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212 lines
7.3 KiB
C
212 lines
7.3 KiB
C
/* This header supplies atomic operations. So far, we rely on GCC's
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* atomic builtins. During configure, we check if atomic operatons are
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* available. If they are not, I am making the necessary provisioning to live without them if
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* they are not available. Please note that you should only use the macros
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* here if you think you can actually live WITHOUT an explicit atomic operation,
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* because in the non-presence of them, we simply do it without atomicitiy.
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* Which, for word-aligned data types, usually (but only usually!) should work.
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*
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* We are using the functions described in
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* http:/gcc.gnu.org/onlinedocs/gcc/Atomic-Builtins.html
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*
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* THESE MACROS MUST ONLY BE USED WITH WORD-SIZED DATA TYPES!
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*
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* Copyright 2008 Rainer Gerhards and Adiscon GmbH.
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*
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* This file is part of the rsyslog runtime library.
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*
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* The rsyslog runtime library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* The rsyslog runtime library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with the rsyslog runtime library. If not, see <http://www.gnu.org/licenses/>.
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*
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* A copy of the GPL can be found in the file "COPYING" in this distribution.
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* A copy of the LGPL can be found in the file "COPYING.LESSER" in this distribution.
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*/
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#ifndef INCLUDED_ATOMIC_H
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#define INCLUDED_ATOMIC_H
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#include <time.h>
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#include "typedefs.h"
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/* for this release, we disable atomic calls because there seem to be some
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* portability problems and we can not fix that without destabilizing the build.
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* They simply came in too late. -- rgerhards, 2008-04-02
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*/
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#ifdef HAVE_ATOMIC_BUILTINS
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# define ATOMIC_SUB(data, val, phlpmut) __sync_fetch_and_sub(data, val)
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# define ATOMIC_ADD(data, val) __sync_fetch_and_add(&(data), val)
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# define ATOMIC_INC(data, phlpmut) ((void) __sync_fetch_and_add(data, 1))
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# define ATOMIC_INC_AND_FETCH_int(data, phlpmut) __sync_fetch_and_add(data, 1)
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# define ATOMIC_INC_AND_FETCH_unsigned(data, phlpmut) __sync_fetch_and_add(data, 1)
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# define ATOMIC_INC_AND_FETCH_uint64(data, phlpmut) __sync_fetch_and_add(data, 1)
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# define ATOMIC_DEC(data, phlpmut) ((void) __sync_sub_and_fetch(data, 1))
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# define ATOMIC_DEC_AND_FETCH(data, phlpmut) __sync_sub_and_fetch(data, 1)
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# define ATOMIC_FETCH_32BIT(data, phlpmut) ((unsigned) __sync_fetch_and_and(data, 0xffffffff))
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# define ATOMIC_STORE_1_TO_32BIT(data) __sync_lock_test_and_set(&(data), 1)
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# define ATOMIC_STORE_0_TO_INT(data, phlpmut) __sync_fetch_and_and(data, 0)
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# define ATOMIC_STORE_1_TO_INT(data, phlpmut) __sync_fetch_and_or(data, 1)
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# define ATOMIC_STORE_INT_TO_INT(data, val) __sync_fetch_and_or(&(data), (val))
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# define ATOMIC_CAS(data, oldVal, newVal, phlpmut) __sync_bool_compare_and_swap(data, (oldVal), (newVal))
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# define ATOMIC_CAS_time_t(data, oldVal, newVal, phlpmut) __sync_bool_compare_and_swap(data, (oldVal), (newVal))
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# define ATOMIC_CAS_VAL(data, oldVal, newVal, phlpmut) __sync_val_compare_and_swap(data, (oldVal), (newVal));
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/* functions below are not needed if we have atomics */
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# define DEF_ATOMIC_HELPER_MUT(x)
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# define INIT_ATOMIC_HELPER_MUT(x)
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# define DESTROY_ATOMIC_HELPER_MUT(x)
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/* the following operations should preferrably be done atomic, but it is
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* not fatal if not -- that means we can live with some missed updates. So be
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* sure to use these macros only if that really does not matter!
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*/
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# define PREFER_ATOMIC_INC(data) ((void) __sync_fetch_and_add(&(data), 1))
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#else
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/* note that we gained parctical proof that theoretical problems DO occur
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* if we do not properly address them. See this blog post for details:
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* http://blog.gerhards.net/2009/01/rsyslog-data-race-analysis.html
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* The bottom line is that if there are no atomics available, we should NOT
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* simply go ahead and do without them - use mutexes or other things. The
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* code needs to be checked against all those cases. -- rgerhards, 2009-01-30
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*/
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#include <pthread.h>
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# define ATOMIC_INC(data, phlpmut) { \
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pthread_mutex_lock(phlpmut); \
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++(*(data)); \
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pthread_mutex_unlock(phlpmut); \
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}
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# define ATOMIC_STORE_0_TO_INT(data, hlpmut) { \
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pthread_mutex_lock(hlpmut); \
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*(data) = 0; \
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pthread_mutex_unlock(hlpmut); \
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}
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# define ATOMIC_STORE_1_TO_INT(data, hlpmut) { \
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pthread_mutex_lock(hlpmut); \
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*(data) = 1; \
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pthread_mutex_unlock(hlpmut); \
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}
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static inline int
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ATOMIC_CAS(int *data, int oldVal, int newVal, pthread_mutex_t *phlpmut) {
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int bSuccess;
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pthread_mutex_lock(phlpmut);
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if(*data == oldVal) {
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*data = newVal;
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bSuccess = 1;
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} else {
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bSuccess = 0;
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}
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pthread_mutex_unlock(phlpmut);
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return(bSuccess);
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}
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static inline int
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ATOMIC_CAS_time_t(time_t *data, time_t oldVal, time_t newVal, pthread_mutex_t *phlpmut) {
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int bSuccess;
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pthread_mutex_lock(phlpmut);
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if(*data == oldVal) {
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*data = newVal;
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bSuccess = 1;
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} else {
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bSuccess = 0;
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}
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pthread_mutex_unlock(phlpmut);
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return(bSuccess);
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}
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static inline int
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ATOMIC_CAS_VAL(int *data, int oldVal, int newVal, pthread_mutex_t *phlpmut) {
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int val;
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pthread_mutex_lock(phlpmut);
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if(*data == oldVal) {
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*data = newVal;
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}
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val = *data;
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pthread_mutex_unlock(phlpmut);
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return(val);
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}
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# define ATOMIC_DEC(data, phlpmut) { \
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pthread_mutex_lock(phlpmut); \
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--(*(data)); \
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pthread_mutex_unlock(phlpmut); \
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}
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static inline int
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ATOMIC_INC_AND_FETCH_int(int *data, pthread_mutex_t *phlpmut) {
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int val;
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pthread_mutex_lock(phlpmut);
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val = ++(*data);
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pthread_mutex_unlock(phlpmut);
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return(val);
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}
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static inline unsigned
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ATOMIC_INC_AND_FETCH_unsigned(unsigned *data, pthread_mutex_t *phlpmut) {
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unsigned val;
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pthread_mutex_lock(phlpmut);
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val = ++(*data);
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pthread_mutex_unlock(phlpmut);
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return(val);
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}
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static inline unsigned
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ATOMIC_INC_AND_FETCH_uint64(uint64 *data, pthread_mutex_t *phlpmut) {
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uint64 val;
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pthread_mutex_lock(phlpmut);
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val = ++(*data);
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pthread_mutex_unlock(phlpmut);
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return(val);
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}
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static inline int
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ATOMIC_DEC_AND_FETCH(int *data, pthread_mutex_t *phlpmut) {
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int val;
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pthread_mutex_lock(phlpmut);
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val = --(*data);
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pthread_mutex_unlock(phlpmut);
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return(val);
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}
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static inline int
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ATOMIC_FETCH_32BIT(int *data, pthread_mutex_t *phlpmut) {
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int val;
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pthread_mutex_lock(phlpmut);
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val = (*data);
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pthread_mutex_unlock(phlpmut);
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return(val);
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}
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static inline void
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ATOMIC_SUB(int *data, int val, pthread_mutex_t *phlpmut) {
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pthread_mutex_lock(phlpmut);
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(*data) -= val;
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pthread_mutex_unlock(phlpmut);
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}
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#if 0
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# warning "atomic builtins not available, using nul operations - rsyslogd will probably be racy!"
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# define ATOMIC_INC_AND_FETCH_int(data) (++(data))
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# define ATOMIC_INC_AND_FETCH_unsigned(data) (++(data))
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# define ATOMIC_INC_AND_FETCH_uint64(data) (++(data))
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# define ATOMIC_STORE_1_TO_32BIT(data) (data) = 1 // TODO: del
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#endif
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# define DEF_ATOMIC_HELPER_MUT(x) pthread_mutex_t x
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# define INIT_ATOMIC_HELPER_MUT(x) pthread_mutex_init(&(x), NULL)
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# define DESTROY_ATOMIC_HELPER_MUT(x) pthread_mutex_destroy(&(x))
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# define PREFER_ATOMIC_INC(data) ((void) ++data)
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#endif
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#endif /* #ifndef INCLUDED_ATOMIC_H */
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