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| 1 | +use crate::cell::UnsafeCell; |
| 2 | +use crate::ptr; |
| 3 | +use crate::sync::atomic::{AtomicPtr, Ordering::Relaxed}; |
| 4 | +use crate::sys::locks::mutex::{self, Mutex}; |
| 5 | +use crate::sys::time::TIMESPEC_MAX; |
| 6 | +use crate::sys_common::lazy_box::{LazyBox, LazyInit}; |
| 7 | +use crate::time::Duration; |
| 8 | + |
| 9 | +extern "C" { |
| 10 | + pub fn pthread_cond_timedwait( |
| 11 | + cond: *mut libc::pthread_cond_t, |
| 12 | + lock: *mut libc::pthread_mutex_t, |
| 13 | + adstime: *const libc::timespec, |
| 14 | + ) -> libc::c_int; |
| 15 | +} |
| 16 | + |
| 17 | +struct AllocatedCondvar(UnsafeCell<libc::pthread_cond_t>); |
| 18 | + |
| 19 | +pub struct Condvar { |
| 20 | + inner: LazyBox<AllocatedCondvar>, |
| 21 | + mutex: AtomicPtr<libc::pthread_mutex_t>, |
| 22 | +} |
| 23 | + |
| 24 | +#[inline] |
| 25 | +fn raw(c: &Condvar) -> *mut libc::pthread_cond_t { |
| 26 | + c.inner.0.get() |
| 27 | +} |
| 28 | + |
| 29 | +unsafe impl Send for AllocatedCondvar {} |
| 30 | +unsafe impl Sync for AllocatedCondvar {} |
| 31 | + |
| 32 | +impl LazyInit for AllocatedCondvar { |
| 33 | + fn init() -> Box<Self> { |
| 34 | + let condvar = Box::new(AllocatedCondvar(UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER))); |
| 35 | + |
| 36 | + let r = unsafe { libc::pthread_cond_init(condvar.0.get(), crate::ptr::null()) }; |
| 37 | + assert_eq!(r, 0); |
| 38 | + |
| 39 | + condvar |
| 40 | + } |
| 41 | +} |
| 42 | + |
| 43 | +impl Drop for AllocatedCondvar { |
| 44 | + #[inline] |
| 45 | + fn drop(&mut self) { |
| 46 | + let r = unsafe { libc::pthread_cond_destroy(self.0.get()) }; |
| 47 | + debug_assert_eq!(r, 0); |
| 48 | + } |
| 49 | +} |
| 50 | + |
| 51 | +impl Condvar { |
| 52 | + pub const fn new() -> Condvar { |
| 53 | + Condvar { inner: LazyBox::new(), mutex: AtomicPtr::new(ptr::null_mut()) } |
| 54 | + } |
| 55 | + |
| 56 | + #[inline] |
| 57 | + fn verify(&self, mutex: *mut libc::pthread_mutex_t) { |
| 58 | + match self.mutex.compare_exchange(ptr::null_mut(), mutex, Relaxed, Relaxed) { |
| 59 | + Ok(_) => {} // Stored the address |
| 60 | + Err(n) if n == mutex => {} // Lost a race to store the same address |
| 61 | + _ => panic!("attempted to use a condition variable with two mutexes"), |
| 62 | + } |
| 63 | + } |
| 64 | + |
| 65 | + #[inline] |
| 66 | + pub fn notify_one(&self) { |
| 67 | + let r = unsafe { libc::pthread_cond_signal(raw(self)) }; |
| 68 | + debug_assert_eq!(r, 0); |
| 69 | + } |
| 70 | + |
| 71 | + #[inline] |
| 72 | + pub fn notify_all(&self) { |
| 73 | + let r = unsafe { libc::pthread_cond_broadcast(raw(self)) }; |
| 74 | + debug_assert_eq!(r, 0); |
| 75 | + } |
| 76 | + |
| 77 | + #[inline] |
| 78 | + pub unsafe fn wait(&self, mutex: &Mutex) { |
| 79 | + let mutex = mutex::raw(mutex); |
| 80 | + self.verify(mutex); |
| 81 | + let r = libc::pthread_cond_wait(raw(self), mutex); |
| 82 | + debug_assert_eq!(r, 0); |
| 83 | + } |
| 84 | + |
| 85 | + pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { |
| 86 | + use crate::sys::time::Timespec; |
| 87 | + |
| 88 | + let mutex = mutex::raw(mutex); |
| 89 | + self.verify(mutex); |
| 90 | + |
| 91 | + let timeout = Timespec::now(libc::CLOCK_MONOTONIC) |
| 92 | + .checked_add_duration(&dur) |
| 93 | + .and_then(|t| t.to_timespec()) |
| 94 | + .unwrap_or(TIMESPEC_MAX); |
| 95 | + |
| 96 | + let r = pthread_cond_timedwait(raw(self), mutex, &timeout); |
| 97 | + assert!(r == libc::ETIMEDOUT || r == 0); |
| 98 | + r == 0 |
| 99 | + } |
| 100 | +} |
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