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Diffstat (limited to 'dep/src/zthread/linux/AtomicFastLock.h')
-rw-r--r-- | dep/src/zthread/linux/AtomicFastLock.h | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/dep/src/zthread/linux/AtomicFastLock.h b/dep/src/zthread/linux/AtomicFastLock.h new file mode 100644 index 00000000000..b9aa1babcd6 --- /dev/null +++ b/dep/src/zthread/linux/AtomicFastLock.h @@ -0,0 +1,117 @@ +/* + * 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/NonCopyable.h" +#include "../ThreadOps.h" +#include <assert.h> +#include <asm/atomic.h> + +#if !defined(NDEBUG) +# include <pthread.h> +#endif + +namespace ZThread { + +/** + * @class FastLock + * + * @author Eric Crahen <http://www.code-foo.com> + * @date <2003-07-16T23:27:03-0400> + * @version 2.2.0 + * + * This implementation of a FastLock uses the atomic operations that + * linux provides with its kernel sources. This demonstrates how to implement + * a spinlock with a decrement and test primative. + */ +class FastLock : private NonCopyable { + + atomic_t _value; + +#if !defined(NDEBUG) + pthread_t _owner; +#endif + +public: + + inline FastLock() { + + atomic_t tmp = ATOMIC_INIT(1); + _value = tmp; + + } + + inline ~FastLock() { + + assert(atomic_read(&_value) == 1); + assert(_owner == 0); + + } + + inline void acquire() { + + while(!atomic_dec_and_test(&_value)) { + + atomic_inc(&_value); + ThreadOps::yield(); + + } + +#if !defined(NDEBUG) + _owner = pthread_self(); +#endif + } + + inline void release() { + +#if !defined(NDEBUG) + assert(pthread_equal(_owner, pthread_self()) != 0); +#endif + + atomic_inc(&_value); + _owner = 0; + + } + + inline bool tryAcquire(unsigned long timeout=0) { + + bool wasLocked = atomic_dec_and_test(&_value); + if(!wasLocked) + atomic_inc(&_value); + +#if !defined(NDEBUG) + if(wasLocked) + _owner = pthread_self(); +#endif + + return wasLocked; + + } + +}; /* FastLock */ + + +} // namespace ZThread + +#endif |