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/* This file implements atomic counters using __atomic or __sync macros if
* available, otherwise synchronizing different threads using a mutex.
*
* The exported interaface is composed of three macros:
*
* atomicIncr(var,count,mutex) -- Increment the atomic counter
* atomicDecr(var,count,mutex) -- Decrement the atomic counter
* atomicGet(var,dstvar,mutex) -- Fetch the atomic counter value
*
* If atomic primitives are availble (tested in config.h) the mutex
* is not used.
*
* Never use return value from the macros. To update and get use instead:
*
* atomicIncr(mycounter,...);
* atomicGet(mycounter,newvalue);
* doSomethingWith(newvalue);
*
* ----------------------------------------------------------------------------
*
* Copyright (c) 2015, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.
*/
#include <pthread.h>
#ifndef __ATOMIC_VAR_H
#define __ATOMIC_VAR_H
#if defined(__ATOMIC_RELAXED) && !defined(__sun) && (!defined(__clang__) || !defined(__APPLE__) || __apple_build_version__ > 4210057)
/* Implementation using __atomic macros. */
#define atomicIncr(var,count,mutex) __atomic_add_fetch(&var,(count),__ATOMIC_RELAXED)
#define atomicDecr(var,count,mutex) __atomic_sub_fetch(&var,(count),__ATOMIC_RELAXED)
#define atomicGet(var,dstvar,mutex) do { \
dstvar = __atomic_load_n(&var,__ATOMIC_RELAXED); \
} while(0)
#elif defined(HAVE_ATOMIC)
/* Implementation using __sync macros. */
#define atomicIncr(var,count,mutex) __sync_add_and_fetch(&var,(count))
#define atomicDecr(var,count,mutex) __sync_sub_and_fetch(&var,(count))
#define atomicGet(var,dstvar,mutex) do { \
dstvar = __sync_sub_and_fetch(&var,0); \
} while(0)
#else
/* Implementation using pthread mutex. */
#define atomicIncr(var,count,mutex) do { \
pthread_mutex_lock(&mutex); \
var += (count); \
pthread_mutex_unlock(&mutex); \
} while(0)
#define atomicDecr(var,count,mutex) do { \
pthread_mutex_lock(&mutex); \
var -= (count); \
pthread_mutex_unlock(&mutex); \
} while(0)
#define atomicGet(var,dstvar,mutex) do { \
pthread_mutex_lock(&mutex); \
dstvar = var; \
pthread_mutex_unlock(&mutex); \
} while(0)
#endif
#endif /* __ATOMIC_VAR_H */
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