1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
14 use sys::mutex::{self, Mutex};
15 use time::{Instant, Duration};
17 pub struct Condvar { inner: UnsafeCell<libc::pthread_cond_t> }
19 unsafe impl Send for Condvar {}
20 unsafe impl Sync for Condvar {}
23 pub const fn new() -> Condvar {
24 // Might be moved and address is changing it is better to avoid
25 // initialization of potentially opaque OS data before it landed
26 Condvar { inner: UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER) }
30 pub unsafe fn notify_one(&self) {
31 let r = libc::pthread_cond_signal(self.inner.get());
32 debug_assert_eq!(r, 0);
36 pub unsafe fn notify_all(&self) {
37 let r = libc::pthread_cond_broadcast(self.inner.get());
38 debug_assert_eq!(r, 0);
42 pub unsafe fn wait(&self, mutex: &Mutex) {
43 let r = libc::pthread_cond_wait(self.inner.get(), mutex::raw(mutex));
44 debug_assert_eq!(r, 0);
47 // This implementation is modeled after libcxx's condition_variable
48 // https://github.com/llvm-mirror/libcxx/blob/release_35/src/condition_variable.cpp#L46
49 // https://github.com/llvm-mirror/libcxx/blob/release_35/include/__mutex_base#L367
50 pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool {
51 // First, figure out what time it currently is, in both system and
52 // stable time. pthread_cond_timedwait uses system time, but we want to
53 // report timeout based on stable time.
54 let mut sys_now = libc::timeval { tv_sec: 0, tv_usec: 0 };
55 let stable_now = Instant::now();
56 let r = libc::gettimeofday(&mut sys_now, ptr::null_mut());
57 debug_assert_eq!(r, 0);
59 let nsec = dur.subsec_nanos() as libc::c_long +
60 (sys_now.tv_usec * 1000) as libc::c_long;
61 let extra = (nsec / 1_000_000_000) as libc::time_t;
62 let nsec = nsec % 1_000_000_000;
63 let seconds = dur.as_secs() as libc::time_t;
65 let timeout = sys_now.tv_sec.checked_add(extra).and_then(|s| {
66 s.checked_add(seconds)
68 libc::timespec { tv_sec: s, tv_nsec: nsec }
69 }).unwrap_or_else(|| {
71 tv_sec: <libc::time_t>::max_value(),
72 tv_nsec: 1_000_000_000 - 1,
77 let r = libc::pthread_cond_timedwait(self.inner.get(), mutex::raw(mutex),
79 debug_assert!(r == libc::ETIMEDOUT || r == 0);
81 // ETIMEDOUT is not a totally reliable method of determining timeout due
82 // to clock shifts, so do the check ourselves
83 stable_now.elapsed() < dur
87 #[cfg(not(target_os = "dragonfly"))]
88 pub unsafe fn destroy(&self) {
89 let r = libc::pthread_cond_destroy(self.inner.get());
90 debug_assert_eq!(r, 0);
94 #[cfg(target_os = "dragonfly")]
95 pub unsafe fn destroy(&self) {
96 let r = libc::pthread_cond_destroy(self.inner.get());
97 // On DragonFly pthread_cond_destroy() returns EINVAL if called on
98 // a condvar that was just initialized with
99 // libc::PTHREAD_COND_INITIALIZER. Once it is used or
100 // pthread_cond_init() is called, this behaviour no longer occurs.
101 debug_assert!(r == 0 || r == libc::EINVAL);