4 files changed, 157 insertions, 0 deletions
diff --git a/library/std/src/sys/windows/locks/condvar.rs b/library/std/src/sys/windows/locks/condvar.rs
new file mode 100644
index 000000000..be9a2abbe
--- /dev/null
+++ b/library/std/src/sys/windows/locks/condvar.rs
@@ -0,0 +1,52 @@
+use crate::cell::UnsafeCell;
+use crate::sys::c;
+use crate::sys::locks::{mutex, Mutex};
+use crate::sys::os;
+use crate::time::Duration;
+
+pub struct Condvar {
+    inner: UnsafeCell<c::CONDITION_VARIABLE>,
+}
+
+pub type MovableCondvar = Condvar;
+
+unsafe impl Send for Condvar {}
+unsafe impl Sync for Condvar {}
+
+impl Condvar {
+    #[inline]
+    pub const fn new() -> Condvar {
+        Condvar { inner: UnsafeCell::new(c::CONDITION_VARIABLE_INIT) }
+    }
+
+    #[inline]
+    pub unsafe fn wait(&self, mutex: &Mutex) {
+        let r = c::SleepConditionVariableSRW(self.inner.get(), mutex::raw(mutex), c::INFINITE, 0);
+        debug_assert!(r != 0);
+    }
+
+    pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool {
+        let r = c::SleepConditionVariableSRW(
+            self.inner.get(),
+            mutex::raw(mutex),
+            crate::sys::windows::dur2timeout(dur),
+            0,
+        );
+        if r == 0 {
+            debug_assert_eq!(os::errno() as usize, c::ERROR_TIMEOUT as usize);
+            false
+        } else {
+            true
+        }
+    }
+
+    #[inline]
+    pub unsafe fn notify_one(&self) {
+        c::WakeConditionVariable(self.inner.get())
+    }
+
+    #[inline]
+    pub unsafe fn notify_all(&self) {
+        c::WakeAllConditionVariable(self.inner.get())
+    }
+}
diff --git a/library/std/src/sys/windows/locks/mod.rs b/library/std/src/sys/windows/locks/mod.rs
new file mode 100644
index 000000000..d412ff152
--- /dev/null
+++ b/library/std/src/sys/windows/locks/mod.rs
@@ -0,0 +1,6 @@
+mod condvar;
+mod mutex;
+mod rwlock;
+pub use condvar::{Condvar, MovableCondvar};
+pub use mutex::{MovableMutex, Mutex};
+pub use rwlock::{MovableRwLock, RwLock};
diff --git a/library/std/src/sys/windows/locks/mutex.rs b/library/std/src/sys/windows/locks/mutex.rs
new file mode 100644
index 000000000..f91e8f9f5
--- /dev/null
+++ b/library/std/src/sys/windows/locks/mutex.rs
@@ -0,0 +1,57 @@
+//! System Mutexes
+//!
+//! The Windows implementation of mutexes is a little odd and it might not be
+//! immediately obvious what's going on. The primary oddness is that SRWLock is
+//! used instead of CriticalSection, and this is done because:
+//!
+//! 1. SRWLock is several times faster than CriticalSection according to
+//!    benchmarks performed on both Windows 8 and Windows 7.
+//!
+//! 2. CriticalSection allows recursive locking while SRWLock deadlocks. The
+//!    Unix implementation deadlocks so consistency is preferred. See #19962 for
+//!    more details.
+//!
+//! 3. While CriticalSection is fair and SRWLock is not, the current Rust policy
+//!    is that there are no guarantees of fairness.
+
+use crate::cell::UnsafeCell;
+use crate::sys::c;
+
+pub struct Mutex {
+    srwlock: UnsafeCell<c::SRWLOCK>,
+}
+
+// Windows SRW Locks are movable (while not borrowed).
+pub type MovableMutex = Mutex;
+
+unsafe impl Send for Mutex {}
+unsafe impl Sync for Mutex {}
+
+#[inline]
+pub unsafe fn raw(m: &Mutex) -> c::PSRWLOCK {
+    m.srwlock.get()
+}
+
+impl Mutex {
+    #[inline]
+    pub const fn new() -> Mutex {
+        Mutex { srwlock: UnsafeCell::new(c::SRWLOCK_INIT) }
+    }
+    #[inline]
+    pub unsafe fn init(&mut self) {}
+
+    #[inline]
+    pub unsafe fn lock(&self) {
+        c::AcquireSRWLockExclusive(raw(self));
+    }
+
+    #[inline]
+    pub unsafe fn try_lock(&self) -> bool {
+        c::TryAcquireSRWLockExclusive(raw(self)) != 0
+    }
+
+    #[inline]
+    pub unsafe fn unlock(&self) {
+        c::ReleaseSRWLockExclusive(raw(self));
+    }
+}
diff --git a/library/std/src/sys/windows/locks/rwlock.rs b/library/std/src/sys/windows/locks/rwlock.rs
new file mode 100644
index 000000000..fa5ffe574
--- /dev/null
+++ b/library/std/src/sys/windows/locks/rwlock.rs
@@ -0,0 +1,42 @@
+use crate::cell::UnsafeCell;
+use crate::sys::c;
+
+pub struct RwLock {
+    inner: UnsafeCell<c::SRWLOCK>,
+}
+
+pub type MovableRwLock = RwLock;
+
+unsafe impl Send for RwLock {}
+unsafe impl Sync for RwLock {}
+
+impl RwLock {
+    #[inline]
+    pub const fn new() -> RwLock {
+        RwLock { inner: UnsafeCell::new(c::SRWLOCK_INIT) }
+    }
+    #[inline]
+    pub unsafe fn read(&self) {
+        c::AcquireSRWLockShared(self.inner.get())
+    }
+    #[inline]
+    pub unsafe fn try_read(&self) -> bool {
+        c::TryAcquireSRWLockShared(self.inner.get()) != 0
+    }
+    #[inline]
+    pub unsafe fn write(&self) {
+        c::AcquireSRWLockExclusive(self.inner.get())
+    }
+    #[inline]
+    pub unsafe fn try_write(&self) -> bool {
+        c::TryAcquireSRWLockExclusive(self.inner.get()) != 0
+    }
+    #[inline]
+    pub unsafe fn read_unlock(&self) {
+        c::ReleaseSRWLockShared(self.inner.get())
+    }
+    #[inline]
+    pub unsafe fn write_unlock(&self) {
+        c::ReleaseSRWLockExclusive(self.inner.get())
+    }
+}