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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_LOCK_IMPL_H_
#define BASE_LOCK_IMPL_H_
#include "build/build_config.h"
#if defined(OS_WIN)
#include <windows.h>
#elif defined(OS_POSIX)
#include <pthread.h>
#endif
#include "base/basictypes.h"
#include "base/platform_thread.h"
// This class implements the underlying platform-specific spin-lock mechanism
// used for the Lock class. Most users should not use LockImpl directly, but
// should instead use Lock.
class LockImpl {
public:
#if defined(OS_WIN)
typedef CRITICAL_SECTION OSLockType;
#elif defined(OS_POSIX)
typedef pthread_mutex_t OSLockType;
#endif
LockImpl();
~LockImpl();
// If the lock is not held, take it and return true. If the lock is already
// held by something else, immediately return false.
bool Try();
// Take the lock, blocking until it is available if necessary.
void Lock();
// Release the lock. This must only be called by the lock's holder: after
// a successful call to Try, or a call to Lock.
void Unlock();
// Debug-only method that will DCHECK() if the lock is not acquired by the
// current thread. In non-debug builds, no check is performed.
// Because linux and mac condition variables modify the underlyning lock
// through the os_lock() method, runtime assertions can not be done on those
// builds.
#if defined(NDEBUG) || !defined(OS_WIN)
void AssertAcquired() const {}
#else
void AssertAcquired() const;
#endif
// Return the native underlying lock. Not supported for Windows builds.
// TODO(awalker): refactor lock and condition variables so that this is
// unnecessary.
#if !defined(OS_WIN)
OSLockType* os_lock() { return &os_lock_; }
#endif
private:
OSLockType os_lock_;
#if !defined(NDEBUG) && defined(OS_WIN)
// All private data is implicitly protected by lock_.
// Be VERY careful to only access members under that lock.
PlatformThreadId owning_thread_id_;
int32_t recursion_count_shadow_;
bool recursion_used_; // Allow debugging to continued after a DCHECK().
#endif // NDEBUG
DISALLOW_COPY_AND_ASSIGN(LockImpl);
};
#endif // BASE_LOCK_IMPL_H_
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