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/*
* Copyright (c) 2005, Eric Crahen
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is furnished
* to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#ifndef __ZTFASTRECURSIVELOCK_H__
#define __ZTFASTRECURSIVELOCK_H__
#include "../FastLock.h"
#include "../ThreadOps.h"
#include <assert.h>
namespace ZThread {
/**
* @class FastRecursiveLock
*
* @author Eric Crahen <http://www.code-foo.com>
* @date <2003-07-16T23:30:59-0400>
* @version 2.2.8
*
* This implementation of a FastRecursiveLock uses the which ever FastLock
* that is selected to create a recursive spin lock.
*/
class FastRecursiveLock : private NonCopyable {
FastLock _lock;
ThreadOps _owner;
volatile unsigned int _count;
public:
inline FastRecursiveLock() : _owner(ThreadOps::INVALID), _count(0) {}
inline ~FastRecursiveLock() {
assert(_owner == ThreadOps::INVALID);
assert(_count == 0);
}
inline void acquire() {
ThreadOps self(ThreadOps::self());
bool wasLocked = false;
do {
_lock.acquire();
// If there is no owner, or the owner is the caller
// update the count
if(_owner == ThreadOps::INVALID || _owner == self) {
_owner = self;
_count++;
wasLocked = true;
}
_lock.release();
} while(!wasLocked);
assert(_owner == ThreadOps::self());
}
inline void release() {
assert(_owner == ThreadOps::self());
_lock.acquire();
if(--_count == 0)
_owner = ThreadOps::INVALID;
_lock.release();
}
inline bool tryAcquire(unsigned long timeout=0) {
ThreadOps self(ThreadOps::self());
bool wasLocked = false;
_lock.acquire();
if(_owner == ThreadOps::INVALID || _owner == self) {
_owner = self;
_count++;
wasLocked = true;
}
_lock.release();
assert(!wasLocked || _owner == ThreadOps::self());
return wasLocked;
}
}; /* FastRecursiveLock */
} // namespace ZThread
#endif
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