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Steven Fackler
08f6380a9f
**The implementation is a direct adaptation of libcxx's condition_variable implementation.** pthread_cond_timedwait uses the non-monotonic system clock. It's possible to change the clock to a monotonic via pthread_cond_attr, but this is incompatible with static initialization. To deal with this, we calculate the timeout using the system clock, and maintain a separate record of the start and end times with a monotonic clock to be used for calculation of the return value.
51 lines
1.3 KiB
Rust
51 lines
1.3 KiB
Rust
// Copyright 2015 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 libc;
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use ops::Sub;
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use time::Duration;
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use sync::{Once, ONCE_INIT};
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pub struct SteadyTime {
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t: libc::LARGE_INTEGER,
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}
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impl SteadyTime {
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pub fn now() -> SteadyTime {
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let mut t = SteadyTime { t: 0 };
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unsafe { libc::QueryPerformanceCounter(&mut t.t); }
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t
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}
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pub fn ns(&self) -> u64 {
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self.t as u64 * 1_000_000_000 / frequency() as u64
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}
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}
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fn frequency() -> libc::LARGE_INTEGER {
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static mut FREQUENCY: libc::LARGE_INTEGER = 0;
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static ONCE: Once = ONCE_INIT;
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unsafe {
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ONCE.call_once(|| {
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libc::QueryPerformanceFrequency(&mut FREQUENCY);
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});
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FREQUENCY
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}
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}
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impl<'a> Sub for &'a SteadyTime {
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type Output = Duration;
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fn sub(self, other: &SteadyTime) -> Duration {
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let diff = self.t as i64 - other.t as i64;
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Duration::microseconds(diff * 1_000_000 / frequency() as i64)
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}
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}
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