bugfix: problems with atomic operations emulation

replaced atomic operation emulation with new code. The previous code
seemed to have some issue and also limited concurrency severely. The
whole atomic operation emulation has been rewritten.

1 files changed, 71 insertions, 129 deletions

diff --git a/runtime/atomic.h b/runtime/atomic.h
index 271e825e..fc3e0b2d 100644
--- a/runtime/atomic.h
+++ b/runtime/atomic.h
@@ -39,134 +39,29 @@
  * They simply came in too late. -- rgerhards, 2008-04-02
  */
 #ifdef HAVE_ATOMIC_BUILTINS
-#	define ATOMIC_INC(data) ((void) __sync_fetch_and_add(&(data), 1))
+#	define ATOMIC_INC(data, phlpmut) ((void) __sync_fetch_and_add(data, 1))
 #	define ATOMIC_INC_AND_FETCH(data) __sync_fetch_and_add(&(data), 1)
-#	define ATOMIC_DEC(data) ((void) __sync_sub_and_fetch(&(data), 1))
-#	define ATOMIC_DEC_AND_FETCH(data) __sync_sub_and_fetch(&(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) ((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) __sync_fetch_and_and(&(data), 0)
-#	define ATOMIC_STORE_1_TO_INT(data) __sync_fetch_and_or(&(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) __sync_bool_compare_and_swap(&(data), (oldVal), (newVal));
-#	define ATOMIC_CAS_VAL(data, oldVal, newVal) __sync_val_compare_and_swap(&(data), (oldVal), (newVal));
-#else
-#ifdef HAVE_SEMAPHORE_H
-	/* we use POSIX semaphores instead */
-
-#include "rsyslog.h"
-#include <semaphore.h>
-
-extern sem_t atomicSem;
-rsRetVal atomicSemInit(void);
-void atomicSemExit(void);
-
-#if HAVE_TYPEOF
-#define my_typeof(x) typeof(x)
-#else /* sorry, can't determine types, using 'int' */
-#define my_typeof(x) int
-#endif
-
-#	define ATOMIC_SUB(data, val) \
-({ \
-	my_typeof(data) tmp; \
-	sem_wait(&atomicSem); \
-	tmp = data; \
-	data -= val; \
-	sem_post(&atomicSem); \
-	tmp; \
-})
-
-#	define ATOMIC_ADD(data, val) \
-({ \
-	my_typeof(data) tmp; \
-	sem_wait(&atomicSem); \
-	tmp = data; \
-	data += val; \
-	sem_post(&atomicSem); \
-	tmp; \
-})
-
-#	define ATOMIC_INC_AND_FETCH(data) \
-({ \
-	my_typeof(data) tmp; \
-	sem_wait(&atomicSem); \
-	tmp = data; \
-	data += 1; \
-	sem_post(&atomicSem); \
-	tmp; \
-})
-
-#	define ATOMIC_INC(data) ((void) ATOMIC_INC_AND_FETCH(data))
-
-#	define ATOMIC_DEC_AND_FETCH(data) \
-({ \
-	sem_wait(&atomicSem); \
-	data -= 1; \
-	sem_post(&atomicSem); \
-	data; \
-})
+#	define ATOMIC_CAS_VAL(data, oldVal, newVal, phlpmut) __sync_val_compare_and_swap(data, (oldVal), (newVal));
 
-#	define ATOMIC_DEC(data) ((void) ATOMIC_DEC_AND_FETCH(data))
+	/* 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) 
 
-#	define ATOMIC_FETCH_32BIT(data) ((unsigned) ATOMIC_ADD((data), 0xffffffff))
-
-#	define ATOMIC_STORE_1_TO_32BIT(data) \
-({ \
-	my_typeof(data) tmp; \
-	sem_wait(&atomicSem); \
-	tmp = data; \
-	data = 1; \
-	sem_post(&atomicSem); \
-	tmp; \
-})
-
-#	define ATOMIC_STORE_0_TO_INT(data) \
-({ \
-	my_typeof(data) tmp; \
-	sem_wait(&atomicSem); \
-	tmp = data; \
-	data = 0; \
-	sem_post(&atomicSem); \
-	tmp; \
-})
-
-#	define ATOMIC_STORE_1_TO_INT(data) \
-({ \
-	my_typeof(data) tmp; \
-	sem_wait(&atomicSem); \
-	tmp = data; \
-	data = 1; \
-	sem_post(&atomicSem); \
-	tmp; \
-})
-
-#	define ATOMIC_CAS(data, oldVal, newVal) \
-({ \
-	int ret; \
-	sem_wait(&atomicSem); \
-	if(data != oldVal) ret = 0; \
-	else \
-	{ \
-		data = newVal; \
-		ret = 1; \
-	} \
-	sem_post(&atomicSem); \
-	ret; \
-})
-
-#	define ATOMIC_CAS_VAL(data, oldVal, newVal) \
-({ \
-	sem_wait(&atomicSem); \
-	if(data == oldVal) \
-	{ \
-		data = newVal; \
-	} \
-	sem_post(&atomicSem); \
-	data; \
-})
-
-#else /* not HAVE_SEMAPHORE_H */
+	/* 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
@@ -174,16 +69,63 @@ void atomicSemExit(void);
 	 * 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_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_DEC_AND_FETCH(int *data, pthread_mutex_t *phlpmut) {
+		int val;
+		pthread_mutex_lock(phlpmut);
+		val = --(*data);
+		pthread_mutex_unlock(phlpmut);
+		return(val);
+	}
+#if 0
 #	warning "atomic builtins not available, using nul operations - rsyslogd will probably be racy!"
-#	define ATOMIC_INC(data) (++(data))
-#	define ATOMIC_DEC(data) (--(data))
-#	define ATOMIC_DEC_AND_FETCH(data) (--(data))
-#	define ATOMIC_FETCH_32BIT(data) (data)
-#	define ATOMIC_STORE_1_TO_32BIT(data) (data) = 1
-#	define ATOMIC_STORE_1_TO_INT(data) (data) = 1
-#	define ATOMIC_STORE_0_TO_INT(data) (data) = 0
-#	define ATOMIC_CAS_VAL(data, oldVal, newVal) (data) = (newVal)
+#	define ATOMIC_INC_AND_FETCH(data) (++(data))
+#	define ATOMIC_FETCH_32BIT(data) (data) // TODO: del
+#	define ATOMIC_STORE_1_TO_32BIT(data) (data) = 1 // TODO: del
 #endif
+#	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_init(&(x), NULL)
+
+#	define PREFER_ATOMIC_INC(data) ((void) ++data)
+
 #endif
 
 #endif /* #ifndef INCLUDED_ATOMIC_H */