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/*
* libjingle
* Copyright 2011, Google Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 TALK_BASE_SHAREDEXCLUSIVELOCK_H_
#define TALK_BASE_SHAREDEXCLUSIVELOCK_H_
#include "talk/base/constructormagic.h"
#include "talk/base/criticalsection.h"
#include "talk/base/event.h"
namespace talk_base {
// This class provides shared-exclusive lock. It can be used in cases like
// multiple-readers/single-writer model.
class SharedExclusiveLock {
public:
SharedExclusiveLock();
// Locking/unlocking methods. It is encouraged to use SharedScope or
// ExclusiveScope for protection.
void LockExclusive();
void UnlockExclusive();
void LockShared();
void UnlockShared();
private:
talk_base::CriticalSection cs_exclusive_;
talk_base::CriticalSection cs_shared_;
talk_base::Event shared_count_is_zero_;
int shared_count_;
DISALLOW_COPY_AND_ASSIGN(SharedExclusiveLock);
};
class SharedScope {
public:
explicit SharedScope(SharedExclusiveLock* lock) : lock_(lock) {
lock_->LockShared();
}
~SharedScope() {
lock_->UnlockShared();
}
private:
SharedExclusiveLock* lock_;
DISALLOW_COPY_AND_ASSIGN(SharedScope);
};
class ExclusiveScope {
public:
explicit ExclusiveScope(SharedExclusiveLock* lock) : lock_(lock) {
lock_->LockExclusive();
}
~ExclusiveScope() {
lock_->UnlockExclusive();
}
private:
SharedExclusiveLock* lock_;
DISALLOW_COPY_AND_ASSIGN(ExclusiveScope);
};
} // namespace talk_base
#endif // TALK_BASE_SHAREDEXCLUSIVELOCK_H_
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