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Rewrite Condvar::wait_timeout and make it public

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**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.
This commit is contained in:
Steven Fackler 2015-01-13 21:24:26 -08:00
parent 3d5fbae338
commit 08f6380a9f
8 changed files with 343 additions and 97 deletions
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68
src/libstd/time/mod.rs
View file

@ -10,7 +10,7 @@
//! Temporal quantification.
use libc;
use sys::time::SteadyTime;
pub use self::duration::Duration;
@ -20,69 +20,5 @@ pub mod duration;
/// in nanoseconds since an unspecified epoch.
// NB: this is intentionally not public, this is not ready to stabilize its api.
fn precise_time_ns() -> u64 {
return os_precise_time_ns();
#[cfg(windows)]
fn os_precise_time_ns() -> u64 {
let mut ticks_per_s = 0;
assert_eq!(unsafe {
libc::QueryPerformanceFrequency(&mut ticks_per_s)
}, 1);
let ticks_per_s = if ticks_per_s == 0 {1} else {ticks_per_s};
let mut ticks = 0;
assert_eq!(unsafe {
libc::QueryPerformanceCounter(&mut ticks)
}, 1);
return (ticks as u64 * 1000000000) / (ticks_per_s as u64);
}
#[cfg(any(target_os = "macos", target_os = "ios"))]
fn os_precise_time_ns() -> u64 {
use sync;
static mut TIMEBASE: libc::mach_timebase_info = libc::mach_timebase_info { numer: 0,
denom: 0 };
static ONCE: sync::Once = sync::ONCE_INIT;
unsafe {
ONCE.call_once(|| {
imp::mach_timebase_info(&mut TIMEBASE);
});
let time = imp::mach_absolute_time();
time * TIMEBASE.numer as u64 / TIMEBASE.denom as u64
}
}
#[cfg(not(any(windows, target_os = "macos", target_os = "ios")))]
fn os_precise_time_ns() -> u64 {
let mut ts = libc::timespec { tv_sec: 0, tv_nsec: 0 };
unsafe {
imp::clock_gettime(libc::CLOCK_MONOTONIC, &mut ts);
}
return (ts.tv_sec as u64) * 1000000000 + (ts.tv_nsec as u64)
}
}
#[cfg(all(unix, not(target_os = "macos"), not(target_os = "ios")))]
mod imp {
use libc::{c_int, timespec};
// Apparently android provides this in some other library?
#[cfg(not(target_os = "android"))]
#[link(name = "rt")]
extern {}
extern {
pub fn clock_gettime(clk_id: c_int, tp: *mut timespec) -> c_int;
}
}
#[cfg(any(target_os = "macos", target_os = "ios"))]
mod imp {
use libc::{c_int, mach_timebase_info};
extern {
pub fn mach_absolute_time() -> u64;
pub fn mach_timebase_info(info: *mut mach_timebase_info) -> c_int;
}
SteadyTime::now().ns()
}