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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef BASE_LOCK_IMPL_H__
#define BASE_LOCK_IMPL_H__
#include "base/basictypes.h"
#if defined(WIN32)
#include <Windows.h>
#elif defined(__APPLE__)
#include <libkern/OSAtomic.h>
#endif
// 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:
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();
private:
#if defined(WIN32)
CRITICAL_SECTION critical_section_;
#elif defined(__APPLE__)
OSSpinLock spin_lock_;
#endif
DISALLOW_EVIL_CONSTRUCTORS(LockImpl);
};
class AutoLockImpl {
public:
AutoLockImpl(LockImpl* lock_impl)
: lock_impl_(lock_impl) {
lock_impl_->Lock();
}
~AutoLockImpl() {
lock_impl_->Unlock();
}
private:
DISALLOW_EVIL_CONSTRUCTORS(AutoLockImpl);
LockImpl* lock_impl_;
};
#endif // BASE_LOCK_IMPL_H__
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