X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=library%2Fstd%2Fsrc%2Fsys%2Funix%2Flocks%2Fpthread_condvar.rs;h=6be1abc2b080a0164d772b5f6eed32b7f2bc9b9d;hb=cb4753135e69f6d718a11a72f429acc3f074d51d;hp=1ddb09905db2cfa0f3002535eb8729c3400310b9;hpb=55ae6516f9bed7a1cd65b784c56919133486f546;p=rust.git diff --git a/library/std/src/sys/unix/locks/pthread_condvar.rs b/library/std/src/sys/unix/locks/pthread_condvar.rs index 1ddb09905db..6be1abc2b08 100644 --- a/library/std/src/sys/unix/locks/pthread_condvar.rs +++ b/library/std/src/sys/unix/locks/pthread_condvar.rs @@ -2,6 +2,7 @@ use crate::ptr; use crate::sync::atomic::{AtomicPtr, Ordering::Relaxed}; use crate::sys::locks::{pthread_mutex, Mutex}; +use crate::sys::time::TIMESPEC_MAX; use crate::sys_common::lazy_box::{LazyBox, LazyInit}; use crate::time::Duration; @@ -12,13 +13,6 @@ pub struct Condvar { mutex: AtomicPtr, } -const TIMESPEC_MAX: libc::timespec = - libc::timespec { tv_sec: ::MAX, tv_nsec: 1_000_000_000 - 1 }; - -fn saturating_cast_to_time_t(value: u64) -> libc::time_t { - if value > ::MAX as u64 { ::MAX } else { value as libc::time_t } -} - #[inline] fn raw(c: &Condvar) -> *mut libc::pthread_cond_t { c.inner.0.get() @@ -133,26 +127,15 @@ pub unsafe fn wait(&self, mutex: &Mutex) { target_os = "horizon" )))] pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { - use crate::mem; + use crate::sys::time::Timespec; let mutex = pthread_mutex::raw(mutex); self.verify(mutex); - let mut now: libc::timespec = mem::zeroed(); - let r = libc::clock_gettime(libc::CLOCK_MONOTONIC, &mut now); - assert_eq!(r, 0); - - // Nanosecond calculations can't overflow because both values are below 1e9. - let nsec = dur.subsec_nanos() + now.tv_nsec as u32; - - let sec = saturating_cast_to_time_t(dur.as_secs()) - .checked_add((nsec / 1_000_000_000) as libc::time_t) - .and_then(|s| s.checked_add(now.tv_sec)); - let nsec = nsec % 1_000_000_000; - - let timeout = - sec.map(|s| libc::timespec { tv_sec: s, tv_nsec: nsec as _ }).unwrap_or(TIMESPEC_MAX); - + let timeout = Timespec::now(libc::CLOCK_MONOTONIC) + .checked_add_duration(&dur) + .and_then(|t| t.to_timespec()) + .unwrap_or(TIMESPEC_MAX); let r = libc::pthread_cond_timedwait(raw(self), mutex, &timeout); assert!(r == libc::ETIMEDOUT || r == 0); r == 0 @@ -169,57 +152,41 @@ pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { target_os = "espidf", target_os = "horizon" ))] - pub unsafe fn wait_timeout(&self, mutex: &Mutex, mut dur: Duration) -> bool { + pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { + use crate::sys::time::SystemTime; use crate::time::Instant; let mutex = pthread_mutex::raw(mutex); self.verify(mutex); - // 1000 years - let max_dur = Duration::from_secs(1000 * 365 * 86400); - - if dur > max_dur { - // OSX implementation of `pthread_cond_timedwait` is buggy - // with super long durations. When duration is greater than - // 0x100_0000_0000_0000 seconds, `pthread_cond_timedwait` - // in macOS Sierra return error 316. - // - // This program demonstrates the issue: - // https://gist.github.com/stepancheg/198db4623a20aad2ad7cddb8fda4a63c - // - // To work around this issue, and possible bugs of other OSes, timeout - // is clamped to 1000 years, which is allowable per the API of `wait_timeout` - // because of spurious wakeups. - - dur = max_dur; - } - - // First, figure out what time it currently is, in both system and - // stable time. pthread_cond_timedwait uses system time, but we want to - // report timeout based on stable time. - let mut sys_now = libc::timeval { tv_sec: 0, tv_usec: 0 }; - let stable_now = Instant::now(); - let r = libc::gettimeofday(&mut sys_now, ptr::null_mut()); - assert_eq!(r, 0, "unexpected error: {:?}", crate::io::Error::last_os_error()); - - let nsec = dur.subsec_nanos() as libc::c_long + (sys_now.tv_usec * 1000) as libc::c_long; - let extra = (nsec / 1_000_000_000) as libc::time_t; - let nsec = nsec % 1_000_000_000; - let seconds = saturating_cast_to_time_t(dur.as_secs()); - - let timeout = sys_now - .tv_sec - .checked_add(extra) - .and_then(|s| s.checked_add(seconds)) - .map(|s| libc::timespec { tv_sec: s, tv_nsec: nsec }) + // OSX implementation of `pthread_cond_timedwait` is buggy + // with super long durations. When duration is greater than + // 0x100_0000_0000_0000 seconds, `pthread_cond_timedwait` + // in macOS Sierra returns error 316. + // + // This program demonstrates the issue: + // https://gist.github.com/stepancheg/198db4623a20aad2ad7cddb8fda4a63c + // + // To work around this issue, and possible bugs of other OSes, timeout + // is clamped to 1000 years, which is allowable per the API of `wait_timeout` + // because of spurious wakeups. + let dur = Duration::min(dur, Duration::from_secs(1000 * 365 * 86400)); + + // pthread_cond_timedwait uses system time, but we want to report timeout + // based on stable time. + let now = Instant::now(); + + let timeout = SystemTime::now() + .t + .checked_add_duration(&dur) + .and_then(|t| t.to_timespec()) .unwrap_or(TIMESPEC_MAX); - // And wait! let r = libc::pthread_cond_timedwait(raw(self), mutex, &timeout); debug_assert!(r == libc::ETIMEDOUT || r == 0); // ETIMEDOUT is not a totally reliable method of determining timeout due // to clock shifts, so do the check ourselves - stable_now.elapsed() < dur + now.elapsed() < dur } }