1 files changed, 72 insertions, 0 deletions
diff --git a/library/std/src/sys_common/condvar.rs b/library/std/src/sys_common/condvar.rs
new file mode 100644
index 00000000000..f9611bc6f7b
--- /dev/null
+++ b/library/std/src/sys_common/condvar.rs
@@ -0,0 +1,72 @@
+use crate::sys::condvar as imp;
+use crate::sys_common::mutex::{self, Mutex};
+use crate::time::Duration;
+
+/// An OS-based condition variable.
+///
+/// This structure is the lowest layer possible on top of the OS-provided
+/// condition variables. It is consequently entirely unsafe to use. It is
+/// recommended to use the safer types at the top level of this crate instead of
+/// this type.
+pub struct Condvar(imp::Condvar);
+
+impl Condvar {
+    /// Creates a new condition variable for use.
+    ///
+    /// Behavior is undefined if the condition variable is moved after it is
+    /// first used with any of the functions below.
+    pub const fn new() -> Condvar {
+        Condvar(imp::Condvar::new())
+    }
+
+    /// Prepares the condition variable for use.
+    ///
+    /// This should be called once the condition variable is at a stable memory
+    /// address.
+    #[inline]
+    pub unsafe fn init(&mut self) {
+        self.0.init()
+    }
+
+    /// Signals one waiter on this condition variable to wake up.
+    #[inline]
+    pub unsafe fn notify_one(&self) {
+        self.0.notify_one()
+    }
+
+    /// Awakens all current waiters on this condition variable.
+    #[inline]
+    pub unsafe fn notify_all(&self) {
+        self.0.notify_all()
+    }
+
+    /// Waits for a signal on the specified mutex.
+    ///
+    /// Behavior is undefined if the mutex is not locked by the current thread.
+    /// Behavior is also undefined if more than one mutex is used concurrently
+    /// on this condition variable.
+    #[inline]
+    pub unsafe fn wait(&self, mutex: &Mutex) {
+        self.0.wait(mutex::raw(mutex))
+    }
+
+    /// Waits for a signal on the specified mutex with a timeout duration
+    /// specified by `dur` (a relative time into the future).
+    ///
+    /// Behavior is undefined if the mutex is not locked by the current thread.
+    /// Behavior is also undefined if more than one mutex is used concurrently
+    /// on this condition variable.
+    #[inline]
+    pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool {
+        self.0.wait_timeout(mutex::raw(mutex), dur)
+    }
+
+    /// Deallocates all resources associated with this condition variable.
+    ///
+    /// Behavior is undefined if there are current or will be future users of
+    /// this condition variable.
+    #[inline]
+    pub unsafe fn destroy(&self) {
+        self.0.destroy()
+    }
+}