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/* -*-c++-*- OpenThreads - Copyright (C) 1998-2007 Robert Osfield
*
* This library is open source and may be redistributed and/or modified under
* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
* (at your option) any later version. The full license is in LICENSE file
* included with this distribution, and on the openscenegraph.org website.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* OpenSceneGraph Public License for more details.
*/
#ifndef _OPENTHREADS_READWRITEMUTEX_
#define _OPENTHREADS_READWRITEMUTEX_
#include <OpenThreads/Thread>
#include <OpenThreads/ReentrantMutex>
namespace OpenThreads {
class ReadWriteMutex
{
public:
ReadWriteMutex():
_readCount(0) {}
virtual ~ReadWriteMutex() {}
virtual int readLock()
{
OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_readCountMutex);
int result = 0;
if (_readCount==0)
{
result = _readWriteMutex.lock();
}
++_readCount;
return result;
}
virtual int readUnlock()
{
OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_readCountMutex);
int result = 0;
if (_readCount>0)
{
--_readCount;
if (_readCount==0)
{
result = _readWriteMutex.unlock();
}
}
return result;
}
virtual int writeLock()
{
return _readWriteMutex.lock();
}
virtual int writeUnlock()
{
return _readWriteMutex.unlock();
}
protected:
ReadWriteMutex(const ReadWriteMutex&) {}
ReadWriteMutex& operator = (const ReadWriteMutex&) { return *(this); }
#if 0
ReentrantMutex _readWriteMutex;
ReentrantMutex _readCountMutex;
#else
OpenThreads::Mutex _readWriteMutex;
OpenThreads::Mutex _readCountMutex;
#endif
unsigned int _readCount;
};
class ScopedReadLock
{
public:
ScopedReadLock(ReadWriteMutex& mutex):_mutex(mutex) { _mutex.readLock(); }
~ScopedReadLock() { _mutex.readUnlock(); }
protected:
ReadWriteMutex& _mutex;
ScopedReadLock& operator = (const ScopedReadLock&) { return *this; }
};
class ScopedWriteLock
{
public:
ScopedWriteLock(ReadWriteMutex& mutex):_mutex(mutex) { _mutex.writeLock(); }
~ScopedWriteLock() { _mutex.writeUnlock(); }
protected:
ReadWriteMutex& _mutex;
ScopedWriteLock& operator = (const ScopedWriteLock&) { return *this; }
};
}
#endif
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