1 files changed, 172 insertions, 0 deletions
diff --git a/library/std/src/sys/pal/unix/sync/condvar.rs b/library/std/src/sys/pal/unix/sync/condvar.rs
new file mode 100644
index 00000000000..13eeba9c880
--- /dev/null
+++ b/library/std/src/sys/pal/unix/sync/condvar.rs
@@ -0,0 +1,172 @@
+use super::Mutex;
+use crate::cell::UnsafeCell;
+use crate::pin::Pin;
+#[cfg(not(target_os = "nto"))]
+use crate::sys::pal::time::TIMESPEC_MAX;
+#[cfg(target_os = "nto")]
+use crate::sys::pal::time::TIMESPEC_MAX_CAPPED;
+use crate::sys::pal::time::Timespec;
+use crate::time::Duration;
+
+pub struct Condvar {
+    inner: UnsafeCell<libc::pthread_cond_t>,
+}
+
+impl Condvar {
+    pub fn new() -> Condvar {
+        Condvar { inner: UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER) }
+    }
+
+    #[inline]
+    fn raw(&self) -> *mut libc::pthread_cond_t {
+        self.inner.get()
+    }
+
+    /// # Safety
+    /// `init` must have been called.
+    #[inline]
+    pub unsafe fn notify_one(self: Pin<&Self>) {
+        let r = unsafe { libc::pthread_cond_signal(self.raw()) };
+        debug_assert_eq!(r, 0);
+    }
+
+    /// # Safety
+    /// `init` must have been called.
+    #[inline]
+    pub unsafe fn notify_all(self: Pin<&Self>) {
+        let r = unsafe { libc::pthread_cond_broadcast(self.raw()) };
+        debug_assert_eq!(r, 0);
+    }
+
+    /// # Safety
+    /// * `init` must have been called.
+    /// * `mutex` must be locked by the current thread.
+    /// * This condition variable may only be used with the same mutex.
+    #[inline]
+    pub unsafe fn wait(self: Pin<&Self>, mutex: Pin<&Mutex>) {
+        let r = unsafe { libc::pthread_cond_wait(self.raw(), mutex.raw()) };
+        debug_assert_eq!(r, 0);
+    }
+
+    /// # Safety
+    /// * `init` must have been called.
+    /// * `mutex` must be locked by the current thread.
+    /// * This condition variable may only be used with the same mutex.
+    pub unsafe fn wait_timeout(&self, mutex: Pin<&Mutex>, dur: Duration) -> bool {
+        let mutex = mutex.raw();
+
+        // 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, the timeout is clamped to 1000 years.
+        #[cfg(target_vendor = "apple")]
+        let dur = Duration::min(dur, Duration::from_secs(1000 * 365 * 86400));
+
+        let timeout = Timespec::now(Self::CLOCK).checked_add_duration(&dur);
+
+        #[cfg(not(target_os = "nto"))]
+        let timeout = timeout.and_then(|t| t.to_timespec()).unwrap_or(TIMESPEC_MAX);
+
+        #[cfg(target_os = "nto")]
+        let timeout = timeout.and_then(|t| t.to_timespec_capped()).unwrap_or(TIMESPEC_MAX_CAPPED);
+
+        let r = unsafe { libc::pthread_cond_timedwait(self.raw(), mutex, &timeout) };
+        assert!(r == libc::ETIMEDOUT || r == 0);
+        r == 0
+    }
+}
+
+#[cfg(not(any(
+    target_os = "android",
+    target_vendor = "apple",
+    target_os = "espidf",
+    target_os = "horizon",
+    target_os = "l4re",
+    target_os = "redox",
+    target_os = "teeos",
+)))]
+impl Condvar {
+    pub const PRECISE_TIMEOUT: bool = true;
+    const CLOCK: libc::clockid_t = libc::CLOCK_MONOTONIC;
+
+    /// # Safety
+    /// May only be called once.
+    pub unsafe fn init(self: Pin<&mut Self>) {
+        use crate::mem::MaybeUninit;
+
+        struct AttrGuard<'a>(pub &'a mut MaybeUninit<libc::pthread_condattr_t>);
+        impl Drop for AttrGuard<'_> {
+            fn drop(&mut self) {
+                unsafe {
+                    let result = libc::pthread_condattr_destroy(self.0.as_mut_ptr());
+                    assert_eq!(result, 0);
+                }
+            }
+        }
+
+        unsafe {
+            let mut attr = MaybeUninit::<libc::pthread_condattr_t>::uninit();
+            let r = libc::pthread_condattr_init(attr.as_mut_ptr());
+            assert_eq!(r, 0);
+            let attr = AttrGuard(&mut attr);
+            let r = libc::pthread_condattr_setclock(attr.0.as_mut_ptr(), Self::CLOCK);
+            assert_eq!(r, 0);
+            let r = libc::pthread_cond_init(self.raw(), attr.0.as_ptr());
+            assert_eq!(r, 0);
+        }
+    }
+}
+
+// `pthread_condattr_setclock` is unfortunately not supported on these platforms.
+#[cfg(any(
+    target_os = "android",
+    target_vendor = "apple",
+    target_os = "espidf",
+    target_os = "horizon",
+    target_os = "l4re",
+    target_os = "redox",
+    target_os = "teeos",
+))]
+impl Condvar {
+    pub const PRECISE_TIMEOUT: bool = false;
+    const CLOCK: libc::clockid_t = libc::CLOCK_REALTIME;
+
+    /// # Safety
+    /// May only be called once.
+    pub unsafe fn init(self: Pin<&mut Self>) {
+        if cfg!(any(target_os = "espidf", target_os = "horizon", target_os = "teeos")) {
+            // NOTE: ESP-IDF's PTHREAD_COND_INITIALIZER support is not released yet
+            // So on that platform, init() should always be called.
+            //
+            // Similar story for the 3DS (horizon) and for TEEOS.
+            let r = unsafe { libc::pthread_cond_init(self.raw(), crate::ptr::null()) };
+            assert_eq!(r, 0);
+        }
+    }
+}
+
+impl !Unpin for Condvar {}
+
+unsafe impl Sync for Condvar {}
+unsafe impl Send for Condvar {}
+
+impl Drop for Condvar {
+    #[inline]
+    fn drop(&mut self) {
+        let r = unsafe { libc::pthread_cond_destroy(self.raw()) };
+        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);
+        }
+    }
+}