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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 __ZTFASTLOCK_H__
#define __ZTFASTLOCK_H__
#include "zthread/Exceptions.h"
#include "zthread/NonCopyable.h"
#include "../ThreadOps.h"
#include <windows.h>
#include <assert.h>
namespace ZThread {
/**
* @class FastLock
*
* @author Eric Crahen <http://www.code-foo.com>
* @date <2003-07-16T23:32:44-0400>
* @version 2.2.11
*
* This FastLock implementation is based on a Win32 Mutex
* object. This will perform better under high contention,
* but will not be as fast as the spin lock under reasonable
* circumstances.
*/
class FastLock : private NonCopyable {
HANDLE _hMutex;
#ifndef NDEBUG
volatile bool _locked;
#endif
public:
/**
* Create a new FastLock
*/
FastLock() {
#ifndef NDEBUG
_locked = false;
#endif
_hMutex = ::CreateMutex(0, 0, 0);
assert(_hMutex != NULL);
if(_hMutex == NULL)
throw Initialization_Exception();
}
~FastLock() {
::CloseHandle(_hMutex);
}
void acquire() {
if(::WaitForSingleObject(_hMutex, INFINITE) != WAIT_OBJECT_0) {
assert(0);
throw Synchronization_Exception();
}
#ifndef NDEBUG
// Simulate deadlock to provide consistent behavior. This
// will help avoid errors when porting. Avoiding situations
// where a FastMutex mistakenly behaves as a recursive lock.
while(_locked)
ThreadOps::yield();
_locked = true;
#endif
}
void release() {
#ifndef NDEBUG
_locked = false;
#endif
if(::ReleaseMutex(_hMutex) == 0) {
assert(0);
throw Synchronization_Exception();
}
}
bool tryAcquire(unsigned long timeout = 0) {
switch(::WaitForSingleObject(_hMutex, timeout)) {
case WAIT_OBJECT_0:
#ifndef NDEBUG
// Simulate deadlock to provide consistent behavior. This
// will help avoid errors when porting. Avoiding situations
// where a FastMutex mistakenly behaves as a recursive lock.
while(_locked)
ThreadOps::yield();
_locked = true;
#endif
return true;
case WAIT_TIMEOUT:
return false;
default:
break;
}
assert(0);
throw Synchronization_Exception();
}
};
} // namespace ZThread
#endif
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