| use crate::cell::UnsafeCell; |
| use crate::ptr; |
| use crate::sync::atomic::{AtomicPtr, Ordering::Relaxed}; |
| use crate::sys::locks::{pthread_mutex, Mutex}; |
| #[cfg(not(target_os = "nto"))] |
| use crate::sys::time::TIMESPEC_MAX; |
| #[cfg(target_os = "nto")] |
| use crate::sys::time::TIMESPEC_MAX_CAPPED; |
| use crate::sys_common::lazy_box::{LazyBox, LazyInit}; |
| use crate::time::Duration; |
| |
| struct AllocatedCondvar(UnsafeCell<libc::pthread_cond_t>); |
| |
| pub struct Condvar { |
| inner: LazyBox<AllocatedCondvar>, |
| mutex: AtomicPtr<libc::pthread_mutex_t>, |
| } |
| |
| #[inline] |
| fn raw(c: &Condvar) -> *mut libc::pthread_cond_t { |
| c.inner.0.get() |
| } |
| |
| unsafe impl Send for AllocatedCondvar {} |
| unsafe impl Sync for AllocatedCondvar {} |
| |
| impl LazyInit for AllocatedCondvar { |
| fn init() -> Box<Self> { |
| let condvar = Box::new(AllocatedCondvar(UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER))); |
| |
| cfg_if::cfg_if! { |
| if #[cfg(any( |
| target_os = "macos", |
| target_os = "ios", |
| target_os = "tvos", |
| target_os = "watchos", |
| target_os = "l4re", |
| target_os = "android", |
| target_os = "redox" |
| ))] { |
| // `pthread_condattr_setclock` is unfortunately not supported on these platforms. |
| } else if #[cfg(any(target_os = "espidf", target_os = "horizon"))] { |
| // NOTE: ESP-IDF's PTHREAD_COND_INITIALIZER support is not released yet |
| // So on that platform, init() should always be called |
| // Moreover, that platform does not have pthread_condattr_setclock support, |
| // hence that initialization should be skipped as well |
| // |
| // Similar story for the 3DS (horizon). |
| let r = unsafe { libc::pthread_cond_init(condvar.0.get(), crate::ptr::null()) }; |
| assert_eq!(r, 0); |
| } else { |
| use crate::mem::MaybeUninit; |
| let mut attr = MaybeUninit::<libc::pthread_condattr_t>::uninit(); |
| let r = unsafe { libc::pthread_condattr_init(attr.as_mut_ptr()) }; |
| assert_eq!(r, 0); |
| let r = unsafe { libc::pthread_condattr_setclock(attr.as_mut_ptr(), libc::CLOCK_MONOTONIC) }; |
| assert_eq!(r, 0); |
| let r = unsafe { libc::pthread_cond_init(condvar.0.get(), attr.as_ptr()) }; |
| assert_eq!(r, 0); |
| let r = unsafe { libc::pthread_condattr_destroy(attr.as_mut_ptr()) }; |
| assert_eq!(r, 0); |
| } |
| } |
| |
| condvar |
| } |
| } |
| |
| impl Drop for AllocatedCondvar { |
| #[inline] |
| fn drop(&mut self) { |
| let r = unsafe { libc::pthread_cond_destroy(self.0.get()) }; |
| if cfg!(target_os = "dragonfly") { |
| // On DragonFly pthread_cond_destroy() returns EINVAL if called on |
| // a condvar that was just initialized with |
| // libc::PTHREAD_COND_INITIALIZER. Once it is used or |
| // pthread_cond_init() is called, this behaviour no longer occurs. |
| debug_assert!(r == 0 || r == libc::EINVAL); |
| } else { |
| debug_assert_eq!(r, 0); |
| } |
| } |
| } |
| |
| impl Condvar { |
| pub const fn new() -> Condvar { |
| Condvar { inner: LazyBox::new(), mutex: AtomicPtr::new(ptr::null_mut()) } |
| } |
| |
| #[inline] |
| fn verify(&self, mutex: *mut libc::pthread_mutex_t) { |
| // Relaxed is okay here because we never read through `self.addr`, and only use it to |
| // compare addresses. |
| match self.mutex.compare_exchange(ptr::null_mut(), mutex, Relaxed, Relaxed) { |
| Ok(_) => {} // Stored the address |
| Err(n) if n == mutex => {} // Lost a race to store the same address |
| _ => panic!("attempted to use a condition variable with two mutexes"), |
| } |
| } |
| |
| #[inline] |
| pub fn notify_one(&self) { |
| let r = unsafe { libc::pthread_cond_signal(raw(self)) }; |
| debug_assert_eq!(r, 0); |
| } |
| |
| #[inline] |
| pub fn notify_all(&self) { |
| let r = unsafe { libc::pthread_cond_broadcast(raw(self)) }; |
| debug_assert_eq!(r, 0); |
| } |
| |
| #[inline] |
| pub unsafe fn wait(&self, mutex: &Mutex) { |
| let mutex = pthread_mutex::raw(mutex); |
| self.verify(mutex); |
| let r = libc::pthread_cond_wait(raw(self), 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. |
| #[cfg(not(any( |
| target_os = "macos", |
| target_os = "ios", |
| target_os = "tvos", |
| target_os = "watchos", |
| target_os = "android", |
| target_os = "espidf", |
| target_os = "horizon" |
| )))] |
| pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { |
| use crate::sys::time::Timespec; |
| |
| let mutex = pthread_mutex::raw(mutex); |
| self.verify(mutex); |
| |
| #[cfg(not(target_os = "nto"))] |
| let timeout = Timespec::now(libc::CLOCK_MONOTONIC) |
| .checked_add_duration(&dur) |
| .and_then(|t| t.to_timespec()) |
| .unwrap_or(TIMESPEC_MAX); |
| |
| #[cfg(target_os = "nto")] |
| let timeout = Timespec::now(libc::CLOCK_MONOTONIC) |
| .checked_add_duration(&dur) |
| .and_then(|t| t.to_timespec_capped()) |
| .unwrap_or(TIMESPEC_MAX_CAPPED); |
| |
| let r = libc::pthread_cond_timedwait(raw(self), mutex, &timeout); |
| assert!(r == libc::ETIMEDOUT || r == 0); |
| r == 0 |
| } |
| |
| // This implementation is modeled after libcxx's condition_variable |
| // https://github.com/llvm-mirror/libcxx/blob/release_35/src/condition_variable.cpp#L46 |
| // https://github.com/llvm-mirror/libcxx/blob/release_35/include/__mutex_base#L367 |
| #[cfg(any( |
| target_os = "macos", |
| target_os = "ios", |
| target_os = "tvos", |
| target_os = "watchos", |
| target_os = "android", |
| target_os = "espidf", |
| target_os = "horizon" |
| ))] |
| 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); |
| |
| // 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); |
| |
| 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 |
| now.elapsed() < dur |
| } |
| } |