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// Copyright (c) 2006-2009 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_H_
#define BASE_LOCK_H_
#include "base/lock_impl.h"
// A convenient wrapper for an OS specific critical section.
class Lock {
public:
Lock() : lock_() {}
~Lock() {}
void Acquire() { lock_.Lock(); }
void Release() { lock_.Unlock(); }
// If the lock is not held, take it and return true. If the lock is already
// held by another thread, immediately return false.
bool Try() { return lock_.Try(); }
// In debug builds this method checks that the lock has been acquired by the
// calling thread. If the lock has not been acquired, then the method
// will DCHECK(). In non-debug builds, the LockImpl's implementation of
// AssertAcquired() is an empty inline method.
void AssertAcquired() const { return lock_.AssertAcquired(); }
// Return the underlying lock implementation.
// TODO(awalker): refactor lock and condition variables so that this is
// unnecessary.
LockImpl* lock_impl() { return &lock_; }
private:
LockImpl lock_; // Platform specific underlying lock implementation.
DISALLOW_COPY_AND_ASSIGN(Lock);
};
// A helper class that acquires the given Lock while the AutoLock is in scope.
class AutoLock {
public:
explicit AutoLock(Lock& lock) : lock_(lock) {
lock_.Acquire();
}
~AutoLock() {
lock_.AssertAcquired();
lock_.Release();
}
private:
Lock& lock_;
DISALLOW_COPY_AND_ASSIGN(AutoLock);
};
// AutoUnlock is a helper that will Release() the |lock| argument in the
// constructor, and re-Acquire() it in the destructor.
class AutoUnlock {
public:
explicit AutoUnlock(Lock& lock) : lock_(lock) {
// We require our caller to have the lock.
lock_.AssertAcquired();
lock_.Release();
}
~AutoUnlock() {
lock_.Acquire();
}
private:
Lock& lock_;
DISALLOW_COPY_AND_ASSIGN(AutoUnlock);
};
#endif // BASE_LOCK_H_
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