59 lines
1.7 KiB
Rust
59 lines
1.7 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use marker::Sync;
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use cell::UnsafeCell;
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use sys::sync as ffi;
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pub struct Mutex { inner: UnsafeCell<ffi::SRWLOCK> }
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pub const MUTEX_INIT: Mutex = Mutex {
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inner: UnsafeCell { value: ffi::SRWLOCK_INIT }
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};
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unsafe impl Sync for Mutex {}
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#[inline]
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pub unsafe fn raw(m: &Mutex) -> ffi::PSRWLOCK {
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m.inner.get()
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}
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// So you might be asking why we're using SRWLock instead of CriticalSection?
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//
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// 1. SRWLock is several times faster than CriticalSection according to benchmarks performed on both
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// Windows 8 and Windows 7.
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//
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// 2. CriticalSection allows recursive locking while SRWLock deadlocks. The Unix implementation
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// deadlocks so consistency is preferred. See #19962 for more details.
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//
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// 3. While CriticalSection is fair and SRWLock is not, the current Rust policy is there there are
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// no guarantees of fairness.
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impl Mutex {
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#[inline]
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pub unsafe fn new() -> Mutex { MUTEX_INIT }
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#[inline]
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pub unsafe fn lock(&self) {
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ffi::AcquireSRWLockExclusive(self.inner.get())
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}
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#[inline]
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pub unsafe fn try_lock(&self) -> bool {
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ffi::TryAcquireSRWLockExclusive(self.inner.get()) != 0
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}
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#[inline]
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pub unsafe fn unlock(&self) {
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ffi::ReleaseSRWLockExclusive(self.inner.get())
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}
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#[inline]
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pub unsafe fn destroy(&self) {
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// ...
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}
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}
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