ralphl@chromium.org
5a98eadfaa
Also changed Lock::AssertAcquired to be const function (it already was const, in practice, just not declared that way). Review URL: http://codereview.chromium.org/42402 git-svn-id: svn://svn.chromium.org/chrome/trunk/src@12157 0039d316-1c4b-4281-b951-d872f2087c98
74 linhas
2.2 KiB
C++
74 linhas
2.2 KiB
C++
// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/lock_impl.h"
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#include "base/logging.h"
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// NOTE: Although windows critical sections support recursive locks, we do not
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// allow this, and we will commonly fire a DCHECK() if a thread attempts to
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// acquire the lock a second time (while already holding it).
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LockImpl::LockImpl() {
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#ifndef NDEBUG
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recursion_count_shadow_ = 0;
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recursion_used_ = false;
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owning_thread_id_ = 0;
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#endif // NDEBUG
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// The second parameter is the spin count, for short-held locks it avoid the
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// contending thread from going to sleep which helps performance greatly.
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::InitializeCriticalSectionAndSpinCount(&os_lock_, 2000);
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}
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LockImpl::~LockImpl() {
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::DeleteCriticalSection(&os_lock_);
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}
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bool LockImpl::Try() {
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if (::TryEnterCriticalSection(&os_lock_) != FALSE) {
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#ifndef NDEBUG
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// ONLY access data after locking.
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owning_thread_id_ = PlatformThread::CurrentId();
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DCHECK_NE(owning_thread_id_, 0);
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recursion_count_shadow_++;
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if (2 == recursion_count_shadow_ && !recursion_used_) {
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recursion_used_ = true;
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DCHECK(false); // Catch accidental redundant lock acquisition.
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}
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#endif
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return true;
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}
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return false;
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}
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void LockImpl::Lock() {
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::EnterCriticalSection(&os_lock_);
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#ifndef NDEBUG
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// ONLY access data after locking.
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owning_thread_id_ = PlatformThread::CurrentId();
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DCHECK_NE(owning_thread_id_, 0);
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recursion_count_shadow_++;
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if (2 == recursion_count_shadow_ && !recursion_used_) {
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recursion_used_ = true;
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DCHECK(false); // Catch accidental redundant lock acquisition.
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}
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#endif // NDEBUG
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}
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void LockImpl::Unlock() {
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#ifndef NDEBUG
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--recursion_count_shadow_; // ONLY access while lock is still held.
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DCHECK(0 <= recursion_count_shadow_);
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owning_thread_id_ = 0;
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#endif // NDEBUG
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::LeaveCriticalSection(&os_lock_);
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}
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// In non-debug builds, this method is declared as an empty inline method.
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#ifndef NDEBUG
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void LockImpl::AssertAcquired() const {
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DCHECK(recursion_count_shadow_ > 0);
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DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId());
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}
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#endif
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