1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/ipc/chromium/src/base/lock_impl_win.cc Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,73 @@
1.4 +// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
1.5 +// Use of this source code is governed by a BSD-style license that can be
1.6 +// found in the LICENSE file.
1.7 +
1.8 +#include "base/lock_impl.h"
1.9 +#include "base/logging.h"
1.10 +
1.11 +// NOTE: Although windows critical sections support recursive locks, we do not
1.12 +// allow this, and we will commonly fire a DCHECK() if a thread attempts to
1.13 +// acquire the lock a second time (while already holding it).
1.14 +
1.15 +LockImpl::LockImpl() {
1.16 +#ifndef NDEBUG
1.17 + recursion_count_shadow_ = 0;
1.18 + recursion_used_ = false;
1.19 + owning_thread_id_ = 0;
1.20 +#endif // NDEBUG
1.21 + // The second parameter is the spin count, for short-held locks it avoid the
1.22 + // contending thread from going to sleep which helps performance greatly.
1.23 + ::InitializeCriticalSectionAndSpinCount(&os_lock_, 2000);
1.24 +}
1.25 +
1.26 +LockImpl::~LockImpl() {
1.27 + ::DeleteCriticalSection(&os_lock_);
1.28 +}
1.29 +
1.30 +bool LockImpl::Try() {
1.31 + if (::TryEnterCriticalSection(&os_lock_) != FALSE) {
1.32 +#ifndef NDEBUG
1.33 + // ONLY access data after locking.
1.34 + owning_thread_id_ = PlatformThread::CurrentId();
1.35 + DCHECK_NE(owning_thread_id_, 0);
1.36 + recursion_count_shadow_++;
1.37 + if (2 == recursion_count_shadow_ && !recursion_used_) {
1.38 + recursion_used_ = true;
1.39 + DCHECK(false); // Catch accidental redundant lock acquisition.
1.40 + }
1.41 +#endif
1.42 + return true;
1.43 + }
1.44 + return false;
1.45 +}
1.46 +
1.47 +void LockImpl::Lock() {
1.48 + ::EnterCriticalSection(&os_lock_);
1.49 +#ifndef NDEBUG
1.50 + // ONLY access data after locking.
1.51 + owning_thread_id_ = PlatformThread::CurrentId();
1.52 + DCHECK_NE(owning_thread_id_, 0);
1.53 + recursion_count_shadow_++;
1.54 + if (2 == recursion_count_shadow_ && !recursion_used_) {
1.55 + recursion_used_ = true;
1.56 + DCHECK(false); // Catch accidental redundant lock acquisition.
1.57 + }
1.58 +#endif // NDEBUG
1.59 +}
1.60 +
1.61 +void LockImpl::Unlock() {
1.62 +#ifndef NDEBUG
1.63 + --recursion_count_shadow_; // ONLY access while lock is still held.
1.64 + DCHECK(0 <= recursion_count_shadow_);
1.65 + owning_thread_id_ = 0;
1.66 +#endif // NDEBUG
1.67 + ::LeaveCriticalSection(&os_lock_);
1.68 +}
1.69 +
1.70 +// In non-debug builds, this method is declared as an empty inline method.
1.71 +#ifndef NDEBUG
1.72 +void LockImpl::AssertAcquired() const {
1.73 + DCHECK(recursion_count_shadow_ > 0);
1.74 + DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId());
1.75 +}
1.76 +#endif
