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/* This header supplies atomic operations. So far, we rely on GCC's
* atomic builtins. During configure, we check if atomic operatons are
* available. If they are not, I am making the necessary provisioning to live without them if
* they are not available. Please note that you should only use the macros
* here if you think you can actually live WITHOUT an explicit atomic operation,
* because in the non-presence of them, we simply do it without atomicitiy.
* Which, for word-aligned data types, usually (but only usually!) should work.
*
* We are using the functions described in
* http:/gcc.gnu.org/onlinedocs/gcc/Atomic-Builtins.html
*
* THESE MACROS MUST ONLY BE USED WITH WORD-SIZED DATA TYPES!
*
* Copyright 2008-2012 Rainer Gerhards and Adiscon GmbH.
*
* This file is part of the rsyslog runtime library.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
* -or-
* see COPYING.ASL20 in the source distribution
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef INCLUDED_ATOMIC_H
#define INCLUDED_ATOMIC_H
#include <time.h>
#include "typedefs.h"
/* for this release, we disable atomic calls because there seem to be some
* portability problems and we can not fix that without destabilizing the build.
* They simply came in too late. -- rgerhards, 2008-04-02
*/
#ifdef HAVE_ATOMIC_BUILTINS
# define ATOMIC_SUB(data, val, phlpmut) __sync_fetch_and_sub(data, val)
# define ATOMIC_ADD(data, val) __sync_fetch_and_add(&(data), val)
# define ATOMIC_INC(data, phlpmut) ((void) __sync_fetch_and_add(data, 1))
# define ATOMIC_INC_AND_FETCH_int(data, phlpmut) __sync_fetch_and_add(data, 1)
# define ATOMIC_INC_AND_FETCH_unsigned(data, phlpmut) __sync_fetch_and_add(data, 1)
# define ATOMIC_DEC(data, phlpmut) ((void) __sync_sub_and_fetch(data, 1))
# define ATOMIC_DEC_AND_FETCH(data, phlpmut) __sync_sub_and_fetch(data, 1)
# define ATOMIC_FETCH_32BIT(data, phlpmut) ((unsigned) __sync_fetch_and_and(data, 0xffffffff))
# define ATOMIC_STORE_1_TO_32BIT(data) __sync_lock_test_and_set(&(data), 1)
# define ATOMIC_STORE_0_TO_INT(data, phlpmut) __sync_fetch_and_and(data, 0)
# define ATOMIC_STORE_1_TO_INT(data, phlpmut) __sync_fetch_and_or(data, 1)
# define ATOMIC_STORE_INT_TO_INT(data, val) __sync_fetch_and_or(&(data), (val))
# define ATOMIC_CAS(data, oldVal, newVal, phlpmut) __sync_bool_compare_and_swap(data, (oldVal), (newVal))
# define ATOMIC_CAS_time_t(data, oldVal, newVal, phlpmut) __sync_bool_compare_and_swap(data, (oldVal), (newVal))
# define ATOMIC_CAS_VAL(data, oldVal, newVal, phlpmut) __sync_val_compare_and_swap(data, (oldVal), (newVal));
/* functions below are not needed if we have atomics */
# define DEF_ATOMIC_HELPER_MUT(x)
# define INIT_ATOMIC_HELPER_MUT(x)
# define DESTROY_ATOMIC_HELPER_MUT(x)
/* the following operations should preferrably be done atomic, but it is
* not fatal if not -- that means we can live with some missed updates. So be
* sure to use these macros only if that really does not matter!
*/
# define PREFER_ATOMIC_INC(data) ((void) __sync_fetch_and_add(&(data), 1))
#else
/* note that we gained parctical proof that theoretical problems DO occur
* if we do not properly address them. See this blog post for details:
* http://blog.gerhards.net/2009/01/rsyslog-data-race-analysis.html
* The bottom line is that if there are no atomics available, we should NOT
* simply go ahead and do without them - use mutexes or other things. The
* code needs to be checked against all those cases. -- rgerhards, 2009-01-30
*/
#include <pthread.h>
# define ATOMIC_INC(data, phlpmut) { \
pthread_mutex_lock(phlpmut); \
++(*(data)); \
pthread_mutex_unlock(phlpmut); \
}
# define ATOMIC_STORE_0_TO_INT(data, hlpmut) { \
pthread_mutex_lock(hlpmut); \
*(data) = 0; \
pthread_mutex_unlock(hlpmut); \
}
# define ATOMIC_STORE_1_TO_INT(data, hlpmut) { \
pthread_mutex_lock(hlpmut); \
*(data) = 1; \
pthread_mutex_unlock(hlpmut); \
}
static inline int
ATOMIC_CAS(int *data, int oldVal, int newVal, pthread_mutex_t *phlpmut) {
int bSuccess;
pthread_mutex_lock(phlpmut);
if(*data == oldVal) {
*data = newVal;
bSuccess = 1;
} else {
bSuccess = 0;
}
pthread_mutex_unlock(phlpmut);
return(bSuccess);
}
static inline int
ATOMIC_CAS_time_t(time_t *data, time_t oldVal, time_t newVal, pthread_mutex_t *phlpmut) {
int bSuccess;
pthread_mutex_lock(phlpmut);
if(*data == oldVal) {
*data = newVal;
bSuccess = 1;
} else {
bSuccess = 0;
}
pthread_mutex_unlock(phlpmut);
return(bSuccess);
}
static inline int
ATOMIC_CAS_VAL(int *data, int oldVal, int newVal, pthread_mutex_t *phlpmut) {
int val;
pthread_mutex_lock(phlpmut);
if(*data == oldVal) {
*data = newVal;
}
val = *data;
pthread_mutex_unlock(phlpmut);
return(val);
}
# define ATOMIC_DEC(data, phlpmut) { \
pthread_mutex_lock(phlpmut); \
--(*(data)); \
pthread_mutex_unlock(phlpmut); \
}
static inline int
ATOMIC_INC_AND_FETCH_int(int *data, pthread_mutex_t *phlpmut) {
int val;
pthread_mutex_lock(phlpmut);
val = ++(*data);
pthread_mutex_unlock(phlpmut);
return(val);
}
static inline unsigned
ATOMIC_INC_AND_FETCH_unsigned(unsigned *data, pthread_mutex_t *phlpmut) {
unsigned val;
pthread_mutex_lock(phlpmut);
val = ++(*data);
pthread_mutex_unlock(phlpmut);
return(val);
}
static inline int
ATOMIC_DEC_AND_FETCH(int *data, pthread_mutex_t *phlpmut) {
int val;
pthread_mutex_lock(phlpmut);
val = --(*data);
pthread_mutex_unlock(phlpmut);
return(val);
}
static inline int
ATOMIC_FETCH_32BIT(int *data, pthread_mutex_t *phlpmut) {
int val;
pthread_mutex_lock(phlpmut);
val = (*data);
pthread_mutex_unlock(phlpmut);
return(val);
}
static inline void
ATOMIC_SUB(int *data, int val, pthread_mutex_t *phlpmut) {
pthread_mutex_lock(phlpmut);
(*data) -= val;
pthread_mutex_unlock(phlpmut);
}
# define DEF_ATOMIC_HELPER_MUT(x) pthread_mutex_t x
# define INIT_ATOMIC_HELPER_MUT(x) pthread_mutex_init(&(x), NULL)
# define DESTROY_ATOMIC_HELPER_MUT(x) pthread_mutex_destroy(&(x))
# define PREFER_ATOMIC_INC(data) ((void) ++data)
#endif
/* we need to handle 64bit atomics seperately as some platforms have
* 32 bit atomics, but not 64 biot ones... -- rgerhards, 2010-12-01
*/
#ifdef HAVE_ATOMIC_BUILTINS_64BIT
# define ATOMIC_INC_uint64(data, phlpmut) ((void) __sync_fetch_and_add(data, 1))
# define ATOMIC_DEC_unit64(data, phlpmut) ((void) __sync_sub_and_fetch(data, 1))
# define ATOMIC_INC_AND_FETCH_uint64(data, phlpmut) __sync_fetch_and_add(data, 1)
# define DEF_ATOMIC_HELPER_MUT64(x)
# define INIT_ATOMIC_HELPER_MUT64(x)
# define DESTROY_ATOMIC_HELPER_MUT64(x)
#else
# define ATOMIC_INC_uint64(data, phlpmut) { \
pthread_mutex_lock(phlpmut); \
++(*(data)); \
pthread_mutex_unlock(phlpmut); \
}
# define ATOMIC_DEC_uint64(data, phlpmut) { \
pthread_mutex_lock(phlpmut); \
--(*(data)); \
pthread_mutex_unlock(phlpmut); \
}
static inline unsigned
ATOMIC_INC_AND_FETCH_uint64(uint64 *data, pthread_mutex_t *phlpmut) {
uint64 val;
pthread_mutex_lock(phlpmut);
val = ++(*data);
pthread_mutex_unlock(phlpmut);
return(val);
}
# define DEF_ATOMIC_HELPER_MUT64(x) pthread_mutex_t x
# define INIT_ATOMIC_HELPER_MUT64(x) pthread_mutex_init(&(x), NULL)
# define DESTROY_ATOMIC_HELPER_MUT64(x) pthread_mutex_destroy(&(x))
#endif /* #ifdef HAVE_ATOMIC_BUILTINS_64BIT */
#endif /* #ifndef INCLUDED_ATOMIC_H */
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