8ec47261e1
Configure condition variables to use monotonic time using pthread_condattr_setclock on systems where this is possible. This fixes the issue when thread waiting on condition variable is woken up too late when system time is moved backwards.
71 lines
2.7 KiB
Rust
71 lines
2.7 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use time::Duration;
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use sys_common::mutex::{self, Mutex};
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use sys::condvar as imp;
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/// An OS-based condition variable.
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///
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/// This structure is the lowest layer possible on top of the OS-provided
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/// condition variables. It is consequently entirely unsafe to use. It is
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/// recommended to use the safer types at the top level of this crate instead of
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/// this type.
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pub struct Condvar(imp::Condvar);
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impl Condvar {
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/// Creates a new condition variable for use.
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///
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/// Behavior is undefined if the condition variable is moved after it is
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/// first used with any of the functions below.
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pub const fn new() -> Condvar { Condvar(imp::Condvar::new()) }
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/// Prepares the condition variable for use.
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///
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/// This should be called once the condition variable is at a stable memory
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/// address.
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#[inline]
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pub unsafe fn init(&mut self) { self.0.init() }
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/// Signals one waiter on this condition variable to wake up.
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#[inline]
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pub unsafe fn notify_one(&self) { self.0.notify_one() }
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/// Awakens all current waiters on this condition variable.
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#[inline]
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pub unsafe fn notify_all(&self) { self.0.notify_all() }
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/// Waits for a signal on the specified mutex.
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///
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/// Behavior is undefined if the mutex is not locked by the current thread.
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/// Behavior is also undefined if more than one mutex is used concurrently
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/// on this condition variable.
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#[inline]
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pub unsafe fn wait(&self, mutex: &Mutex) { self.0.wait(mutex::raw(mutex)) }
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/// Waits for a signal on the specified mutex with a timeout duration
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/// specified by `dur` (a relative time into the future).
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///
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/// Behavior is undefined if the mutex is not locked by the current thread.
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/// Behavior is also undefined if more than one mutex is used concurrently
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/// on this condition variable.
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#[inline]
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pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool {
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self.0.wait_timeout(mutex::raw(mutex), dur)
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}
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/// Deallocates all resources associated with this condition variable.
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///
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/// Behavior is undefined if there are current or will be future users of
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/// this condition variable.
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#[inline]
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pub unsafe fn destroy(&self) { self.0.destroy() }
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}
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