DISCONNECTED); + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + assert_eq!(self.channels.load(Ordering::SeqCst), 0); + } +} diff --git a/ctr-std/src/sync/mpsc/spsc_queue.rs b/ctr-std/src/sync/mpsc/spsc_queue.rs new file mode 100644 index 0000000..5858e4b --- /dev/null +++ b/ctr-std/src/sync/mpsc/spsc_queue.rs @@ -0,0 +1,337 @@ +/* Copyright (c) 2010-2011 Dmitry Vyukov. All rights reserved. + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY DMITRY VYUKOV "AS IS" AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT + * SHALL DMITRY VYUKOV OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE + * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF + * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * The views and conclusions contained in the software and documentation are + * those of the authors and should not be interpreted as representing official + * policies, either expressed or implied, of Dmitry Vyukov. + */ + +// http://www.1024cores.net/home/lock-free-algorithms/queues/unbounded-spsc-queue + +//! A single-producer single-consumer concurrent queue +//! +//! This module contains the implementation of an SPSC queue which can be used +//! concurrently between two threads. This data structure is safe to use and +//! enforces the semantics that there is one pusher and one popper. + +use alloc::boxed::Box; +use core::ptr; +use core::cell::UnsafeCell; + +use sync::atomic::{AtomicPtr, AtomicUsize, Ordering}; + +// Node within the linked list queue of messages to send +struct Node { + // FIXME: this could be an uninitialized T if we're careful enough, and + // that would reduce memory usage (and be a bit faster). + // is it worth it? + value: Option, // nullable for re-use of nodes + next: AtomicPtr>, // next node in the queue +} + +/// The single-producer single-consumer queue. This structure is not cloneable, +/// but it can be safely shared in an Arc if it is guaranteed that there +/// is only one popper and one pusher touching the queue at any one point in +/// time. +pub struct Queue { + // consumer fields + tail: UnsafeCell<*mut Node>, // where to pop from + tail_prev: AtomicPtr>, // where to pop from + + // producer fields + head: UnsafeCell<*mut Node>, // where to push to + first: UnsafeCell<*mut Node>, // where to get new nodes from + tail_copy: UnsafeCell<*mut Node>, // between first/tail + + // Cache maintenance fields. Additions and subtractions are stored + // separately in order to allow them to use nonatomic addition/subtraction. + cache_bound: usize, + cache_additions: AtomicUsize, + cache_subtractions: AtomicUsize, +} + +unsafe impl Send for Queue { } + +unsafe impl Sync for Queue { } + +impl Node { + fn new() -> *mut Node { + Box::into_raw(box Node { + value: None, + next: AtomicPtr::new(ptr::null_mut::>()), + }) + } +} + +impl Queue { + /// Creates a new queue. + /// + /// This is unsafe as the type system doesn't enforce a single + /// consumer-producer relationship. It also allows the consumer to `pop` + /// items while there is a `peek` active due to all methods having a + /// non-mutable receiver. + /// + /// # Arguments + /// + /// * `bound` - This queue implementation is implemented with a linked + /// list, and this means that a push is always a malloc. In + /// order to amortize this cost, an internal cache of nodes is + /// maintained to prevent a malloc from always being + /// necessary. This bound is the limit on the size of the + /// cache (if desired). If the value is 0, then the cache has + /// no bound. Otherwise, the cache will never grow larger than + /// `bound` (although the queue itself could be much larger. + pub unsafe fn new(bound: usize) -> Queue { + let n1 = Node::new(); + let n2 = Node::new(); + (*n1).next.store(n2, Ordering::Relaxed); + Queue { + tail: UnsafeCell::new(n2), + tail_prev: AtomicPtr::new(n1), + head: UnsafeCell::new(n2), + first: UnsafeCell::new(n1), + tail_copy: UnsafeCell::new(n1), + cache_bound: bound, + cache_additions: AtomicUsize::new(0), + cache_subtractions: AtomicUsize::new(0), + } + } + + /// Pushes a new value onto this queue. Note that to use this function + /// safely, it must be externally guaranteed that there is only one pusher. + pub fn push(&self, t: T) { + unsafe { + // Acquire a node (which either uses a cached one or allocates a new + // one), and then append this to the 'head' node. + let n = self.alloc(); + assert!((*n).value.is_none()); + (*n).value = Some(t); + (*n).next.store(ptr::null_mut(), Ordering::Relaxed); + (**self.head.get()).next.store(n, Ordering::Release); + *self.head.get() = n; + } + } + + unsafe fn alloc(&self) -> *mut Node { + // First try to see if we can consume the 'first' node for our uses. + // We try to avoid as many atomic instructions as possible here, so + // the addition to cache_subtractions is not atomic (plus we're the + // only one subtracting from the cache). + if *self.first.get() != *self.tail_copy.get() { + if self.cache_bound > 0 { + let b = self.cache_subtractions.load(Ordering::Relaxed); + self.cache_subtractions.store(b + 1, Ordering::Relaxed); + } + let ret = *self.first.get(); + *self.first.get() = (*ret).next.load(Ordering::Relaxed); + return ret; + } + // If the above fails, then update our copy of the tail and try + // again. + *self.tail_copy.get() = self.tail_prev.load(Ordering::Acquire); + if *self.first.get() != *self.tail_copy.get() { + if self.cache_bound > 0 { + let b = self.cache_subtractions.load(Ordering::Relaxed); + self.cache_subtractions.store(b + 1, Ordering::Relaxed); + } + let ret = *self.first.get(); + *self.first.get() = (*ret).next.load(Ordering::Relaxed); + return ret; + } + // If all of that fails, then we have to allocate a new node + // (there's nothing in the node cache). + Node::new() + } + + /// Attempts to pop a value from this queue. Remember that to use this type + /// safely you must ensure that there is only one popper at a time. + pub fn pop(&self) -> Option { + unsafe { + // The `tail` node is not actually a used node, but rather a + // sentinel from where we should start popping from. Hence, look at + // tail's next field and see if we can use it. If we do a pop, then + // the current tail node is a candidate for going into the cache. + let tail = *self.tail.get(); + let next = (*tail).next.load(Ordering::Acquire); + if next.is_null() { return None } + assert!((*next).value.is_some()); + let ret = (*next).value.take(); + + *self.tail.get() = next; + if self.cache_bound == 0 { + self.tail_prev.store(tail, Ordering::Release); + } else { + // FIXME: this is dubious with overflow. + let additions = self.cache_additions.load(Ordering::Relaxed); + let subtractions = self.cache_subtractions.load(Ordering::Relaxed); + let size = additions - subtractions; + + if size < self.cache_bound { + self.tail_prev.store(tail, Ordering::Release); + self.cache_additions.store(additions + 1, Ordering::Relaxed); + } else { + (*self.tail_prev.load(Ordering::Relaxed)) + .next.store(next, Ordering::Relaxed); + // We have successfully erased all references to 'tail', so + // now we can safely drop it. + let _: Box> = Box::from_raw(tail); + } + } + ret + } + } + + /// Attempts to peek at the head of the queue, returning `None` if the queue + /// has no data currently + /// + /// # Warning + /// The reference returned is invalid if it is not used before the consumer + /// pops the value off the queue. If the producer then pushes another value + /// onto the queue, it will overwrite the value pointed to by the reference. + pub fn peek(&self) -> Option<&mut T> { + // This is essentially the same as above with all the popping bits + // stripped out. + unsafe { + let tail = *self.tail.get(); + let next = (*tail).next.load(Ordering::Acquire); + if next.is_null() { None } else { (*next).value.as_mut() } + } + } +} + +impl Drop for Queue { + fn drop(&mut self) { + unsafe { + let mut cur = *self.first.get(); + while !cur.is_null() { + let next = (*cur).next.load(Ordering::Relaxed); + let _n: Box> = Box::from_raw(cur); + cur = next; + } + } + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use sync::Arc; + use super::Queue; + use thread; + use sync::mpsc::channel; + + #[test] + fn smoke() { + unsafe { + let queue = Queue::new(0); + queue.push(1); + queue.push(2); + assert_eq!(queue.pop(), Some(1)); + assert_eq!(queue.pop(), Some(2)); + assert_eq!(queue.pop(), None); + queue.push(3); + queue.push(4); + assert_eq!(queue.pop(), Some(3)); + assert_eq!(queue.pop(), Some(4)); + assert_eq!(queue.pop(), None); + } + } + + #[test] + fn peek() { + unsafe { + let queue = Queue::new(0); + queue.push(vec![1]); + + // Ensure the borrowchecker works + match queue.peek() { + Some(vec) => { + assert_eq!(&*vec, &[1]); + }, + None => unreachable!() + } + + match queue.pop() { + Some(vec) => { + assert_eq!(&*vec, &[1]); + }, + None => unreachable!() + } + } + } + + #[test] + fn drop_full() { + unsafe { + let q: Queue> = Queue::new(0); + q.push(box 1); + q.push(box 2); + } + } + + #[test] + fn smoke_bound() { + unsafe { + let q = Queue::new(0); + q.push(1); + q.push(2); + assert_eq!(q.pop(), Some(1)); + assert_eq!(q.pop(), Some(2)); + assert_eq!(q.pop(), None); + q.push(3); + q.push(4); + assert_eq!(q.pop(), Some(3)); + assert_eq!(q.pop(), Some(4)); + assert_eq!(q.pop(), None); + } + } + + #[test] + fn stress() { + unsafe { + stress_bound(0); + stress_bound(1); + } + + unsafe fn stress_bound(bound: usize) { + let q = Arc::new(Queue::new(bound)); + + let (tx, rx) = channel(); + let q2 = q.clone(); + let _t = thread::spawn(move|| { + for _ in 0..100000 { + loop { + match q2.pop() { + Some(1) => break, + Some(_) => panic!(), + None => {} + } + } + } + tx.send(()).unwrap(); + }); + for _ in 0..100000 { + q.push(1); + } + rx.recv().unwrap(); + } + } +} diff --git a/ctr-std/src/sync/mpsc/stream.rs b/ctr-std/src/sync/mpsc/stream.rs new file mode 100644 index 0000000..47cd897 --- /dev/null +++ b/ctr-std/src/sync/mpsc/stream.rs @@ -0,0 +1,487 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +/// Stream channels +/// +/// This is the flavor of channels which are optimized for one sender and one +/// receiver. The sender will be upgraded to a shared channel if the channel is +/// cloned. +/// +/// High level implementation details can be found in the comment of the parent +/// module. + +pub use self::Failure::*; +pub use self::UpgradeResult::*; +pub use self::SelectionResult::*; +use self::Message::*; + +use cell::UnsafeCell; +use core::cmp; +use core::isize; +use ptr; +use thread; +use time::Instant; + +use sync::atomic::{AtomicIsize, AtomicUsize, Ordering, AtomicBool}; +use sync::mpsc::Receiver; +use sync::mpsc::blocking::{self, SignalToken}; +use sync::mpsc::spsc_queue as spsc; + +const DISCONNECTED: isize = isize::MIN; +#[cfg(test)] +const MAX_STEALS: isize = 5; +#[cfg(not(test))] +const MAX_STEALS: isize = 1 << 20; + +pub struct Packet { + queue: spsc::Queue>, // internal queue for all message + + cnt: AtomicIsize, // How many items are on this channel + steals: UnsafeCell, // How many times has a port received without blocking? + to_wake: AtomicUsize, // SignalToken for the blocked thread to wake up + + port_dropped: AtomicBool, // flag if the channel has been destroyed. +} + +pub enum Failure { + Empty, + Disconnected, + Upgraded(Receiver), +} + +pub enum UpgradeResult { + UpSuccess, + UpDisconnected, + UpWoke(SignalToken), +} + +pub enum SelectionResult { + SelSuccess, + SelCanceled, + SelUpgraded(SignalToken, Receiver), +} + +// Any message could contain an "upgrade request" to a new shared port, so the +// internal queue it's a queue of T, but rather Message +enum Message { + Data(T), + GoUp(Receiver), +} + +impl Packet { + pub fn new() -> Packet { + Packet { + queue: unsafe { spsc::Queue::new(128) }, + + cnt: AtomicIsize::new(0), + steals: UnsafeCell::new(0), + to_wake: AtomicUsize::new(0), + + port_dropped: AtomicBool::new(false), + } + } + + pub fn send(&self, t: T) -> Result<(), T> { + // If the other port has deterministically gone away, then definitely + // must return the data back up the stack. Otherwise, the data is + // considered as being sent. + if self.port_dropped.load(Ordering::SeqCst) { return Err(t) } + + match self.do_send(Data(t)) { + UpSuccess | UpDisconnected => {}, + UpWoke(token) => { token.signal(); } + } + Ok(()) + } + + pub fn upgrade(&self, up: Receiver) -> UpgradeResult { + // If the port has gone away, then there's no need to proceed any + // further. + if self.port_dropped.load(Ordering::SeqCst) { return UpDisconnected } + + self.do_send(GoUp(up)) + } + + fn do_send(&self, t: Message) -> UpgradeResult { + self.queue.push(t); + match self.cnt.fetch_add(1, Ordering::SeqCst) { + // As described in the mod's doc comment, -1 == wakeup + -1 => UpWoke(self.take_to_wake()), + // As as described before, SPSC queues must be >= -2 + -2 => UpSuccess, + + // Be sure to preserve the disconnected state, and the return value + // in this case is going to be whether our data was received or not. + // This manifests itself on whether we have an empty queue or not. + // + // Primarily, are required to drain the queue here because the port + // will never remove this data. We can only have at most one item to + // drain (the port drains the rest). + DISCONNECTED => { + self.cnt.store(DISCONNECTED, Ordering::SeqCst); + let first = self.queue.pop(); + let second = self.queue.pop(); + assert!(second.is_none()); + + match first { + Some(..) => UpSuccess, // we failed to send the data + None => UpDisconnected, // we successfully sent data + } + } + + // Otherwise we just sent some data on a non-waiting queue, so just + // make sure the world is sane and carry on! + n => { assert!(n >= 0); UpSuccess } + } + } + + // Consumes ownership of the 'to_wake' field. + fn take_to_wake(&self) -> SignalToken { + let ptr = self.to_wake.load(Ordering::SeqCst); + self.to_wake.store(0, Ordering::SeqCst); + assert!(ptr != 0); + unsafe { SignalToken::cast_from_usize(ptr) } + } + + // Decrements the count on the channel for a sleeper, returning the sleeper + // back if it shouldn't sleep. Note that this is the location where we take + // steals into account. + fn decrement(&self, token: SignalToken) -> Result<(), SignalToken> { + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + let ptr = unsafe { token.cast_to_usize() }; + self.to_wake.store(ptr, Ordering::SeqCst); + + let steals = unsafe { ptr::replace(self.steals.get(), 0) }; + + match self.cnt.fetch_sub(1 + steals, Ordering::SeqCst) { + DISCONNECTED => { self.cnt.store(DISCONNECTED, Ordering::SeqCst); } + // If we factor in our steals and notice that the channel has no + // data, we successfully sleep + n => { + assert!(n >= 0); + if n - steals <= 0 { return Ok(()) } + } + } + + self.to_wake.store(0, Ordering::SeqCst); + Err(unsafe { SignalToken::cast_from_usize(ptr) }) + } + + pub fn recv(&self, deadline: Option) -> Result> { + // Optimistic preflight check (scheduling is expensive). + match self.try_recv() { + Err(Empty) => {} + data => return data, + } + + // Welp, our channel has no data. Deschedule the current thread and + // initiate the blocking protocol. + let (wait_token, signal_token) = blocking::tokens(); + if self.decrement(signal_token).is_ok() { + if let Some(deadline) = deadline { + let timed_out = !wait_token.wait_max_until(deadline); + if timed_out { + self.abort_selection(/* was_upgrade = */ false).map_err(Upgraded)?; + } + } else { + wait_token.wait(); + } + } + + match self.try_recv() { + // Messages which actually popped from the queue shouldn't count as + // a steal, so offset the decrement here (we already have our + // "steal" factored into the channel count above). + data @ Ok(..) | + data @ Err(Upgraded(..)) => unsafe { + *self.steals.get() -= 1; + data + }, + + data => data, + } + } + + pub fn try_recv(&self) -> Result> { + match self.queue.pop() { + // If we stole some data, record to that effect (this will be + // factored into cnt later on). + // + // Note that we don't allow steals to grow without bound in order to + // prevent eventual overflow of either steals or cnt as an overflow + // would have catastrophic results. Sometimes, steals > cnt, but + // other times cnt > steals, so we don't know the relation between + // steals and cnt. This code path is executed only rarely, so we do + // a pretty slow operation, of swapping 0 into cnt, taking steals + // down as much as possible (without going negative), and then + // adding back in whatever we couldn't factor into steals. + Some(data) => unsafe { + if *self.steals.get() > MAX_STEALS { + match self.cnt.swap(0, Ordering::SeqCst) { + DISCONNECTED => { + self.cnt.store(DISCONNECTED, Ordering::SeqCst); + } + n => { + let m = cmp::min(n, *self.steals.get()); + *self.steals.get() -= m; + self.bump(n - m); + } + } + assert!(*self.steals.get() >= 0); + } + *self.steals.get() += 1; + match data { + Data(t) => Ok(t), + GoUp(up) => Err(Upgraded(up)), + } + }, + + None => { + match self.cnt.load(Ordering::SeqCst) { + n if n != DISCONNECTED => Err(Empty), + + // This is a little bit of a tricky case. We failed to pop + // data above, and then we have viewed that the channel is + // disconnected. In this window more data could have been + // sent on the channel. It doesn't really make sense to + // return that the channel is disconnected when there's + // actually data on it, so be extra sure there's no data by + // popping one more time. + // + // We can ignore steals because the other end is + // disconnected and we'll never need to really factor in our + // steals again. + _ => { + match self.queue.pop() { + Some(Data(t)) => Ok(t), + Some(GoUp(up)) => Err(Upgraded(up)), + None => Err(Disconnected), + } + } + } + } + } + } + + pub fn drop_chan(&self) { + // Dropping a channel is pretty simple, we just flag it as disconnected + // and then wakeup a blocker if there is one. + match self.cnt.swap(DISCONNECTED, Ordering::SeqCst) { + -1 => { self.take_to_wake().signal(); } + DISCONNECTED => {} + n => { assert!(n >= 0); } + } + } + + pub fn drop_port(&self) { + // Dropping a port seems like a fairly trivial thing. In theory all we + // need to do is flag that we're disconnected and then everything else + // can take over (we don't have anyone to wake up). + // + // The catch for Ports is that we want to drop the entire contents of + // the queue. There are multiple reasons for having this property, the + // largest of which is that if another chan is waiting in this channel + // (but not received yet), then waiting on that port will cause a + // deadlock. + // + // So if we accept that we must now destroy the entire contents of the + // queue, this code may make a bit more sense. The tricky part is that + // we can't let any in-flight sends go un-dropped, we have to make sure + // *everything* is dropped and nothing new will come onto the channel. + + // The first thing we do is set a flag saying that we're done for. All + // sends are gated on this flag, so we're immediately guaranteed that + // there are a bounded number of active sends that we'll have to deal + // with. + self.port_dropped.store(true, Ordering::SeqCst); + + // Now that we're guaranteed to deal with a bounded number of senders, + // we need to drain the queue. This draining process happens atomically + // with respect to the "count" of the channel. If the count is nonzero + // (with steals taken into account), then there must be data on the + // channel. In this case we drain everything and then try again. We will + // continue to fail while active senders send data while we're dropping + // data, but eventually we're guaranteed to break out of this loop + // (because there is a bounded number of senders). + let mut steals = unsafe { *self.steals.get() }; + while { + let cnt = self.cnt.compare_and_swap( + steals, DISCONNECTED, Ordering::SeqCst); + cnt != DISCONNECTED && cnt != steals + } { + while let Some(_) = self.queue.pop() { steals += 1; } + } + + // At this point in time, we have gated all future senders from sending, + // and we have flagged the channel as being disconnected. The senders + // still have some responsibility, however, because some sends may not + // complete until after we flag the disconnection. There are more + // details in the sending methods that see DISCONNECTED + } + + //////////////////////////////////////////////////////////////////////////// + // select implementation + //////////////////////////////////////////////////////////////////////////// + + // Tests to see whether this port can receive without blocking. If Ok is + // returned, then that's the answer. If Err is returned, then the returned + // port needs to be queried instead (an upgrade happened) + pub fn can_recv(&self) -> Result> { + // We peek at the queue to see if there's anything on it, and we use + // this return value to determine if we should pop from the queue and + // upgrade this channel immediately. If it looks like we've got an + // upgrade pending, then go through the whole recv rigamarole to update + // the internal state. + match self.queue.peek() { + Some(&mut GoUp(..)) => { + match self.recv(None) { + Err(Upgraded(port)) => Err(port), + _ => unreachable!(), + } + } + Some(..) => Ok(true), + None => Ok(false) + } + } + + // increment the count on the channel (used for selection) + fn bump(&self, amt: isize) -> isize { + match self.cnt.fetch_add(amt, Ordering::SeqCst) { + DISCONNECTED => { + self.cnt.store(DISCONNECTED, Ordering::SeqCst); + DISCONNECTED + } + n => n + } + } + + // Attempts to start selecting on this port. Like a oneshot, this can fail + // immediately because of an upgrade. + pub fn start_selection(&self, token: SignalToken) -> SelectionResult { + match self.decrement(token) { + Ok(()) => SelSuccess, + Err(token) => { + let ret = match self.queue.peek() { + Some(&mut GoUp(..)) => { + match self.queue.pop() { + Some(GoUp(port)) => SelUpgraded(token, port), + _ => unreachable!(), + } + } + Some(..) => SelCanceled, + None => SelCanceled, + }; + // Undo our decrement above, and we should be guaranteed that the + // previous value is positive because we're not going to sleep + let prev = self.bump(1); + assert!(prev == DISCONNECTED || prev >= 0); + ret + } + } + } + + // Removes a previous thread from being blocked in this port + pub fn abort_selection(&self, + was_upgrade: bool) -> Result> { + // If we're aborting selection after upgrading from a oneshot, then + // we're guarantee that no one is waiting. The only way that we could + // have seen the upgrade is if data was actually sent on the channel + // half again. For us, this means that there is guaranteed to be data on + // this channel. Furthermore, we're guaranteed that there was no + // start_selection previously, so there's no need to modify `self.cnt` + // at all. + // + // Hence, because of these invariants, we immediately return `Ok(true)`. + // Note that the data may not actually be sent on the channel just yet. + // The other end could have flagged the upgrade but not sent data to + // this end. This is fine because we know it's a small bounded windows + // of time until the data is actually sent. + if was_upgrade { + assert_eq!(unsafe { *self.steals.get() }, 0); + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + return Ok(true) + } + + // We want to make sure that the count on the channel goes non-negative, + // and in the stream case we can have at most one steal, so just assume + // that we had one steal. + let steals = 1; + let prev = self.bump(steals + 1); + + // If we were previously disconnected, then we know for sure that there + // is no thread in to_wake, so just keep going + let has_data = if prev == DISCONNECTED { + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + true // there is data, that data is that we're disconnected + } else { + let cur = prev + steals + 1; + assert!(cur >= 0); + + // If the previous count was negative, then we just made things go + // positive, hence we passed the -1 boundary and we're responsible + // for removing the to_wake() field and trashing it. + // + // If the previous count was positive then we're in a tougher + // situation. A possible race is that a sender just incremented + // through -1 (meaning it's going to try to wake a thread up), but it + // hasn't yet read the to_wake. In order to prevent a future recv() + // from waking up too early (this sender picking up the plastered + // over to_wake), we spin loop here waiting for to_wake to be 0. + // Note that this entire select() implementation needs an overhaul, + // and this is *not* the worst part of it, so this is not done as a + // final solution but rather out of necessity for now to get + // something working. + if prev < 0 { + drop(self.take_to_wake()); + } else { + while self.to_wake.load(Ordering::SeqCst) != 0 { + thread::yield_now(); + } + } + unsafe { + assert_eq!(*self.steals.get(), 0); + *self.steals.get() = steals; + } + + // if we were previously positive, then there's surely data to + // receive + prev >= 0 + }; + + // Now that we've determined that this queue "has data", we peek at the + // queue to see if the data is an upgrade or not. If it's an upgrade, + // then we need to destroy this port and abort selection on the + // upgraded port. + if has_data { + match self.queue.peek() { + Some(&mut GoUp(..)) => { + match self.queue.pop() { + Some(GoUp(port)) => Err(port), + _ => unreachable!(), + } + } + _ => Ok(true), + } + } else { + Ok(false) + } + } +} + +impl Drop for Packet { + fn drop(&mut self) { + // Note that this load is not only an assert for correctness about + // disconnection, but also a proper fence before the read of + // `to_wake`, so this assert cannot be removed with also removing + // the `to_wake` assert. + assert_eq!(self.cnt.load(Ordering::SeqCst), DISCONNECTED); + assert_eq!(self.to_wake.load(Ordering::SeqCst), 0); + } +} diff --git a/ctr-std/src/sync/mpsc/sync.rs b/ctr-std/src/sync/mpsc/sync.rs new file mode 100644 index 0000000..1d16e00 --- /dev/null +++ b/ctr-std/src/sync/mpsc/sync.rs @@ -0,0 +1,528 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +/// Synchronous channels/ports +/// +/// This channel implementation differs significantly from the asynchronous +/// implementations found next to it (oneshot/stream/share). This is an +/// implementation of a synchronous, bounded buffer channel. +/// +/// Each channel is created with some amount of backing buffer, and sends will +/// *block* until buffer space becomes available. A buffer size of 0 is valid, +/// which means that every successful send is paired with a successful recv. +/// +/// This flavor of channels defines a new `send_opt` method for channels which +/// is the method by which a message is sent but the thread does not panic if it +/// cannot be delivered. +/// +/// Another major difference is that send() will *always* return back the data +/// if it couldn't be sent. This is because it is deterministically known when +/// the data is received and when it is not received. +/// +/// Implementation-wise, it can all be summed up with "use a mutex plus some +/// logic". The mutex used here is an OS native mutex, meaning that no user code +/// is run inside of the mutex (to prevent context switching). This +/// implementation shares almost all code for the buffered and unbuffered cases +/// of a synchronous channel. There are a few branches for the unbuffered case, +/// but they're mostly just relevant to blocking senders. + +pub use self::Failure::*; +use self::Blocker::*; + +use core::intrinsics::abort; +use core::isize; +use core::mem; +use core::ptr; + +use sync::atomic::{Ordering, AtomicUsize}; +use sync::mpsc::blocking::{self, WaitToken, SignalToken}; +use sync::mpsc::select::StartResult::{self, Installed, Abort}; +use sync::{Mutex, MutexGuard}; +use time::Instant; + +const MAX_REFCOUNT: usize = (isize::MAX) as usize; + +pub struct Packet { + /// Only field outside of the mutex. Just done for kicks, but mainly because + /// the other shared channel already had the code implemented + channels: AtomicUsize, + + lock: Mutex>, +} + +unsafe impl Send for Packet { } + +unsafe impl Sync for Packet { } + +struct State { + disconnected: bool, // Is the channel disconnected yet? + queue: Queue, // queue of senders waiting to send data + blocker: Blocker, // currently blocked thread on this channel + buf: Buffer, // storage for buffered messages + cap: usize, // capacity of this channel + + /// A curious flag used to indicate whether a sender failed or succeeded in + /// blocking. This is used to transmit information back to the thread that it + /// must dequeue its message from the buffer because it was not received. + /// This is only relevant in the 0-buffer case. This obviously cannot be + /// safely constructed, but it's guaranteed to always have a valid pointer + /// value. + canceled: Option<&'static mut bool>, +} + +unsafe impl Send for State {} + +/// Possible flavors of threads who can be blocked on this channel. +enum Blocker { + BlockedSender(SignalToken), + BlockedReceiver(SignalToken), + NoneBlocked +} + +/// Simple queue for threading threads together. Nodes are stack-allocated, so +/// this structure is not safe at all +struct Queue { + head: *mut Node, + tail: *mut Node, +} + +struct Node { + token: Option, + next: *mut Node, +} + +unsafe impl Send for Node {} + +/// A simple ring-buffer +struct Buffer { + buf: Vec>, + start: usize, + size: usize, +} + +#[derive(Debug)] +pub enum Failure { + Empty, + Disconnected, +} + +/// Atomically blocks the current thread, placing it into `slot`, unlocking `lock` +/// in the meantime. This re-locks the mutex upon returning. +fn wait<'a, 'b, T>(lock: &'a Mutex>, + mut guard: MutexGuard<'b, State>, + f: fn(SignalToken) -> Blocker) + -> MutexGuard<'a, State> +{ + let (wait_token, signal_token) = blocking::tokens(); + match mem::replace(&mut guard.blocker, f(signal_token)) { + NoneBlocked => {} + _ => unreachable!(), + } + drop(guard); // unlock + wait_token.wait(); // block + lock.lock().unwrap() // relock +} + +/// Same as wait, but waiting at most until `deadline`. +fn wait_timeout_receiver<'a, 'b, T>(lock: &'a Mutex>, + deadline: Instant, + mut guard: MutexGuard<'b, State>, + success: &mut bool) + -> MutexGuard<'a, State> +{ + let (wait_token, signal_token) = blocking::tokens(); + match mem::replace(&mut guard.blocker, BlockedReceiver(signal_token)) { + NoneBlocked => {} + _ => unreachable!(), + } + drop(guard); // unlock + *success = wait_token.wait_max_until(deadline); // block + let mut new_guard = lock.lock().unwrap(); // relock + if !*success { + abort_selection(&mut new_guard); + } + new_guard +} + +fn abort_selection<'a, T>(guard: &mut MutexGuard<'a , State>) -> bool { + match mem::replace(&mut guard.blocker, NoneBlocked) { + NoneBlocked => true, + BlockedSender(token) => { + guard.blocker = BlockedSender(token); + true + } + BlockedReceiver(token) => { drop(token); false } + } +} + +/// Wakes up a thread, dropping the lock at the correct time +fn wakeup(token: SignalToken, guard: MutexGuard>) { + // We need to be careful to wake up the waiting thread *outside* of the mutex + // in case it incurs a context switch. + drop(guard); + token.signal(); +} + +impl Packet { + pub fn new(cap: usize) -> Packet { + Packet { + channels: AtomicUsize::new(1), + lock: Mutex::new(State { + disconnected: false, + blocker: NoneBlocked, + cap: cap, + canceled: None, + queue: Queue { + head: ptr::null_mut(), + tail: ptr::null_mut(), + }, + buf: Buffer { + buf: (0..cap + if cap == 0 {1} else {0}).map(|_| None).collect(), + start: 0, + size: 0, + }, + }), + } + } + + // wait until a send slot is available, returning locked access to + // the channel state. + fn acquire_send_slot(&self) -> MutexGuard> { + let mut node = Node { token: None, next: ptr::null_mut() }; + loop { + let mut guard = self.lock.lock().unwrap(); + // are we ready to go? + if guard.disconnected || guard.buf.size() < guard.buf.cap() { + return guard; + } + // no room; actually block + let wait_token = guard.queue.enqueue(&mut node); + drop(guard); + wait_token.wait(); + } + } + + pub fn send(&self, t: T) -> Result<(), T> { + let mut guard = self.acquire_send_slot(); + if guard.disconnected { return Err(t) } + guard.buf.enqueue(t); + + match mem::replace(&mut guard.blocker, NoneBlocked) { + // if our capacity is 0, then we need to wait for a receiver to be + // available to take our data. After waiting, we check again to make + // sure the port didn't go away in the meantime. If it did, we need + // to hand back our data. + NoneBlocked if guard.cap == 0 => { + let mut canceled = false; + assert!(guard.canceled.is_none()); + guard.canceled = Some(unsafe { mem::transmute(&mut canceled) }); + let mut guard = wait(&self.lock, guard, BlockedSender); + if canceled {Err(guard.buf.dequeue())} else {Ok(())} + } + + // success, we buffered some data + NoneBlocked => Ok(()), + + // success, someone's about to receive our buffered data. + BlockedReceiver(token) => { wakeup(token, guard); Ok(()) } + + BlockedSender(..) => panic!("lolwut"), + } + } + + pub fn try_send(&self, t: T) -> Result<(), super::TrySendError> { + let mut guard = self.lock.lock().unwrap(); + if guard.disconnected { + Err(super::TrySendError::Disconnected(t)) + } else if guard.buf.size() == guard.buf.cap() { + Err(super::TrySendError::Full(t)) + } else if guard.cap == 0 { + // With capacity 0, even though we have buffer space we can't + // transfer the data unless there's a receiver waiting. + match mem::replace(&mut guard.blocker, NoneBlocked) { + NoneBlocked => Err(super::TrySendError::Full(t)), + BlockedSender(..) => unreachable!(), + BlockedReceiver(token) => { + guard.buf.enqueue(t); + wakeup(token, guard); + Ok(()) + } + } + } else { + // If the buffer has some space and the capacity isn't 0, then we + // just enqueue the data for later retrieval, ensuring to wake up + // any blocked receiver if there is one. + assert!(guard.buf.size() < guard.buf.cap()); + guard.buf.enqueue(t); + match mem::replace(&mut guard.blocker, NoneBlocked) { + BlockedReceiver(token) => wakeup(token, guard), + NoneBlocked => {} + BlockedSender(..) => unreachable!(), + } + Ok(()) + } + } + + // Receives a message from this channel + // + // When reading this, remember that there can only ever be one receiver at + // time. + pub fn recv(&self, deadline: Option) -> Result { + let mut guard = self.lock.lock().unwrap(); + + let mut woke_up_after_waiting = false; + // Wait for the buffer to have something in it. No need for a + // while loop because we're the only receiver. + if !guard.disconnected && guard.buf.size() == 0 { + if let Some(deadline) = deadline { + guard = wait_timeout_receiver(&self.lock, + deadline, + guard, + &mut woke_up_after_waiting); + } else { + guard = wait(&self.lock, guard, BlockedReceiver); + woke_up_after_waiting = true; + } + } + + // NB: Channel could be disconnected while waiting, so the order of + // these conditionals is important. + if guard.disconnected && guard.buf.size() == 0 { + return Err(Disconnected); + } + + // Pick up the data, wake up our neighbors, and carry on + assert!(guard.buf.size() > 0 || (deadline.is_some() && !woke_up_after_waiting)); + + if guard.buf.size() == 0 { return Err(Empty); } + + let ret = guard.buf.dequeue(); + self.wakeup_senders(woke_up_after_waiting, guard); + Ok(ret) + } + + pub fn try_recv(&self) -> Result { + let mut guard = self.lock.lock().unwrap(); + + // Easy cases first + if guard.disconnected && guard.buf.size() == 0 { return Err(Disconnected) } + if guard.buf.size() == 0 { return Err(Empty) } + + // Be sure to wake up neighbors + let ret = Ok(guard.buf.dequeue()); + self.wakeup_senders(false, guard); + ret + } + + // Wake up pending senders after some data has been received + // + // * `waited` - flag if the receiver blocked to receive some data, or if it + // just picked up some data on the way out + // * `guard` - the lock guard that is held over this channel's lock + fn wakeup_senders(&self, waited: bool, mut guard: MutexGuard>) { + let pending_sender1: Option = guard.queue.dequeue(); + + // If this is a no-buffer channel (cap == 0), then if we didn't wait we + // need to ACK the sender. If we waited, then the sender waking us up + // was already the ACK. + let pending_sender2 = if guard.cap == 0 && !waited { + match mem::replace(&mut guard.blocker, NoneBlocked) { + NoneBlocked => None, + BlockedReceiver(..) => unreachable!(), + BlockedSender(token) => { + guard.canceled.take(); + Some(token) + } + } + } else { + None + }; + mem::drop(guard); + + // only outside of the lock do we wake up the pending threads + pending_sender1.map(|t| t.signal()); + pending_sender2.map(|t| t.signal()); + } + + // Prepares this shared packet for a channel clone, essentially just bumping + // a refcount. + pub fn clone_chan(&self) { + let old_count = self.channels.fetch_add(1, Ordering::SeqCst); + + // See comments on Arc::clone() on why we do this (for `mem::forget`). + if old_count > MAX_REFCOUNT { + unsafe { + abort(); + } + } + } + + pub fn drop_chan(&self) { + // Only flag the channel as disconnected if we're the last channel + match self.channels.fetch_sub(1, Ordering::SeqCst) { + 1 => {} + _ => return + } + + // Not much to do other than wake up a receiver if one's there + let mut guard = self.lock.lock().unwrap(); + if guard.disconnected { return } + guard.disconnected = true; + match mem::replace(&mut guard.blocker, NoneBlocked) { + NoneBlocked => {} + BlockedSender(..) => unreachable!(), + BlockedReceiver(token) => wakeup(token, guard), + } + } + + pub fn drop_port(&self) { + let mut guard = self.lock.lock().unwrap(); + + if guard.disconnected { return } + guard.disconnected = true; + + // If the capacity is 0, then the sender may want its data back after + // we're disconnected. Otherwise it's now our responsibility to destroy + // the buffered data. As with many other portions of this code, this + // needs to be careful to destroy the data *outside* of the lock to + // prevent deadlock. + let _data = if guard.cap != 0 { + mem::replace(&mut guard.buf.buf, Vec::new()) + } else { + Vec::new() + }; + let mut queue = mem::replace(&mut guard.queue, Queue { + head: ptr::null_mut(), + tail: ptr::null_mut(), + }); + + let waiter = match mem::replace(&mut guard.blocker, NoneBlocked) { + NoneBlocked => None, + BlockedSender(token) => { + *guard.canceled.take().unwrap() = true; + Some(token) + } + BlockedReceiver(..) => unreachable!(), + }; + mem::drop(guard); + + while let Some(token) = queue.dequeue() { token.signal(); } + waiter.map(|t| t.signal()); + } + + //////////////////////////////////////////////////////////////////////////// + // select implementation + //////////////////////////////////////////////////////////////////////////// + + // If Ok, the value is whether this port has data, if Err, then the upgraded + // port needs to be checked instead of this one. + pub fn can_recv(&self) -> bool { + let guard = self.lock.lock().unwrap(); + guard.disconnected || guard.buf.size() > 0 + } + + // Attempts to start selection on this port. This can either succeed or fail + // because there is data waiting. + pub fn start_selection(&self, token: SignalToken) -> StartResult { + let mut guard = self.lock.lock().unwrap(); + if guard.disconnected || guard.buf.size() > 0 { + Abort + } else { + match mem::replace(&mut guard.blocker, BlockedReceiver(token)) { + NoneBlocked => {} + BlockedSender(..) => unreachable!(), + BlockedReceiver(..) => unreachable!(), + } + Installed + } + } + + // Remove a previous selecting thread from this port. This ensures that the + // blocked thread will no longer be visible to any other threads. + // + // The return value indicates whether there's data on this port. + pub fn abort_selection(&self) -> bool { + let mut guard = self.lock.lock().unwrap(); + abort_selection(&mut guard) + } +} + +impl Drop for Packet { + fn drop(&mut self) { + assert_eq!(self.channels.load(Ordering::SeqCst), 0); + let mut guard = self.lock.lock().unwrap(); + assert!(guard.queue.dequeue().is_none()); + assert!(guard.canceled.is_none()); + } +} + + +//////////////////////////////////////////////////////////////////////////////// +// Buffer, a simple ring buffer backed by Vec +//////////////////////////////////////////////////////////////////////////////// + +impl Buffer { + fn enqueue(&mut self, t: T) { + let pos = (self.start + self.size) % self.buf.len(); + self.size += 1; + let prev = mem::replace(&mut self.buf[pos], Some(t)); + assert!(prev.is_none()); + } + + fn dequeue(&mut self) -> T { + let start = self.start; + self.size -= 1; + self.start = (self.start + 1) % self.buf.len(); + let result = &mut self.buf[start]; + result.take().unwrap() + } + + fn size(&self) -> usize { self.size } + fn cap(&self) -> usize { self.buf.len() } +} + +//////////////////////////////////////////////////////////////////////////////// +// Queue, a simple queue to enqueue threads with (stack-allocated nodes) +//////////////////////////////////////////////////////////////////////////////// + +impl Queue { + fn enqueue(&mut self, node: &mut Node) -> WaitToken { + let (wait_token, signal_token) = blocking::tokens(); + node.token = Some(signal_token); + node.next = ptr::null_mut(); + + if self.tail.is_null() { + self.head = node as *mut Node; + self.tail = node as *mut Node; + } else { + unsafe { + (*self.tail).next = node as *mut Node; + self.tail = node as *mut Node; + } + } + + wait_token + } + + fn dequeue(&mut self) -> Option { + if self.head.is_null() { + return None + } + let node = self.head; + self.head = unsafe { (*node).next }; + if self.head.is_null() { + self.tail = ptr::null_mut(); + } + unsafe { + (*node).next = ptr::null_mut(); + Some((*node).token.take().unwrap()) + } + } +} diff --git a/ctr-std/src/sync/mutex.rs b/ctr-std/src/sync/mutex.rs index 0d6ad5e..97b84d5 100644 --- a/ctr-std/src/sync/mutex.rs +++ b/ctr-std/src/sync/mutex.rs @@ -133,11 +133,13 @@ unsafe impl Sync for Mutex { } /// dropped (falls out of scope), the lock will be unlocked. /// /// The data protected by the mutex can be access through this guard via its -/// `Deref` and `DerefMut` implementations. +/// [`Deref`] and [`DerefMut`] implementations. /// /// This structure is created by the [`lock()`] and [`try_lock()`] methods on /// [`Mutex`]. /// +/// [`Deref`]: ../../std/ops/trait.Deref.html +/// [`DerefMut`]: ../../std/ops/trait.DerefMut.html /// [`lock()`]: struct.Mutex.html#method.lock /// [`try_lock()`]: struct.Mutex.html#method.try_lock /// [`Mutex`]: struct.Mutex.html diff --git a/ctr-std/src/sync/once.rs b/ctr-std/src/sync/once.rs new file mode 100644 index 0000000..1e7394c --- /dev/null +++ b/ctr-std/src/sync/once.rs @@ -0,0 +1,496 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +//! A "once initialization" primitive +//! +//! This primitive is meant to be used to run one-time initialization. An +//! example use case would be for initializing an FFI library. + +// A "once" is a relatively simple primitive, and it's also typically provided +// by the OS as well (see `pthread_once` or `InitOnceExecuteOnce`). The OS +// primitives, however, tend to have surprising restrictions, such as the Unix +// one doesn't allow an argument to be passed to the function. +// +// As a result, we end up implementing it ourselves in the standard library. +// This also gives us the opportunity to optimize the implementation a bit which +// should help the fast path on call sites. Consequently, let's explain how this +// primitive works now! +// +// So to recap, the guarantees of a Once are that it will call the +// initialization closure at most once, and it will never return until the one +// that's running has finished running. This means that we need some form of +// blocking here while the custom callback is running at the very least. +// Additionally, we add on the restriction of **poisoning**. Whenever an +// initialization closure panics, the Once enters a "poisoned" state which means +// that all future calls will immediately panic as well. +// +// So to implement this, one might first reach for a `StaticMutex`, but those +// unfortunately need to be deallocated (e.g. call `destroy()`) to free memory +// on all OSes (some of the BSDs allocate memory for mutexes). It also gets a +// lot harder with poisoning to figure out when the mutex needs to be +// deallocated because it's not after the closure finishes, but after the first +// successful closure finishes. +// +// All in all, this is instead implemented with atomics and lock-free +// operations! Whee! Each `Once` has one word of atomic state, and this state is +// CAS'd on to determine what to do. There are four possible state of a `Once`: +// +// * Incomplete - no initialization has run yet, and no thread is currently +// using the Once. +// * Poisoned - some thread has previously attempted to initialize the Once, but +// it panicked, so the Once is now poisoned. There are no other +// threads currently accessing this Once. +// * Running - some thread is currently attempting to run initialization. It may +// succeed, so all future threads need to wait for it to finish. +// Note that this state is accompanied with a payload, described +// below. +// * Complete - initialization has completed and all future calls should finish +// immediately. +// +// With 4 states we need 2 bits to encode this, and we use the remaining bits +// in the word we have allocated as a queue of threads waiting for the thread +// responsible for entering the RUNNING state. This queue is just a linked list +// of Waiter nodes which is monotonically increasing in size. Each node is +// allocated on the stack, and whenever the running closure finishes it will +// consume the entire queue and notify all waiters they should try again. +// +// You'll find a few more details in the implementation, but that's the gist of +// it! + +use fmt; +use marker; +use ptr; +use sync::atomic::{AtomicUsize, AtomicBool, Ordering}; +use thread::{self, Thread}; + +/// A synchronization primitive which can be used to run a one-time global +/// initialization. Useful for one-time initialization for FFI or related +/// functionality. This type can only be constructed with the `ONCE_INIT` +/// value. +/// +/// # Examples +/// +/// ``` +/// use std::sync::{Once, ONCE_INIT}; +/// +/// static START: Once = ONCE_INIT; +/// +/// START.call_once(|| { +/// // run initialization here +/// }); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct Once { + // This `state` word is actually an encoded version of just a pointer to a + // `Waiter`, so we add the `PhantomData` appropriately. + state: AtomicUsize, + _marker: marker::PhantomData<*mut Waiter>, +} + +// The `PhantomData` of a raw pointer removes these two auto traits, but we +// enforce both below in the implementation so this should be safe to add. +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl Sync for Once {} +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl Send for Once {} + +/// State yielded to the `call_once_force` method which can be used to query +/// whether the `Once` was previously poisoned or not. +#[unstable(feature = "once_poison", issue = "33577")] +#[derive(Debug)] +pub struct OnceState { + poisoned: bool, +} + +/// Initialization value for static `Once` values. +#[stable(feature = "rust1", since = "1.0.0")] +pub const ONCE_INIT: Once = Once::new(); + +// Four states that a Once can be in, encoded into the lower bits of `state` in +// the Once structure. +const INCOMPLETE: usize = 0x0; +const POISONED: usize = 0x1; +const RUNNING: usize = 0x2; +const COMPLETE: usize = 0x3; + +// Mask to learn about the state. All other bits are the queue of waiters if +// this is in the RUNNING state. +const STATE_MASK: usize = 0x3; + +// Representation of a node in the linked list of waiters in the RUNNING state. +struct Waiter { + thread: Option, + signaled: AtomicBool, + next: *mut Waiter, +} + +// Helper struct used to clean up after a closure call with a `Drop` +// implementation to also run on panic. +struct Finish { + panicked: bool, + me: &'static Once, +} + +impl Once { + /// Creates a new `Once` value. + #[stable(feature = "once_new", since = "1.2.0")] + pub const fn new() -> Once { + Once { + state: AtomicUsize::new(INCOMPLETE), + _marker: marker::PhantomData, + } + } + + /// Performs an initialization routine once and only once. The given closure + /// will be executed if this is the first time `call_once` has been called, + /// and otherwise the routine will *not* be invoked. + /// + /// This method will block the calling thread if another initialization + /// routine is currently running. + /// + /// When this function returns, it is guaranteed that some initialization + /// has run and completed (it may not be the closure specified). It is also + /// guaranteed that any memory writes performed by the executed closure can + /// be reliably observed by other threads at this point (there is a + /// happens-before relation between the closure and code executing after the + /// return). + /// + /// # Examples + /// + /// ``` + /// use std::sync::{Once, ONCE_INIT}; + /// + /// static mut VAL: usize = 0; + /// static INIT: Once = ONCE_INIT; + /// + /// // Accessing a `static mut` is unsafe much of the time, but if we do so + /// // in a synchronized fashion (e.g. write once or read all) then we're + /// // good to go! + /// // + /// // This function will only call `expensive_computation` once, and will + /// // otherwise always return the value returned from the first invocation. + /// fn get_cached_val() -> usize { + /// unsafe { + /// INIT.call_once(|| { + /// VAL = expensive_computation(); + /// }); + /// VAL + /// } + /// } + /// + /// fn expensive_computation() -> usize { + /// // ... + /// # 2 + /// } + /// ``` + /// + /// # Panics + /// + /// The closure `f` will only be executed once if this is called + /// concurrently amongst many threads. If that closure panics, however, then + /// it will *poison* this `Once` instance, causing all future invocations of + /// `call_once` to also panic. + /// + /// This is similar to [poisoning with mutexes][poison]. + /// + /// [poison]: struct.Mutex.html#poisoning + #[stable(feature = "rust1", since = "1.0.0")] + pub fn call_once(&'static self, f: F) where F: FnOnce() { + // Fast path, just see if we've completed initialization. + if self.state.load(Ordering::SeqCst) == COMPLETE { + return + } + + let mut f = Some(f); + self.call_inner(false, &mut |_| f.take().unwrap()()); + } + + /// Performs the same function as `call_once` except ignores poisoning. + /// + /// If this `Once` has been poisoned (some initialization panicked) then + /// this function will continue to attempt to call initialization functions + /// until one of them doesn't panic. + /// + /// The closure `f` is yielded a structure which can be used to query the + /// state of this `Once` (whether initialization has previously panicked or + /// not). + #[unstable(feature = "once_poison", issue = "33577")] + pub fn call_once_force(&'static self, f: F) where F: FnOnce(&OnceState) { + // same as above, just with a different parameter to `call_inner`. + if self.state.load(Ordering::SeqCst) == COMPLETE { + return + } + + let mut f = Some(f); + self.call_inner(true, &mut |p| { + f.take().unwrap()(&OnceState { poisoned: p }) + }); + } + + // This is a non-generic function to reduce the monomorphization cost of + // using `call_once` (this isn't exactly a trivial or small implementation). + // + // Additionally, this is tagged with `#[cold]` as it should indeed be cold + // and it helps let LLVM know that calls to this function should be off the + // fast path. Essentially, this should help generate more straight line code + // in LLVM. + // + // Finally, this takes an `FnMut` instead of a `FnOnce` because there's + // currently no way to take an `FnOnce` and call it via virtual dispatch + // without some allocation overhead. + #[cold] + fn call_inner(&'static self, + ignore_poisoning: bool, + mut init: &mut FnMut(bool)) { + let mut state = self.state.load(Ordering::SeqCst); + + 'outer: loop { + match state { + // If we're complete, then there's nothing to do, we just + // jettison out as we shouldn't run the closure. + COMPLETE => return, + + // If we're poisoned and we're not in a mode to ignore + // poisoning, then we panic here to propagate the poison. + POISONED if !ignore_poisoning => { + panic!("Once instance has previously been poisoned"); + } + + // Otherwise if we see a poisoned or otherwise incomplete state + // we will attempt to move ourselves into the RUNNING state. If + // we succeed, then the queue of waiters starts at null (all 0 + // bits). + POISONED | + INCOMPLETE => { + let old = self.state.compare_and_swap(state, RUNNING, + Ordering::SeqCst); + if old != state { + state = old; + continue + } + + // Run the initialization routine, letting it know if we're + // poisoned or not. The `Finish` struct is then dropped, and + // the `Drop` implementation here is responsible for waking + // up other waiters both in the normal return and panicking + // case. + let mut complete = Finish { + panicked: true, + me: self, + }; + init(state == POISONED); + complete.panicked = false; + return + } + + // All other values we find should correspond to the RUNNING + // state with an encoded waiter list in the more significant + // bits. We attempt to enqueue ourselves by moving us to the + // head of the list and bail out if we ever see a state that's + // not RUNNING. + _ => { + assert!(state & STATE_MASK == RUNNING); + let mut node = Waiter { + thread: Some(thread::current()), + signaled: AtomicBool::new(false), + next: ptr::null_mut(), + }; + let me = &mut node as *mut Waiter as usize; + assert!(me & STATE_MASK == 0); + + while state & STATE_MASK == RUNNING { + node.next = (state & !STATE_MASK) as *mut Waiter; + let old = self.state.compare_and_swap(state, + me | RUNNING, + Ordering::SeqCst); + if old != state { + state = old; + continue + } + + // Once we've enqueued ourselves, wait in a loop. + // Afterwards reload the state and continue with what we + // were doing from before. + while !node.signaled.load(Ordering::SeqCst) { + thread::park(); + } + state = self.state.load(Ordering::SeqCst); + continue 'outer + } + } + } + } + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for Once { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.pad("Once { .. }") + } +} + +impl Drop for Finish { + fn drop(&mut self) { + // Swap out our state with however we finished. We should only ever see + // an old state which was RUNNING. + let queue = if self.panicked { + self.me.state.swap(POISONED, Ordering::SeqCst) + } else { + self.me.state.swap(COMPLETE, Ordering::SeqCst) + }; + assert_eq!(queue & STATE_MASK, RUNNING); + + // Decode the RUNNING to a list of waiters, then walk that entire list + // and wake them up. Note that it is crucial that after we store `true` + // in the node it can be free'd! As a result we load the `thread` to + // signal ahead of time and then unpark it after the store. + unsafe { + let mut queue = (queue & !STATE_MASK) as *mut Waiter; + while !queue.is_null() { + let next = (*queue).next; + let thread = (*queue).thread.take().unwrap(); + (*queue).signaled.store(true, Ordering::SeqCst); + thread.unpark(); + queue = next; + } + } + } +} + +impl OnceState { + /// Returns whether the associated `Once` has been poisoned. + /// + /// Once an initalization routine for a `Once` has panicked it will forever + /// indicate to future forced initialization routines that it is poisoned. + #[unstable(feature = "once_poison", issue = "33577")] + pub fn poisoned(&self) -> bool { + self.poisoned + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use panic; + use sync::mpsc::channel; + use thread; + use super::Once; + + #[test] + fn smoke_once() { + static O: Once = Once::new(); + let mut a = 0; + O.call_once(|| a += 1); + assert_eq!(a, 1); + O.call_once(|| a += 1); + assert_eq!(a, 1); + } + + #[test] + fn stampede_once() { + static O: Once = Once::new(); + static mut RUN: bool = false; + + let (tx, rx) = channel(); + for _ in 0..10 { + let tx = tx.clone(); + thread::spawn(move|| { + for _ in 0..4 { thread::yield_now() } + unsafe { + O.call_once(|| { + assert!(!RUN); + RUN = true; + }); + assert!(RUN); + } + tx.send(()).unwrap(); + }); + } + + unsafe { + O.call_once(|| { + assert!(!RUN); + RUN = true; + }); + assert!(RUN); + } + + for _ in 0..10 { + rx.recv().unwrap(); + } + } + + #[test] + fn poison_bad() { + static O: Once = Once::new(); + + // poison the once + let t = panic::catch_unwind(|| { + O.call_once(|| panic!()); + }); + assert!(t.is_err()); + + // poisoning propagates + let t = panic::catch_unwind(|| { + O.call_once(|| {}); + }); + assert!(t.is_err()); + + // we can subvert poisoning, however + let mut called = false; + O.call_once_force(|p| { + called = true; + assert!(p.poisoned()) + }); + assert!(called); + + // once any success happens, we stop propagating the poison + O.call_once(|| {}); + } + + #[test] + fn wait_for_force_to_finish() { + static O: Once = Once::new(); + + // poison the once + let t = panic::catch_unwind(|| { + O.call_once(|| panic!()); + }); + assert!(t.is_err()); + + // make sure someone's waiting inside the once via a force + let (tx1, rx1) = channel(); + let (tx2, rx2) = channel(); + let t1 = thread::spawn(move || { + O.call_once_force(|p| { + assert!(p.poisoned()); + tx1.send(()).unwrap(); + rx2.recv().unwrap(); + }); + }); + + rx1.recv().unwrap(); + + // put another waiter on the once + let t2 = thread::spawn(|| { + let mut called = false; + O.call_once(|| { + called = true; + }); + assert!(!called); + }); + + tx2.send(()).unwrap(); + + assert!(t1.join().is_ok()); + assert!(t2.join().is_ok()); + + } +} diff --git a/ctr-std/src/sync/rwlock.rs b/ctr-std/src/sync/rwlock.rs new file mode 100644 index 0000000..a3db0ad --- /dev/null +++ b/ctr-std/src/sync/rwlock.rs @@ -0,0 +1,666 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use cell::UnsafeCell; +use fmt; +use marker; +use mem; +use ops::{Deref, DerefMut}; +use ptr; +use sys_common::poison::{self, LockResult, TryLockError, TryLockResult}; +use sys_common::rwlock as sys; + +/// A reader-writer lock +/// +/// This type of lock allows a number of readers or at most one writer at any +/// point in time. The write portion of this lock typically allows modification +/// of the underlying data (exclusive access) and the read portion of this lock +/// typically allows for read-only access (shared access). +/// +/// The priority policy of the lock is dependent on the underlying operating +/// system's implementation, and this type does not guarantee that any +/// particular policy will be used. +/// +/// The type parameter `T` represents the data that this lock protects. It is +/// required that `T` satisfies `Send` to be shared across threads and `Sync` to +/// allow concurrent access through readers. The RAII guards returned from the +/// locking methods implement `Deref` (and `DerefMut` for the `write` methods) +/// to allow access to the contained of the lock. +/// +/// # Poisoning +/// +/// An `RwLock`, like `Mutex`, will become poisoned on a panic. Note, however, +/// that an `RwLock` may only be poisoned if a panic occurs while it is locked +/// exclusively (write mode). If a panic occurs in any reader, then the lock +/// will not be poisoned. +/// +/// # Examples +/// +/// ``` +/// use std::sync::RwLock; +/// +/// let lock = RwLock::new(5); +/// +/// // many reader locks can be held at once +/// { +/// let r1 = lock.read().unwrap(); +/// let r2 = lock.read().unwrap(); +/// assert_eq!(*r1, 5); +/// assert_eq!(*r2, 5); +/// } // read locks are dropped at this point +/// +/// // only one write lock may be held, however +/// { +/// let mut w = lock.write().unwrap(); +/// *w += 1; +/// assert_eq!(*w, 6); +/// } // write lock is dropped here +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RwLock { + inner: Box, + poison: poison::Flag, + data: UnsafeCell, +} + +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl Send for RwLock {} +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl Sync for RwLock {} + +/// RAII structure used to release the shared read access of a lock when +/// dropped. +/// +/// This structure is created by the [`read()`] and [`try_read()`] methods on +/// [`RwLock`]. +/// +/// [`read()`]: struct.RwLock.html#method.read +/// [`try_read()`]: struct.RwLock.html#method.try_read +/// [`RwLock`]: struct.RwLock.html +#[must_use] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RwLockReadGuard<'a, T: ?Sized + 'a> { + __lock: &'a RwLock, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'a, T: ?Sized> !marker::Send for RwLockReadGuard<'a, T> {} + +/// RAII structure used to release the exclusive write access of a lock when +/// dropped. +/// +/// This structure is created by the [`write()`] and [`try_write()`] methods +/// on [`RwLock`]. +/// +/// [`write()`]: struct.RwLock.html#method.write +/// [`try_write()`]: struct.RwLock.html#method.try_write +/// [`RwLock`]: struct.RwLock.html +#[must_use] +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> { + __lock: &'a RwLock, + __poison: poison::Guard, +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'a, T: ?Sized> !marker::Send for RwLockWriteGuard<'a, T> {} + +impl RwLock { + /// Creates a new instance of an `RwLock` which is unlocked. + /// + /// # Examples + /// + /// ``` + /// use std::sync::RwLock; + /// + /// let lock = RwLock::new(5); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn new(t: T) -> RwLock { + RwLock { + inner: box sys::RWLock::new(), + poison: poison::Flag::new(), + data: UnsafeCell::new(t), + } + } +} + +impl RwLock { + /// Locks this rwlock with shared read access, blocking the current thread + /// until it can be acquired. + /// + /// The calling thread will be blocked until there are no more writers which + /// hold the lock. There may be other readers currently inside the lock when + /// this method returns. This method does not provide any guarantees with + /// respect to the ordering of whether contentious readers or writers will + /// acquire the lock first. + /// + /// Returns an RAII guard which will release this thread's shared access + /// once it is dropped. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. + /// The failure will occur immediately after the lock has been acquired. + /// + /// # Panics + /// + /// This function might panic when called if the lock is already held by the current thread. + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn read(&self) -> LockResult> { + unsafe { + self.inner.read(); + RwLockReadGuard::new(self) + } + } + + /// Attempts to acquire this rwlock with shared read access. + /// + /// If the access could not be granted at this time, then `Err` is returned. + /// Otherwise, an RAII guard is returned which will release the shared access + /// when it is dropped. + /// + /// This function does not block. + /// + /// This function does not provide any guarantees with respect to the ordering + /// of whether contentious readers or writers will acquire the lock first. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn try_read(&self) -> TryLockResult> { + unsafe { + if self.inner.try_read() { + Ok(RwLockReadGuard::new(self)?) + } else { + Err(TryLockError::WouldBlock) + } + } + } + + /// Locks this rwlock with exclusive write access, blocking the current + /// thread until it can be acquired. + /// + /// This function will not return while other writers or other readers + /// currently have access to the lock. + /// + /// Returns an RAII guard which will drop the write access of this rwlock + /// when dropped. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. + /// An error will be returned when the lock is acquired. + /// + /// # Panics + /// + /// This function might panic when called if the lock is already held by the current thread. + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn write(&self) -> LockResult> { + unsafe { + self.inner.write(); + RwLockWriteGuard::new(self) + } + } + + /// Attempts to lock this rwlock with exclusive write access. + /// + /// If the lock could not be acquired at this time, then `Err` is returned. + /// Otherwise, an RAII guard is returned which will release the lock when + /// it is dropped. + /// + /// This function does not block. + /// + /// This function does not provide any guarantees with respect to the ordering + /// of whether contentious readers or writers will acquire the lock first. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + #[inline] + #[stable(feature = "rust1", since = "1.0.0")] + pub fn try_write(&self) -> TryLockResult> { + unsafe { + if self.inner.try_write() { + Ok(RwLockWriteGuard::new(self)?) + } else { + Err(TryLockError::WouldBlock) + } + } + } + + /// Determines whether the lock is poisoned. + /// + /// If another thread is active, the lock can still become poisoned at any + /// time. You should not trust a `false` value for program correctness + /// without additional synchronization. + #[inline] + #[stable(feature = "sync_poison", since = "1.2.0")] + pub fn is_poisoned(&self) -> bool { + self.poison.get() + } + + /// Consumes this `RwLock`, returning the underlying data. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + #[stable(feature = "rwlock_into_inner", since = "1.6.0")] + pub fn into_inner(self) -> LockResult where T: Sized { + // We know statically that there are no outstanding references to + // `self` so there's no need to lock the inner lock. + // + // To get the inner value, we'd like to call `data.into_inner()`, + // but because `RwLock` impl-s `Drop`, we can't move out of it, so + // we'll have to destructure it manually instead. + unsafe { + // Like `let RwLock { inner, poison, data } = self`. + let (inner, poison, data) = { + let RwLock { ref inner, ref poison, ref data } = self; + (ptr::read(inner), ptr::read(poison), ptr::read(data)) + }; + mem::forget(self); + inner.destroy(); // Keep in sync with the `Drop` impl. + drop(inner); + + poison::map_result(poison.borrow(), |_| data.into_inner()) + } + } + + /// Returns a mutable reference to the underlying data. + /// + /// Since this call borrows the `RwLock` mutably, no actual locking needs to + /// take place---the mutable borrow statically guarantees no locks exist. + /// + /// # Errors + /// + /// This function will return an error if the RwLock is poisoned. An RwLock + /// is poisoned whenever a writer panics while holding an exclusive lock. An + /// error will only be returned if the lock would have otherwise been + /// acquired. + #[stable(feature = "rwlock_get_mut", since = "1.6.0")] + pub fn get_mut(&mut self) -> LockResult<&mut T> { + // We know statically that there are no other references to `self`, so + // there's no need to lock the inner lock. + let data = unsafe { &mut *self.data.get() }; + poison::map_result(self.poison.borrow(), |_| data) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl<#[may_dangle] T: ?Sized> Drop for RwLock { + fn drop(&mut self) { + // IMPORTANT: This code needs to be kept in sync with `RwLock::into_inner`. + unsafe { self.inner.destroy() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Debug for RwLock { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + match self.try_read() { + Ok(guard) => write!(f, "RwLock {{ data: {:?} }}", &*guard), + Err(TryLockError::Poisoned(err)) => { + write!(f, "RwLock {{ data: Poisoned({:?}) }}", &**err.get_ref()) + }, + Err(TryLockError::WouldBlock) => write!(f, "RwLock {{ }}") + } + } +} + +#[stable(feature = "rw_lock_default", since = "1.9.0")] +impl Default for RwLock { + /// Creates a new `RwLock`, with the `Default` value for T. + fn default() -> RwLock { + RwLock::new(Default::default()) + } +} + +impl<'rwlock, T: ?Sized> RwLockReadGuard<'rwlock, T> { + unsafe fn new(lock: &'rwlock RwLock) + -> LockResult> { + poison::map_result(lock.poison.borrow(), |_| { + RwLockReadGuard { + __lock: lock, + } + }) + } +} + +impl<'rwlock, T: ?Sized> RwLockWriteGuard<'rwlock, T> { + unsafe fn new(lock: &'rwlock RwLock) + -> LockResult> { + poison::map_result(lock.poison.borrow(), |guard| { + RwLockWriteGuard { + __lock: lock, + __poison: guard, + } + }) + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl<'a, T: fmt::Debug> fmt::Debug for RwLockReadGuard<'a, T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_struct("RwLockReadGuard") + .field("lock", &self.__lock) + .finish() + } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl<'a, T: fmt::Debug> fmt::Debug for RwLockWriteGuard<'a, T> { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.debug_struct("RwLockWriteGuard") + .field("lock", &self.__lock) + .finish() + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'rwlock, T: ?Sized> Deref for RwLockReadGuard<'rwlock, T> { + type Target = T; + + fn deref(&self) -> &T { + unsafe { &*self.__lock.data.get() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'rwlock, T: ?Sized> Deref for RwLockWriteGuard<'rwlock, T> { + type Target = T; + + fn deref(&self) -> &T { + unsafe { &*self.__lock.data.get() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'rwlock, T: ?Sized> DerefMut for RwLockWriteGuard<'rwlock, T> { + fn deref_mut(&mut self) -> &mut T { + unsafe { &mut *self.__lock.data.get() } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'a, T: ?Sized> Drop for RwLockReadGuard<'a, T> { + fn drop(&mut self) { + unsafe { self.__lock.inner.read_unlock(); } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'a, T: ?Sized> Drop for RwLockWriteGuard<'a, T> { + fn drop(&mut self) { + self.__lock.poison.done(&self.__poison); + unsafe { self.__lock.inner.write_unlock(); } + } +} + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + #![allow(deprecated)] // rand + + use rand::{self, Rng}; + use sync::mpsc::channel; + use thread; + use sync::{Arc, RwLock, TryLockError}; + use sync::atomic::{AtomicUsize, Ordering}; + + #[derive(Eq, PartialEq, Debug)] + struct NonCopy(i32); + + #[test] + fn smoke() { + let l = RwLock::new(()); + drop(l.read().unwrap()); + drop(l.write().unwrap()); + drop((l.read().unwrap(), l.read().unwrap())); + drop(l.write().unwrap()); + } + + #[test] + fn frob() { + const N: usize = 10; + const M: usize = 1000; + + let r = Arc::new(RwLock::new(())); + + let (tx, rx) = channel::<()>(); + for _ in 0..N { + let tx = tx.clone(); + let r = r.clone(); + thread::spawn(move || { + let mut rng = rand::thread_rng(); + for _ in 0..M { + if rng.gen_weighted_bool(N) { + drop(r.write().unwrap()); + } else { + drop(r.read().unwrap()); + } + } + drop(tx); + }); + } + drop(tx); + let _ = rx.recv(); + } + + #[test] + fn test_rw_arc_poison_wr() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move|| { + let _lock = arc2.write().unwrap(); + panic!(); + }).join(); + assert!(arc.read().is_err()); + } + + #[test] + fn test_rw_arc_poison_ww() { + let arc = Arc::new(RwLock::new(1)); + assert!(!arc.is_poisoned()); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move|| { + let _lock = arc2.write().unwrap(); + panic!(); + }).join(); + assert!(arc.write().is_err()); + assert!(arc.is_poisoned()); + } + + #[test] + fn test_rw_arc_no_poison_rr() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move|| { + let _lock = arc2.read().unwrap(); + panic!(); + }).join(); + let lock = arc.read().unwrap(); + assert_eq!(*lock, 1); + } + #[test] + fn test_rw_arc_no_poison_rw() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _: Result<(), _> = thread::spawn(move|| { + let _lock = arc2.read().unwrap(); + panic!() + }).join(); + let lock = arc.write().unwrap(); + assert_eq!(*lock, 1); + } + + #[test] + fn test_rw_arc() { + let arc = Arc::new(RwLock::new(0)); + let arc2 = arc.clone(); + let (tx, rx) = channel(); + + thread::spawn(move|| { + let mut lock = arc2.write().unwrap(); + for _ in 0..10 { + let tmp = *lock; + *lock = -1; + thread::yield_now(); + *lock = tmp + 1; + } + tx.send(()).unwrap(); + }); + + // Readers try to catch the writer in the act + let mut children = Vec::new(); + for _ in 0..5 { + let arc3 = arc.clone(); + children.push(thread::spawn(move|| { + let lock = arc3.read().unwrap(); + assert!(*lock >= 0); + })); + } + + // Wait for children to pass their asserts + for r in children { + assert!(r.join().is_ok()); + } + + // Wait for writer to finish + rx.recv().unwrap(); + let lock = arc.read().unwrap(); + assert_eq!(*lock, 10); + } + + #[test] + fn test_rw_arc_access_in_unwind() { + let arc = Arc::new(RwLock::new(1)); + let arc2 = arc.clone(); + let _ = thread::spawn(move|| -> () { + struct Unwinder { + i: Arc>, + } + impl Drop for Unwinder { + fn drop(&mut self) { + let mut lock = self.i.write().unwrap(); + *lock += 1; + } + } + let _u = Unwinder { i: arc2 }; + panic!(); + }).join(); + let lock = arc.read().unwrap(); + assert_eq!(*lock, 2); + } + + #[test] + fn test_rwlock_unsized() { + let rw: &RwLock<[i32]> = &RwLock::new([1, 2, 3]); + { + let b = &mut *rw.write().unwrap(); + b[0] = 4; + b[2] = 5; + } + let comp: &[i32] = &[4, 2, 5]; + assert_eq!(&*rw.read().unwrap(), comp); + } + + #[test] + fn test_rwlock_try_write() { + let lock = RwLock::new(0isize); + let read_guard = lock.read().unwrap(); + + let write_result = lock.try_write(); + match write_result { + Err(TryLockError::WouldBlock) => (), + Ok(_) => assert!(false, "try_write should not succeed while read_guard is in scope"), + Err(_) => assert!(false, "unexpected error"), + } + + drop(read_guard); + } + + #[test] + fn test_into_inner() { + let m = RwLock::new(NonCopy(10)); + assert_eq!(m.into_inner().unwrap(), NonCopy(10)); + } + + #[test] + fn test_into_inner_drop() { + struct Foo(Arc); + impl Drop for Foo { + fn drop(&mut self) { + self.0.fetch_add(1, Ordering::SeqCst); + } + } + let num_drops = Arc::new(AtomicUsize::new(0)); + let m = RwLock::new(Foo(num_drops.clone())); + assert_eq!(num_drops.load(Ordering::SeqCst), 0); + { + let _inner = m.into_inner().unwrap(); + assert_eq!(num_drops.load(Ordering::SeqCst), 0); + } + assert_eq!(num_drops.load(Ordering::SeqCst), 1); + } + + #[test] + fn test_into_inner_poison() { + let m = Arc::new(RwLock::new(NonCopy(10))); + let m2 = m.clone(); + let _ = thread::spawn(move || { + let _lock = m2.write().unwrap(); + panic!("test panic in inner thread to poison RwLock"); + }).join(); + + assert!(m.is_poisoned()); + match Arc::try_unwrap(m).unwrap().into_inner() { + Err(e) => assert_eq!(e.into_inner(), NonCopy(10)), + Ok(x) => panic!("into_inner of poisoned RwLock is Ok: {:?}", x), + } + } + + #[test] + fn test_get_mut() { + let mut m = RwLock::new(NonCopy(10)); + *m.get_mut().unwrap() = NonCopy(20); + assert_eq!(m.into_inner().unwrap(), NonCopy(20)); + } + + #[test] + fn test_get_mut_poison() { + let m = Arc::new(RwLock::new(NonCopy(10))); + let m2 = m.clone(); + let _ = thread::spawn(move || { + let _lock = m2.write().unwrap(); + panic!("test panic in inner thread to poison RwLock"); + }).join(); + + assert!(m.is_poisoned()); + match Arc::try_unwrap(m).unwrap().get_mut() { + Err(e) => assert_eq!(*e.into_inner(), NonCopy(10)), + Ok(x) => panic!("get_mut of poisoned RwLock is Ok: {:?}", x), + } + } +} diff --git a/ctr-std/src/sys/unix/condvar.rs b/ctr-std/src/sys/unix/condvar.rs new file mode 100644 index 0000000..f19922c --- /dev/null +++ b/ctr-std/src/sys/unix/condvar.rs @@ -0,0 +1,111 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// *Implementation adapted from `/sys/redox/condvar.rs` + +use cell::UnsafeCell; +use intrinsics::atomic_cxchg; +use ptr; +use time::Duration; + +use sys::mutex::{self, Mutex}; + +use libctru::synchronization::{__sync_get_arbiter, LightLock}; +use libctru::svc::{svcArbitrateAddress, ArbitrationType}; + +pub struct Condvar { + lock: UnsafeCell<*mut LightLock>, +} + +unsafe impl Send for Condvar {} +unsafe impl Sync for Condvar {} + +impl Condvar { + pub const fn new() -> Condvar { + Condvar { + lock: UnsafeCell::new(ptr::null_mut()), + } + } + + #[inline] + pub unsafe fn init(&self) { + *self.lock.get() = ptr::null_mut(); + } + + #[inline] + pub fn notify_one(&self) { + unsafe { + let arbiter = __sync_get_arbiter(); + + svcArbitrateAddress(arbiter, + *self.lock.get() as u32, + ArbitrationType::ARBITRATION_SIGNAL, + 1, + 0); + } + } + + #[inline] + pub fn notify_all(&self) { + unsafe { + let lock = self.lock.get(); + + if *lock == ptr::null_mut() { + return; + } + + let arbiter = __sync_get_arbiter(); + + svcArbitrateAddress(arbiter, + *self.lock.get() as u32, + ArbitrationType::ARBITRATION_SIGNAL, + -1, + 0); + } + } + + #[inline] + pub fn wait(&self, mutex: &Mutex) { + unsafe { + let lock = self.lock.get(); + + if *lock != mutex::raw(mutex) { + if *lock != ptr::null_mut() { + panic!("Condvar used with more than one Mutex"); + } + + atomic_cxchg(lock as *mut usize, 0, mutex::raw(mutex) as usize); + } + + mutex.unlock(); + + let arbiter = __sync_get_arbiter(); + + svcArbitrateAddress(arbiter, + *self.lock.get() as u32, + ArbitrationType::ARBITRATION_WAIT_IF_LESS_THAN, + 0, + 0); + + mutex.lock(); + } + } + + #[inline] + pub fn wait_timeout(&self, _mutex: &Mutex, _dur: Duration) -> bool { + ::sys_common::util::dumb_print(format_args!("condvar wait_timeout\n")); + unimplemented!(); + } + + #[inline] + pub unsafe fn destroy(&self) { + *self.lock.get() = ptr::null_mut(); + } +} diff --git a/ctr-std/src/sys/unix/mod.rs b/ctr-std/src/sys/unix/mod.rs index 0da1d3b..76a4555 100644 --- a/ctr-std/src/sys/unix/mod.rs +++ b/ctr-std/src/sys/unix/mod.rs @@ -13,6 +13,7 @@ use io::{self, ErrorKind}; use libc; +pub mod condvar; pub mod ext; pub mod fast_thread_local; pub mod fd; @@ -22,6 +23,8 @@ pub mod mutex; pub mod os; pub mod os_str; pub mod path; +pub mod rwlock; +pub mod thread; pub mod thread_local; pub mod time; diff --git a/ctr-std/src/sys/unix/rwlock.rs b/ctr-std/src/sys/unix/rwlock.rs new file mode 100644 index 0000000..d74b614 --- /dev/null +++ b/ctr-std/src/sys/unix/rwlock.rs @@ -0,0 +1,61 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use super::mutex::Mutex; + +pub struct RWLock { + mutex: Mutex +} + +unsafe impl Send for RWLock {} +unsafe impl Sync for RWLock {} + +impl RWLock { + pub const fn new() -> RWLock { + RWLock { + mutex: Mutex::new() + } + } + + #[inline] + pub unsafe fn read(&self) { + self.mutex.lock(); + } + + #[inline] + pub unsafe fn try_read(&self) -> bool { + self.mutex.try_lock() + } + + #[inline] + pub unsafe fn write(&self) { + self.mutex.lock(); + } + + #[inline] + pub unsafe fn try_write(&self) -> bool { + self.mutex.try_lock() + } + + #[inline] + pub unsafe fn read_unlock(&self) { + self.mutex.unlock(); + } + + #[inline] + pub unsafe fn write_unlock(&self) { + self.mutex.unlock(); + } + + #[inline] + pub unsafe fn destroy(&self) { + self.mutex.destroy(); + } +} diff --git a/ctr-std/src/sys/unix/thread.rs b/ctr-std/src/sys/unix/thread.rs new file mode 100644 index 0000000..572ac72 --- /dev/null +++ b/ctr-std/src/sys/unix/thread.rs @@ -0,0 +1,97 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use alloc::boxed::FnBox; +use libc; +use cmp; +use ffi::CStr; +use io; +use mem; +use ptr; +use sys_common::thread::start_thread; +use time::Duration; + +use libctru::svc::{svcSleepThread, svcGetThreadPriority}; +use libctru::thread::{threadCreate, threadJoin, threadFree}; +use libctru::thread::Thread as ThreadHandle; + +pub struct Thread { + handle: ThreadHandle, +} + +// Some platforms may have pthread_t as a pointer in which case we still want +// a thread to be Send/Sync +unsafe impl Send for Thread {} +unsafe impl Sync for Thread {} + +impl Thread { + pub unsafe fn new<'a>(stack: usize, p: Box) -> io::Result { + let p = box p; + let stack_size = cmp::max(stack, 0x10000); + + // this retrieves the main thread's priority value. child threads need + // to be spawned with a greater priority (smaller priority value) than + // the main thread + let mut priority = 0; + svcGetThreadPriority(&mut priority, 0xFFFF8000); + priority -= 1; + + let handle = threadCreate(Some(thread_func), &*p as *const _ as *mut _, + stack_size, priority, -2, 0); + + return if handle == ptr::null_mut() { + Err(io::Error::from_raw_os_error(libc::EAGAIN)) + } else { + mem::forget(p); // ownership passed to the new thread + Ok(Thread { handle: handle }) + }; + + extern "C" fn thread_func(start: *mut libc::c_void) { + unsafe { start_thread(start) } + } + } + + pub fn yield_now() { + unimplemented!() + } + + pub fn set_name(_name: &CStr) { + // can't set thread names on the 3DS + } + + pub fn sleep(dur: Duration) { + unsafe { + let nanos = dur.as_secs() * 1_000_000_000 + dur.subsec_nanos() as u64; + svcSleepThread(nanos as i64) + } + } + + pub fn join(self) { + unsafe { + let ret = threadJoin(self.handle, u64::max_value()); + threadFree(self.handle); + mem::forget(self); + debug_assert_eq!(ret, 0); + } + } + + pub fn id(&self) -> usize { + unimplemented!() + } + + pub fn into_id(self) -> usize { + unimplemented!() + } +} + +pub mod guard { + pub unsafe fn current() -> Option { None } + pub unsafe fn init() -> Option { None } +} diff --git a/ctr-std/src/sys/unix/time.rs b/ctr-std/src/sys/unix/time.rs index 052bd32..e8c0632 100644 --- a/ctr-std/src/sys/unix/time.rs +++ b/ctr-std/src/sys/unix/time.rs @@ -106,6 +106,7 @@ impl Ord for Timespec { mod inner { use fmt; use libc; + use sync::Once; use sys::cvt; use sys_common::mul_div_u64; use time::Duration; @@ -113,7 +114,6 @@ mod inner { use super::NSEC_PER_SEC; use super::Timespec; - use spin; use libctru; #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)] @@ -164,7 +164,7 @@ mod inner { } // The initial system tick after which all Instants occur - static TICK: spin::Once = spin::Once::new(); + static mut TICK: u64 = 0; // A source of monotonic time based on ticks of the 3DS CPU. Returns the // number of system ticks elapsed since an arbitrary point in the past @@ -180,7 +180,13 @@ mod inner { // subsequent calls to this function return the previously generated // tick value fn get_first_tick() -> u64 { - *TICK.call_once(get_system_tick) + static ONCE: Once = Once::new(); + unsafe { + ONCE.call_once(|| { + TICK = get_system_tick(); + }); + TICK + } } // Gets the current system tick @@ -201,11 +207,12 @@ mod inner { // on a New 3DS running in 804MHz mode // // See https://www.3dbrew.org/wiki/Hardware#Common_hardware - fn info() -> CtrClockInfo { - CtrClockInfo { + fn info() -> &'static CtrClockInfo { + static INFO: CtrClockInfo = CtrClockInfo { numer: 1_000_000_000, denom: 268_111_856, - } + }; + &INFO } fn dur2intervals(dur: &Duration) -> u64 { diff --git a/ctr-std/src/sys_common/condvar.rs b/ctr-std/src/sys_common/condvar.rs new file mode 100644 index 0000000..b6f29dd --- /dev/null +++ b/ctr-std/src/sys_common/condvar.rs @@ -0,0 +1,70 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use time::Duration; +use sys_common::mutex::{self, Mutex}; +use sys::condvar as imp; + +/// An OS-based condition variable. +/// +/// This structure is the lowest layer possible on top of the OS-provided +/// condition variables. It is consequently entirely unsafe to use. It is +/// recommended to use the safer types at the top level of this crate instead of +/// this type. +pub struct Condvar(imp::Condvar); + +impl Condvar { + /// Creates a new condition variable for use. + /// + /// Behavior is undefined if the condition variable is moved after it is + /// first used with any of the functions below. + pub const fn new() -> Condvar { Condvar(imp::Condvar::new()) } + + /// Prepares the condition variable for use. + /// + /// This should be called once the condition variable is at a stable memory + /// address. + #[inline] + pub unsafe fn init(&mut self) { self.0.init() } + + /// Signals one waiter on this condition variable to wake up. + #[inline] + pub unsafe fn notify_one(&self) { self.0.notify_one() } + + /// Awakens all current waiters on this condition variable. + #[inline] + pub unsafe fn notify_all(&self) { self.0.notify_all() } + + /// Waits for a signal on the specified mutex. + /// + /// Behavior is undefined if the mutex is not locked by the current thread. + /// Behavior is also undefined if more than one mutex is used concurrently + /// on this condition variable. + #[inline] + pub unsafe fn wait(&self, mutex: &Mutex) { self.0.wait(mutex::raw(mutex)) } + + /// Waits for a signal on the specified mutex with a timeout duration + /// specified by `dur` (a relative time into the future). + /// + /// Behavior is undefined if the mutex is not locked by the current thread. + /// Behavior is also undefined if more than one mutex is used concurrently + /// on this condition variable. + #[inline] + pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { + self.0.wait_timeout(mutex::raw(mutex), dur) + } + + /// Deallocates all resources associated with this condition variable. + /// + /// Behavior is undefined if there are current or will be future users of + /// this condition variable. + #[inline] + pub unsafe fn destroy(&self) { self.0.destroy() } +} diff --git a/ctr-std/src/sys_common/mod.rs b/ctr-std/src/sys_common/mod.rs index 7aedb69..936ff80 100644 --- a/ctr-std/src/sys_common/mod.rs +++ b/ctr-std/src/sys_common/mod.rs @@ -25,11 +25,16 @@ #![allow(missing_docs)] pub mod at_exit_imp; +pub mod condvar; pub mod io; pub mod mutex; pub mod poison; pub mod remutex; +pub mod rwlock; +pub mod thread; +pub mod thread_info; pub mod thread_local; +pub mod util; // common error constructors diff --git a/ctr-std/src/sys_common/rwlock.rs b/ctr-std/src/sys_common/rwlock.rs new file mode 100644 index 0000000..71a4f01 --- /dev/null +++ b/ctr-std/src/sys_common/rwlock.rs @@ -0,0 +1,82 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use sys::rwlock as imp; + +/// An OS-based reader-writer lock. +/// +/// This structure is entirely unsafe and serves as the lowest layer of a +/// cross-platform binding of system rwlocks. It is recommended to use the +/// safer types at the top level of this crate instead of this type. +pub struct RWLock(imp::RWLock); + +impl RWLock { + /// Creates a new reader-writer lock for use. + /// + /// Behavior is undefined if the reader-writer lock is moved after it is + /// first used with any of the functions below. + pub const fn new() -> RWLock { RWLock(imp::RWLock::new()) } + + /// Acquires shared access to the underlying lock, blocking the current + /// thread to do so. + /// + /// Behavior is undefined if the rwlock has been moved between this and any + /// previous method call. + #[inline] + pub unsafe fn read(&self) { self.0.read() } + + /// Attempts to acquire shared access to this lock, returning whether it + /// succeeded or not. + /// + /// This function does not block the current thread. + /// + /// Behavior is undefined if the rwlock has been moved between this and any + /// previous method call. + #[inline] + pub unsafe fn try_read(&self) -> bool { self.0.try_read() } + + /// Acquires write access to the underlying lock, blocking the current thread + /// to do so. + /// + /// Behavior is undefined if the rwlock has been moved between this and any + /// previous method call. + #[inline] + pub unsafe fn write(&self) { self.0.write() } + + /// Attempts to acquire exclusive access to this lock, returning whether it + /// succeeded or not. + /// + /// This function does not block the current thread. + /// + /// Behavior is undefined if the rwlock has been moved between this and any + /// previous method call. + #[inline] + pub unsafe fn try_write(&self) -> bool { self.0.try_write() } + + /// Unlocks previously acquired shared access to this lock. + /// + /// Behavior is undefined if the current thread does not have shared access. + #[inline] + pub unsafe fn read_unlock(&self) { self.0.read_unlock() } + + /// Unlocks previously acquired exclusive access to this lock. + /// + /// Behavior is undefined if the current thread does not currently have + /// exclusive access. + #[inline] + pub unsafe fn write_unlock(&self) { self.0.write_unlock() } + + /// Destroys OS-related resources with this RWLock. + /// + /// Behavior is undefined if there are any currently active users of this + /// lock. + #[inline] + pub unsafe fn destroy(&self) { self.0.destroy() } +} diff --git a/ctr-std/src/sys_common/thread.rs b/ctr-std/src/sys_common/thread.rs new file mode 100644 index 0000000..bb6baae --- /dev/null +++ b/ctr-std/src/sys_common/thread.rs @@ -0,0 +1,22 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use alloc::boxed::FnBox; +use libc; +//use sys::stack_overflow; + +pub unsafe fn start_thread(main: *mut libc::c_void) { + // Next, set up our stack overflow handler which may get triggered if we run + // out of stack. + // let _handler = stack_overflow::Handler::new(); + + // Finally, let's run some code. + Box::from_raw(main as *mut Box)() +} diff --git a/ctr-std/src/sys_common/thread_info.rs b/ctr-std/src/sys_common/thread_info.rs new file mode 100644 index 0000000..95d8b6c --- /dev/null +++ b/ctr-std/src/sys_common/thread_info.rs @@ -0,0 +1,61 @@ +// Copyright 2014 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![allow(dead_code)] // stack_guard isn't used right now on all platforms + +use cell::RefCell; +use thread::Thread; +use thread::LocalKeyState; + +struct ThreadInfo { + stack_guard: Option, + thread: Thread, +} + +thread_local! { static THREAD_INFO: RefCell> = RefCell::new(None) } + +impl ThreadInfo { + fn with(f: F) -> Option where F: FnOnce(&mut ThreadInfo) -> R { + if THREAD_INFO.state() == LocalKeyState::Destroyed { + return None + } + + THREAD_INFO.with(move |c| { + if c.borrow().is_none() { + *c.borrow_mut() = Some(ThreadInfo { + stack_guard: None, + thread: NewThread::new(None), + }) + } + Some(f(c.borrow_mut().as_mut().unwrap())) + }) + } +} + +pub fn current_thread() -> Option { + ThreadInfo::with(|info| info.thread.clone()) +} + +pub fn stack_guard() -> Option { + ThreadInfo::with(|info| info.stack_guard).and_then(|o| o) +} + +pub fn set(stack_guard: Option, thread: Thread) { + THREAD_INFO.with(|c| assert!(c.borrow().is_none())); + THREAD_INFO.with(move |c| *c.borrow_mut() = Some(ThreadInfo{ + stack_guard: stack_guard, + thread: thread, + })); +} + +// a hack to get around privacy restrictions; implemented by `std::thread` +pub trait NewThread { + fn new(name: Option) -> Self; +} diff --git a/ctr-std/src/sys_common/util.rs b/ctr-std/src/sys_common/util.rs new file mode 100644 index 0000000..aad0680 --- /dev/null +++ b/ctr-std/src/sys_common/util.rs @@ -0,0 +1,49 @@ +// Copyright 2013 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use fmt; +use io::prelude::*; +use sync::atomic::{self, Ordering}; +use sys::stdio::Stderr; + +pub fn min_stack() -> usize { + static MIN: atomic::AtomicUsize = atomic::AtomicUsize::new(0); + match MIN.load(Ordering::SeqCst) { + 0 => {} + n => return n - 1, + } + + // NOTE: We don't have env variable support on the 3DS so let's just use the + // default minimum + + // let amt = env::var("RUST_MIN_STACK").ok().and_then(|s| s.parse().ok()); + // let amt = amt.unwrap_or(2 * 1024 * 1024); + + let amt = 2 * 1024 * 1024; + + // 0 is our sentinel value, so ensure that we'll never see 0 after + // initialization has run + MIN.store(amt + 1, Ordering::SeqCst); + amt +} + +pub fn dumb_print(args: fmt::Arguments) { + let _ = Stderr::new().map(|mut stderr| stderr.write_fmt(args)); +} + +// Other platforms should use the appropriate platform-specific mechanism for +// aborting the process. If no platform-specific mechanism is available, +// ::intrinsics::abort() may be used instead. The above implementations cover +// all targets currently supported by libstd. + +pub fn abort(args: fmt::Arguments) -> ! { + dumb_print(format_args!("fatal runtime error: {}\n", args)); + unsafe { ::sys::abort_internal(); } +} diff --git a/ctr-std/src/thread/mod.rs b/ctr-std/src/thread/mod.rs index a8a6490..705efd4 100644 --- a/ctr-std/src/thread/mod.rs +++ b/ctr-std/src/thread/mod.rs @@ -170,6 +170,22 @@ #![stable(feature = "rust1", since = "1.0.0")] +use any::Any; +use cell::UnsafeCell; +use ffi::{CStr, CString}; +use fmt; +use io; +use panic; +//use panicking; +use str; +use sync::{Mutex, Condvar, Arc}; +use sys::thread as imp; +use sys_common::mutex; +use sys_common::thread_info; +use sys_common::util; +use sys_common::{AsInner, IntoInner}; +use time::Duration; + //////////////////////////////////////////////////////////////////////////////// // Thread-local storage //////////////////////////////////////////////////////////////////////////////// @@ -194,9 +210,1066 @@ pub use self::local::{LocalKey, LocalKeyState}; #[unstable(feature = "libstd_thread_internals", issue = "0")] #[doc(hidden)] pub use self::local::os::Key as __OsLocalKeyInner; -// We don't have stack unwinding, so this should always be false +//////////////////////////////////////////////////////////////////////////////// +// Builder +//////////////////////////////////////////////////////////////////////////////// + +/// Thread configuration. Provides detailed control over the properties +/// and behavior of new threads. +/// +/// # Examples +/// +/// ``` +/// use std::thread; +/// +/// let builder = thread::Builder::new(); +/// +/// let handler = builder.spawn(|| { +/// // thread code +/// }).unwrap(); +/// +/// handler.join().unwrap(); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +#[derive(Debug)] +pub struct Builder { + // A name for the thread-to-be, for identification in panic messages + name: Option, + // The size of the stack for the spawned thread in bytes + stack_size: Option, +} + +impl Builder { + /// Generates the base configuration for spawning a thread, from which + /// configuration methods can be chained. + /// + /// # Examples + /// + /// ``` + /// use std::thread; + /// + /// let builder = thread::Builder::new() + /// .name("foo".into()) + /// .stack_size(10); + /// + /// let handler = builder.spawn(|| { + /// // thread code + /// }).unwrap(); + /// + /// handler.join().unwrap(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn new() -> Builder { + Builder { + name: None, + stack_size: None, + } + } + + /// Names the thread-to-be. Currently the name is used for identification + /// only in panic messages. + /// + /// # Examples + /// + /// ``` + /// use std::thread; + /// + /// let builder = thread::Builder::new() + /// .name("foo".into()); + /// + /// let handler = builder.spawn(|| { + /// assert_eq!(thread::current().name(), Some("foo")) + /// }).unwrap(); + /// + /// handler.join().unwrap(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn name(mut self, name: String) -> Builder { + self.name = Some(name); + self + } + + /// Sets the size of the stack (in bytes) for the new thread. + /// + /// The actual stack size may be greater than this value if + /// the platform specifies minimal stack size. + /// + /// # Examples + /// + /// ``` + /// use std::thread; + /// + /// let builder = thread::Builder::new().stack_size(32 * 1024); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn stack_size(mut self, size: usize) -> Builder { + self.stack_size = Some(size); + self + } + + /// Spawns a new thread, and returns a join handle for it. + /// + /// The child thread may outlive the parent (unless the parent thread + /// is the main thread; the whole process is terminated when the main + /// thread finishes). The join handle can be used to block on + /// termination of the child thread, including recovering its panics. + /// + /// # Errors + /// + /// Unlike the [`spawn`] free function, this method yields an + /// [`io::Result`] to capture any failure to create the thread at + /// the OS level. + /// + /// [`spawn`]: ../../std/thread/fn.spawn.html + /// [`io::Result`]: ../../std/io/type.Result.html + /// + /// # Examples + /// + /// ``` + /// use std::thread; + /// + /// let builder = thread::Builder::new(); + /// + /// let handler = builder.spawn(|| { + /// // thread code + /// }).unwrap(); + /// + /// handler.join().unwrap(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn spawn(self, f: F) -> io::Result> where + F: FnOnce() -> T, F: Send + 'static, T: Send + 'static + { + let Builder { name, stack_size } = self; + + let stack_size = stack_size.unwrap_or(util::min_stack()); + + let my_thread = Thread::new(name); + let their_thread = my_thread.clone(); + + let my_packet : Arc>>> + = Arc::new(UnsafeCell::new(None)); + let their_packet = my_packet.clone(); + + let main = move || { + if let Some(name) = their_thread.cname() { + imp::Thread::set_name(name); + } + unsafe { + thread_info::set(imp::guard::current(), their_thread); + let try_result = panic::catch_unwind(panic::AssertUnwindSafe(f)); + *their_packet.get() = Some(try_result); + } + }; + + Ok(JoinHandle(JoinInner { + native: unsafe { + Some(imp::Thread::new(stack_size, Box::new(main))?) + }, + thread: my_thread, + packet: Packet(my_packet), + })) + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Free functions +//////////////////////////////////////////////////////////////////////////////// + +/// Spawns a new thread, returning a [`JoinHandle`] for it. +/// +/// The join handle will implicitly *detach* the child thread upon being +/// dropped. In this case, the child thread may outlive the parent (unless +/// the parent thread is the main thread; the whole process is terminated when +/// the main thread finishes). Additionally, the join handle provides a [`join`] +/// method that can be used to join the child thread. If the child thread +/// panics, [`join`] will return an [`Err`] containing the argument given to +/// [`panic`]. +/// +/// # Panics +/// +/// Panics if the OS fails to create a thread; use [`Builder::spawn`] +/// to recover from such errors. +/// +/// [`JoinHandle`]: ../../std/thread/struct.JoinHandle.html +/// [`join`]: ../../std/thread/struct.JoinHandle.html#method.join +/// [`Err`]: ../../std/result/enum.Result.html#variant.Err +/// [`panic`]: ../../std/macro.panic.html +/// [`Builder::spawn`]: ../../std/thread/struct.Builder.html#method.spawn +/// +/// # Examples +/// +/// ``` +/// use std::thread; +/// +/// let handler = thread::spawn(|| { +/// // thread code +/// }); +/// +/// handler.join().unwrap(); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn spawn(f: F) -> JoinHandle where + F: FnOnce() -> T, F: Send + 'static, T: Send + 'static +{ + Builder::new().spawn(f).unwrap() +} + +/// Gets a handle to the thread that invokes it. +/// +/// # Examples +/// +/// Getting a handle to the current thread with `thread::current()`: +/// +/// ``` +/// use std::thread; +/// +/// let handler = thread::Builder::new() +/// .name("named thread".into()) +/// .spawn(|| { +/// let handle = thread::current(); +/// assert_eq!(handle.name(), Some("named thread")); +/// }) +/// .unwrap(); +/// +/// handler.join().unwrap(); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn current() -> Thread { + thread_info::current_thread().expect("use of std::thread::current() is not \ + possible after the thread's local \ + data has been destroyed") +} + +/// Cooperatively gives up a timeslice to the OS scheduler. +/// +/// # Examples +/// +/// ``` +/// use std::thread; +/// +/// thread::yield_now(); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub fn yield_now() { + imp::Thread::yield_now() +} + +/// Determines whether the current thread is unwinding because of panic. +/// +/// # Examples +/// +/// ```should_panic +/// use std::thread; +/// +/// struct SomeStruct; +/// +/// impl Drop for SomeStruct { +/// fn drop(&mut self) { +/// if thread::panicking() { +/// println!("dropped while unwinding"); +/// } else { +/// println!("dropped while not unwinding"); +/// } +/// } +/// } +/// +/// { +/// print!("a: "); +/// let a = SomeStruct; +/// } +/// +/// { +/// print!("b: "); +/// let b = SomeStruct; +/// panic!() +/// } +/// ``` +// We don't have stack unwinding on the 3DS, so we can leave this as false for now #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub fn panicking() -> bool { - false + false +} + +/// Puts the current thread to sleep for the specified amount of time. +/// +/// The thread may sleep longer than the duration specified due to scheduling +/// specifics or platform-dependent functionality. +/// +/// # Platform behavior +/// +/// On Unix platforms this function will not return early due to a +/// signal being received or a spurious wakeup. +/// +/// # Examples +/// +/// ```no_run +/// use std::thread; +/// +/// // Let's sleep for 2 seconds: +/// thread::sleep_ms(2000); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +#[rustc_deprecated(since = "1.6.0", reason = "replaced by `std::thread::sleep`")] +pub fn sleep_ms(ms: u32) { + sleep(Duration::from_millis(ms as u64)) +} + +/// Puts the current thread to sleep for the specified amount of time. +/// +/// The thread may sleep longer than the duration specified due to scheduling +/// specifics or platform-dependent functionality. +/// +/// # Platform behavior +/// +/// On Unix platforms this function will not return early due to a +/// signal being received or a spurious wakeup. Platforms which do not support +/// nanosecond precision for sleeping will have `dur` rounded up to the nearest +/// granularity of time they can sleep for. +/// +/// # Examples +/// +/// ```no_run +/// use std::{thread, time}; +/// +/// let ten_millis = time::Duration::from_millis(10); +/// let now = time::Instant::now(); +/// +/// thread::sleep(ten_millis); +/// +/// assert!(now.elapsed() >= ten_millis); +/// ``` +#[stable(feature = "thread_sleep", since = "1.4.0")] +pub fn sleep(dur: Duration) { + imp::Thread::sleep(dur) +} + +/// Blocks unless or until the current thread's token is made available. +/// +/// Every thread is equipped with some basic low-level blocking support, via +/// the `park()` function and the [`unpark()`][unpark] method. These can be +/// used as a more CPU-efficient implementation of a spinlock. +/// +/// [unpark]: struct.Thread.html#method.unpark +/// +/// The API is typically used by acquiring a handle to the current thread, +/// placing that handle in a shared data structure so that other threads can +/// find it, and then parking (in a loop with a check for the token actually +/// being acquired). +/// +/// A call to `park` does not guarantee that the thread will remain parked +/// forever, and callers should be prepared for this possibility. +/// +/// See the [module documentation][thread] for more detail. +/// +/// [thread]: index.html +// +// The implementation currently uses the trivial strategy of a Mutex+Condvar +// with wakeup flag, which does not actually allow spurious wakeups. In the +// future, this will be implemented in a more efficient way, perhaps along the lines of +// http://cr.openjdk.java.net/~stefank/6989984.1/raw_files/new/src/os/linux/vm/os_linux.cpp +// or futuxes, and in either case may allow spurious wakeups. +#[stable(feature = "rust1", since = "1.0.0")] +pub fn park() { + let thread = current(); + let mut guard = thread.inner.lock.lock().unwrap(); + while !*guard { + guard = thread.inner.cvar.wait(guard).unwrap(); + } + *guard = false; +} + +/// Use [park_timeout]. +/// +/// Blocks unless or until the current thread's token is made available or +/// the specified duration has been reached (may wake spuriously). +/// +/// The semantics of this function are equivalent to `park()` except that the +/// thread will be blocked for roughly no longer than `ms`. This method +/// should not be used for precise timing due to anomalies such as +/// preemption or platform differences that may not cause the maximum +/// amount of time waited to be precisely `ms` long. +/// +/// See the [module documentation][thread] for more detail. +/// +/// [thread]: index.html +/// [park_timeout]: fn.park_timeout.html +#[stable(feature = "rust1", since = "1.0.0")] +#[rustc_deprecated(since = "1.6.0", reason = "replaced by `std::thread::park_timeout`")] +pub fn park_timeout_ms(ms: u32) { + park_timeout(Duration::from_millis(ms as u64)) +} + +/// Blocks unless or until the current thread's token is made available or +/// the specified duration has been reached (may wake spuriously). +/// +/// The semantics of this function are equivalent to `park()` except that the +/// thread will be blocked for roughly no longer than `dur`. This method +/// should not be used for precise timing due to anomalies such as +/// preemption or platform differences that may not cause the maximum +/// amount of time waited to be precisely `dur` long. +/// +/// See the module doc for more detail. +/// +/// # Platform behavior +/// +/// Platforms which do not support nanosecond precision for sleeping will have +/// `dur` rounded up to the nearest granularity of time they can sleep for. +/// +/// # Example +/// +/// Waiting for the complete expiration of the timeout: +/// +/// ```rust,no_run +/// use std::thread::park_timeout; +/// use std::time::{Instant, Duration}; +/// +/// let timeout = Duration::from_secs(2); +/// let beginning_park = Instant::now(); +/// park_timeout(timeout); +/// +/// while beginning_park.elapsed() < timeout { +/// println!("restarting park_timeout after {:?}", beginning_park.elapsed()); +/// let timeout = timeout - beginning_park.elapsed(); +/// park_timeout(timeout); +/// } +/// ``` +#[stable(feature = "park_timeout", since = "1.4.0")] +pub fn park_timeout(dur: Duration) { + let thread = current(); + let mut guard = thread.inner.lock.lock().unwrap(); + if !*guard { + let (g, _) = thread.inner.cvar.wait_timeout(guard, dur).unwrap(); + guard = g; + } + *guard = false; +} + +//////////////////////////////////////////////////////////////////////////////// +// ThreadId +//////////////////////////////////////////////////////////////////////////////// + +/// A unique identifier for a running thread. +/// +/// A `ThreadId` is an opaque object that has a unique value for each thread +/// that creates one. `ThreadId`s do not correspond to a thread's system- +/// designated identifier. +/// +/// # Examples +/// +/// ``` +/// #![feature(thread_id)] +/// +/// use std::thread; +/// +/// let handler = thread::Builder::new() +/// .spawn(|| { +/// let thread = thread::current(); +/// let thread_id = thread.id(); +/// }) +/// .unwrap(); +/// +/// handler.join().unwrap(); +/// ``` +#[unstable(feature = "thread_id", issue = "21507")] +#[derive(Eq, PartialEq, Copy, Clone)] +pub struct ThreadId(u64); + +impl ThreadId { + // Generate a new unique thread ID. + fn new() -> ThreadId { + static GUARD: mutex::Mutex = mutex::Mutex::new(); + static mut COUNTER: u64 = 0; + + unsafe { + GUARD.lock(); + + // If we somehow use up all our bits, panic so that we're not + // covering up subtle bugs of IDs being reused. + if COUNTER == ::u64::MAX { + GUARD.unlock(); + panic!("failed to generate unique thread ID: bitspace exhausted"); + } + + let id = COUNTER; + COUNTER += 1; + + GUARD.unlock(); + + ThreadId(id) + } + } +} + +#[unstable(feature = "thread_id", issue = "21507")] +impl fmt::Debug for ThreadId { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.pad("ThreadId { .. }") + } +} + +//////////////////////////////////////////////////////////////////////////////// +// Thread +//////////////////////////////////////////////////////////////////////////////// + +/// The internal representation of a `Thread` handle +struct Inner { + name: Option, // Guaranteed to be UTF-8 + id: ThreadId, + lock: Mutex, // true when there is a buffered unpark + cvar: Condvar, +} + +#[derive(Clone)] +#[stable(feature = "rust1", since = "1.0.0")] +/// A handle to a thread. +/// +/// # Examples +/// +/// ``` +/// use std::thread; +/// +/// let handler = thread::Builder::new() +/// .name("foo".into()) +/// .spawn(|| { +/// let thread = thread::current(); +/// println!("thread name: {}", thread.name().unwrap()); +/// }) +/// .unwrap(); +/// +/// handler.join().unwrap(); +/// ``` +pub struct Thread { + inner: Arc, +} + +impl Thread { + // Used only internally to construct a thread object without spawning + fn new(name: Option) -> Thread { + let cname = name.map(|n| { + CString::new(n).expect("thread name may not contain interior null bytes") + }); + Thread { + inner: Arc::new(Inner { + name: cname, + id: ThreadId::new(), + lock: Mutex::new(false), + cvar: Condvar::new(), + }) + } + } + + /// Atomically makes the handle's token available if it is not already. + /// + /// See the module doc for more detail. + /// + /// # Examples + /// + /// ``` + /// use std::thread; + /// + /// let handler = thread::Builder::new() + /// .spawn(|| { + /// let thread = thread::current(); + /// thread.unpark(); + /// }) + /// .unwrap(); + /// + /// handler.join().unwrap(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn unpark(&self) { + let mut guard = self.inner.lock.lock().unwrap(); + if !*guard { + *guard = true; + self.inner.cvar.notify_one(); + } + } + + /// Gets the thread's unique identifier. + /// + /// # Examples + /// + /// ``` + /// #![feature(thread_id)] + /// + /// use std::thread; + /// + /// let handler = thread::Builder::new() + /// .spawn(|| { + /// let thread = thread::current(); + /// println!("thread id: {:?}", thread.id()); + /// }) + /// .unwrap(); + /// + /// handler.join().unwrap(); + /// ``` + #[unstable(feature = "thread_id", issue = "21507")] + pub fn id(&self) -> ThreadId { + self.inner.id + } + + /// Gets the thread's name. + /// + /// # Examples + /// + /// Threads by default have no name specified: + /// + /// ``` + /// use std::thread; + /// + /// let builder = thread::Builder::new(); + /// + /// let handler = builder.spawn(|| { + /// assert!(thread::current().name().is_none()); + /// }).unwrap(); + /// + /// handler.join().unwrap(); + /// ``` + /// + /// Thread with a specified name: + /// + /// ``` + /// use std::thread; + /// + /// let builder = thread::Builder::new() + /// .name("foo".into()); + /// + /// let handler = builder.spawn(|| { + /// assert_eq!(thread::current().name(), Some("foo")) + /// }).unwrap(); + /// + /// handler.join().unwrap(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn name(&self) -> Option<&str> { + self.cname().map(|s| unsafe { str::from_utf8_unchecked(s.to_bytes()) } ) + } + + fn cname(&self) -> Option<&CStr> { + self.inner.name.as_ref().map(|s| &**s) + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl fmt::Debug for Thread { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + fmt::Debug::fmt(&self.name(), f) + } +} + +// a hack to get around privacy restrictions +impl thread_info::NewThread for Thread { + fn new(name: Option) -> Thread { Thread::new(name) } +} + +//////////////////////////////////////////////////////////////////////////////// +// JoinHandle +//////////////////////////////////////////////////////////////////////////////// + +/// Indicates the manner in which a thread exited. +/// +/// A thread that completes without panicking is considered to exit successfully. +#[stable(feature = "rust1", since = "1.0.0")] +pub type Result = ::result::Result>; + +// This packet is used to communicate the return value between the child thread +// and the parent thread. Memory is shared through the `Arc` within and there's +// no need for a mutex here because synchronization happens with `join()` (the +// parent thread never reads this packet until the child has exited). +// +// This packet itself is then stored into a `JoinInner` which in turns is placed +// in `JoinHandle` and `JoinGuard`. Due to the usage of `UnsafeCell` we need to +// manually worry about impls like Send and Sync. The type `T` should +// already always be Send (otherwise the thread could not have been created) and +// this type is inherently Sync because no methods take &self. Regardless, +// however, we add inheriting impls for Send/Sync to this type to ensure it's +// Send/Sync and that future modifications will still appropriately classify it. +struct Packet(Arc>>>); + +unsafe impl Send for Packet {} +unsafe impl Sync for Packet {} + +/// Inner representation for JoinHandle +struct JoinInner { + native: Option, + thread: Thread, + packet: Packet, +} + +impl JoinInner { + fn join(&mut self) -> Result { + self.native.take().unwrap().join(); + unsafe { + (*self.packet.0.get()).take().unwrap() + } + } +} + +/// An owned permission to join on a thread (block on its termination). +/// +/// A `JoinHandle` *detaches* the child thread when it is dropped. +/// +/// Due to platform restrictions, it is not possible to [`Clone`] this +/// handle: the ability to join a child thread is a uniquely-owned +/// permission. +/// +/// This `struct` is created by the [`thread::spawn`] function and the +/// [`thread::Builder::spawn`] method. +/// +/// # Examples +/// +/// Creation from [`thread::spawn`]: +/// +/// ``` +/// use std::thread; +/// +/// let join_handle: thread::JoinHandle<_> = thread::spawn(|| { +/// // some work here +/// }); +/// ``` +/// +/// Creation from [`thread::Builder::spawn`]: +/// +/// ``` +/// use std::thread; +/// +/// let builder = thread::Builder::new(); +/// +/// let join_handle: thread::JoinHandle<_> = builder.spawn(|| { +/// // some work here +/// }).unwrap(); +/// ``` +/// +/// [`Clone`]: ../../std/clone/trait.Clone.html +/// [`thread::spawn`]: fn.spawn.html +/// [`thread::Builder::spawn`]: struct.Builder.html#method.spawn +#[stable(feature = "rust1", since = "1.0.0")] +pub struct JoinHandle(JoinInner); + +impl JoinHandle { + /// Extracts a handle to the underlying thread. + /// + /// # Examples + /// + /// ``` + /// #![feature(thread_id)] + /// + /// use std::thread; + /// + /// let builder = thread::Builder::new(); + /// + /// let join_handle: thread::JoinHandle<_> = builder.spawn(|| { + /// // some work here + /// }).unwrap(); + /// + /// let thread = join_handle.thread(); + /// println!("thread id: {:?}", thread.id()); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn thread(&self) -> &Thread { + &self.0.thread + } + + /// Waits for the associated thread to finish. + /// + /// If the child thread panics, [`Err`] is returned with the parameter given + /// to [`panic`]. + /// + /// [`Err`]: ../../std/result/enum.Result.html#variant.Err + /// [`panic`]: ../../std/macro.panic.html + /// + /// # Examples + /// + /// ``` + /// use std::thread; + /// + /// let builder = thread::Builder::new(); + /// + /// let join_handle: thread::JoinHandle<_> = builder.spawn(|| { + /// // some work here + /// }).unwrap(); + /// join_handle.join().expect("Couldn't join on the associated thread"); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn join(mut self) -> Result { + self.0.join() + } +} + +impl AsInner for JoinHandle { + fn as_inner(&self) -> &imp::Thread { self.0.native.as_ref().unwrap() } +} + +impl IntoInner for JoinHandle { + fn into_inner(self) -> imp::Thread { self.0.native.unwrap() } +} + +#[stable(feature = "std_debug", since = "1.16.0")] +impl fmt::Debug for JoinHandle { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.pad("JoinHandle { .. }") + } +} + +fn _assert_sync_and_send() { + fn _assert_both() {} + _assert_both::>(); + _assert_both::(); +} + +//////////////////////////////////////////////////////////////////////////////// +// Tests +//////////////////////////////////////////////////////////////////////////////// + +#[cfg(all(test, not(target_os = "emscripten")))] +mod tests { + use any::Any; + use sync::mpsc::{channel, Sender}; + use result; + use super::{Builder}; + use thread; + use time::Duration; + use u32; + + // !!! These tests are dangerous. If something is buggy, they will hang, !!! + // !!! instead of exiting cleanly. This might wedge the buildbots. !!! + + #[test] + fn test_unnamed_thread() { + thread::spawn(move|| { + assert!(thread::current().name().is_none()); + }).join().ok().unwrap(); + } + + #[test] + fn test_named_thread() { + Builder::new().name("ada lovelace".to_string()).spawn(move|| { + assert!(thread::current().name().unwrap() == "ada lovelace".to_string()); + }).unwrap().join().unwrap(); + } + + #[test] + #[should_panic] + fn test_invalid_named_thread() { + let _ = Builder::new().name("ada l\0velace".to_string()).spawn(|| {}); + } + + #[test] + fn test_run_basic() { + let (tx, rx) = channel(); + thread::spawn(move|| { + tx.send(()).unwrap(); + }); + rx.recv().unwrap(); + } + + #[test] + fn test_join_panic() { + match thread::spawn(move|| { + panic!() + }).join() { + result::Result::Err(_) => (), + result::Result::Ok(()) => panic!() + } + } + + #[test] + fn test_spawn_sched() { + let (tx, rx) = channel(); + + fn f(i: i32, tx: Sender<()>) { + let tx = tx.clone(); + thread::spawn(move|| { + if i == 0 { + tx.send(()).unwrap(); + } else { + f(i - 1, tx); + } + }); + + } + f(10, tx); + rx.recv().unwrap(); + } + + #[test] + fn test_spawn_sched_childs_on_default_sched() { + let (tx, rx) = channel(); + + thread::spawn(move|| { + thread::spawn(move|| { + tx.send(()).unwrap(); + }); + }); + + rx.recv().unwrap(); + } + + fn avoid_copying_the_body(spawnfn: F) where F: FnOnce(Box) { + let (tx, rx) = channel(); + + let x: Box<_> = box 1; + let x_in_parent = (&*x) as *const i32 as usize; + + spawnfn(Box::new(move|| { + let x_in_child = (&*x) as *const i32 as usize; + tx.send(x_in_child).unwrap(); + })); + + let x_in_child = rx.recv().unwrap(); + assert_eq!(x_in_parent, x_in_child); + } + + #[test] + fn test_avoid_copying_the_body_spawn() { + avoid_copying_the_body(|v| { + thread::spawn(move || v()); + }); + } + + #[test] + fn test_avoid_copying_the_body_thread_spawn() { + avoid_copying_the_body(|f| { + thread::spawn(move|| { + f(); + }); + }) + } + + #[test] + fn test_avoid_copying_the_body_join() { + avoid_copying_the_body(|f| { + let _ = thread::spawn(move|| { + f() + }).join(); + }) + } + + #[test] + fn test_child_doesnt_ref_parent() { + // If the child refcounts the parent thread, this will stack overflow when + // climbing the thread tree to dereference each ancestor. (See #1789) + // (well, it would if the constant were 8000+ - I lowered it to be more + // valgrind-friendly. try this at home, instead..!) + const GENERATIONS: u32 = 16; + fn child_no(x: u32) -> Box { + return Box::new(move|| { + if x < GENERATIONS { + thread::spawn(move|| child_no(x+1)()); + } + }); + } + thread::spawn(|| child_no(0)()); + } + + #[test] + fn test_simple_newsched_spawn() { + thread::spawn(move || {}); + } + + #[test] + fn test_try_panic_message_static_str() { + match thread::spawn(move|| { + panic!("static string"); + }).join() { + Err(e) => { + type T = &'static str; + assert!(e.is::()); + assert_eq!(*e.downcast::().unwrap(), "static string"); + } + Ok(()) => panic!() + } + } + + #[test] + fn test_try_panic_message_owned_str() { + match thread::spawn(move|| { + panic!("owned string".to_string()); + }).join() { + Err(e) => { + type T = String; + assert!(e.is::()); + assert_eq!(*e.downcast::().unwrap(), "owned string".to_string()); + } + Ok(()) => panic!() + } + } + + #[test] + fn test_try_panic_message_any() { + match thread::spawn(move|| { + panic!(box 413u16 as Box); + }).join() { + Err(e) => { + type T = Box; + assert!(e.is::()); + let any = e.downcast::().unwrap(); + assert!(any.is::()); + assert_eq!(*any.downcast::().unwrap(), 413); + } + Ok(()) => panic!() + } + } + + #[test] + fn test_try_panic_message_unit_struct() { + struct Juju; + + match thread::spawn(move|| { + panic!(Juju) + }).join() { + Err(ref e) if e.is::() => {} + Err(_) | Ok(()) => panic!() + } + } + + #[test] + fn test_park_timeout_unpark_before() { + for _ in 0..10 { + thread::current().unpark(); + thread::park_timeout(Duration::from_millis(u32::MAX as u64)); + } + } + + #[test] + fn test_park_timeout_unpark_not_called() { + for _ in 0..10 { + thread::park_timeout(Duration::from_millis(10)); + } + } + + #[test] + fn test_park_timeout_unpark_called_other_thread() { + for _ in 0..10 { + let th = thread::current(); + + let _guard = thread::spawn(move || { + super::sleep(Duration::from_millis(50)); + th.unpark(); + }); + + thread::park_timeout(Duration::from_millis(u32::MAX as u64)); + } + } + + #[test] + fn sleep_ms_smoke() { + thread::sleep(Duration::from_millis(2)); + } + + #[test] + fn test_thread_id_equal() { + assert!(thread::current().id() == thread::current().id()); + } + + #[test] + fn test_thread_id_not_equal() { + let spawned_id = thread::spawn(|| thread::current().id()).join().unwrap(); + assert!(thread::current().id() != spawned_id); + } + + // NOTE: the corresponding test for stderr is in run-pass/thread-stderr, due + // to the test harness apparently interfering with stderr configuration. }