| use crate::cell::UnsafeCell; |
| use crate::sys::mutex::{self, Mutex}; |
| use crate::time::Duration; |
| |
| pub struct Condvar { |
| inner: UnsafeCell<libc::pthread_cond_t>, |
| } |
| |
| unsafe impl Send for Condvar {} |
| unsafe impl Sync for Condvar {} |
| |
| const TIMESPEC_MAX: libc::timespec = |
| libc::timespec { tv_sec: <libc::time_t>::MAX, tv_nsec: 1_000_000_000 - 1 }; |
| |
| fn saturating_cast_to_time_t(value: u64) -> libc::time_t { |
| if value > <libc::time_t>::MAX as u64 { <libc::time_t>::MAX } else { value as libc::time_t } |
| } |
| |
| impl Condvar { |
| pub const fn new() -> Condvar { |
| // Might be moved and address is changing it is better to avoid |
| // initialization of potentially opaque OS data before it landed |
| Condvar { inner: UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER) } |
| } |
| |
| pub unsafe fn init(&mut self) { |
| use crate::mem::MaybeUninit; |
| let mut attr = MaybeUninit::<libc::pthread_condattr_t>::uninit(); |
| let r = libc::pthread_condattr_init(attr.as_mut_ptr()); |
| assert_eq!(r, 0); |
| let r = libc::pthread_condattr_setclock(attr.as_mut_ptr(), libc::CLOCK_MONOTONIC); |
| assert_eq!(r, 0); |
| let r = libc::pthread_cond_init(self.inner.get(), attr.as_ptr()); |
| assert_eq!(r, 0); |
| let r = libc::pthread_condattr_destroy(attr.as_mut_ptr()); |
| assert_eq!(r, 0); |
| } |
| |
| #[inline] |
| pub unsafe fn notify_one(&self) { |
| let r = libc::pthread_cond_signal(self.inner.get()); |
| debug_assert_eq!(r, 0); |
| } |
| |
| #[inline] |
| pub unsafe fn notify_all(&self) { |
| let r = libc::pthread_cond_broadcast(self.inner.get()); |
| debug_assert_eq!(r, 0); |
| } |
| |
| #[inline] |
| pub unsafe fn wait(&self, mutex: &Mutex) { |
| let r = libc::pthread_cond_wait(self.inner.get(), mutex::raw(mutex)); |
| debug_assert_eq!(r, 0); |
| } |
| |
| // This implementation is used on systems that support pthread_condattr_setclock |
| // where we configure condition variable to use monotonic clock (instead of |
| // default system clock). This approach avoids all problems that result |
| // from changes made to the system time. |
| pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { |
| use crate::mem; |
| |
| 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 r = libc::pthread_cond_timedwait(self.inner.get(), mutex::raw(mutex), &timeout); |
| assert!(r == libc::ETIMEDOUT || r == 0); |
| r == 0 |
| } |
| |
| #[inline] |
| pub unsafe fn destroy(&self) { |
| let r = libc::pthread_cond_destroy(self.inner.get()); |
| debug_assert_eq!(r, 0); |
| } |
| } |