Merge branch 'helgrind' into perf

Conflicts:

	ChangeLog

ChangeLog

@@ -13,6 +13,13 @@ Version 3.21.5  [DEVEL] (rgerhards), 2008-09-??
   local host as it knows itself.
 - doc bugfix: queue doc had wrong parameter name for setting controlling
   worker thread shutdown period
+- re-enabled gcc builtin atomic operations and added a proper
+  ./configure check
+- bugfix: potential race condition when adding messages to queue
+  There was a wrong order of mutex lock operations. It is hard to
+  believe that really caused problems, but in theory it could and with
+  threading we often see that theory becomes practice if something is only
+  used long enough on a fast enough machine with enough CPUs ;)
 ---------------------------------------------------------------------------
 Version 3.21.4  [DEVEL] (rgerhards), 2008-09-04
 - removed compile time fixed message size limit (was 2K), limit can now

configure.ac

@@ -107,6 +107,56 @@ AC_TRY_COMPILE([
 	AC_MSG_RESULT(no; defined as 64)
 )
 
+# check for availability of atomic operations
+# rgerhards, 2008-09-18, added based on 
+# http://svn.apache.org/repos/asf/apr/apr/trunk/configure.in
+
+AC_CACHE_CHECK([whether the compiler provides atomic builtins], [ap_cv_atomic_builtins],
+[AC_TRY_RUN([
+int main()
+{
+    unsigned long val = 1010, tmp, *mem = &val;
+
+    if (__sync_fetch_and_add(&val, 1010) != 1010 || val != 2020)
+        return 1;
+
+    tmp = val;
+
+    if (__sync_fetch_and_sub(mem, 1010) != tmp || val != 1010)
+        return 1;
+
+    if (__sync_sub_and_fetch(&val, 1010) != 0 || val != 0)
+        return 1;
+
+    tmp = 3030;
+
+    if (__sync_val_compare_and_swap(mem, 0, tmp) != 0 || val != tmp)
+        return 1;
+
+    if (__sync_lock_test_and_set(&val, 4040) != 3030)
+        return 1;
+
+    mem = &tmp;
+
+    if (__sync_val_compare_and_swap(&mem, &tmp, &val) != &tmp)
+        return 1;
+
+    __sync_synchronize();
+
+    if (mem != &val)
+        return 1;
+
+    return 0;
+}], [ap_cv_atomic_builtins=yes], [ap_cv_atomic_builtins=no], [ap_cv_atomic_builtins=no])])
+
+if test "$ap_cv_atomic_builtins" = "yes"; then
+    AC_DEFINE(HAVE_ATOMIC_BUILTINS, 1, [Define if compiler provides atomic builtins])
+fi
+
+
+
+
+
 # Large file support
 AC_ARG_ENABLE(largefile,
         [AS_HELP_STRING([--enable-largefile],[Enable large file support @<:@default=yes@:>@])],

runtime/atomic.h

@@ -1,6 +1,6 @@
 /* This header supplies atomic operations. So far, we rely on GCC's
- * atomic builtins. I have no idea if we can check them via autotools,
- * but I am making the necessary provisioning to live without them if
+ * 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.
@@ -36,16 +36,20 @@
 #ifndef INCLUDED_ATOMIC_H
 #define INCLUDED_ATOMIC_H
 
-/* set the following to 1 if we have atomic operations (and #undef it otherwise) */
-/* #define DO_HAVE_ATOMICS 1 */
 /* 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
  */
-/* make sure they are not used!
-#define ATOMIC_INC(data) ((void) __sync_fetch_and_add(&data, 1))
-#define ATOMIC_DEC_AND_FETCH(data) __sync_sub_and_fetch(&data, 1)
-*/
-#define ATOMIC_INC(data) (++(data))
+#ifdef HAVE_ATOMIC_BUILTINS
+#	define ATOMIC_INC(data) ((void) __sync_fetch_and_add(&(data), 1))
+#	define ATOMIC_DEC_AND_FETCH(data) __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)
+#else
+#	warning "atomic builtins not available, using nul operations"
+#	define ATOMIC_INC(data) (++(data))
+#	define ATOMIC_FETCH_32BIT(data) (data)
+#	define ATOMIC_STORE_1_TO_32BIT(data) (data) = 1
+#endif
 
 #endif /* #ifndef INCLUDED_ATOMIC_H */

runtime/debug.c

@@ -481,7 +481,23 @@ static inline void dbgMutexUnlockLog(pthread_mutex_t *pmut, dbgFuncDB_t *pFuncDB
 
 	pthread_mutex_lock(&mutMutLog);
 	pLog = dbgMutLogFindSpecific(pmut, MUTOP_LOCK, NULL);
+#if 0 /* toggle for testing */
 	assert(pLog != NULL);
+#else
+/* the change below seems not to work - the problem seems to be a real race... I keep this code in just in case
+ * I need to re-use it. It should be removed once we are finished analyzing this problem. -- rgerhards, 2008-09-17
+ */
+if(pLog == NULL) {
+	/* this may happen due to some races. We do not try to avoid
+	 * this, as it would complicate the "real" code. This is not justified
+	 * just to keep the debug info system up. -- rgerhards, 2008-09-17
+	 */
+	pthread_mutex_unlock(&mutMutLog);
+	dbgprintf("%s:%d:%s: mutex %p UNlocked [but we did not yet know this mutex!]\n",
+		  pFuncDB->file, unlockLn, pFuncDB->func, (void*)pmut);
+	return; /* if we don't know it yet, we can not clean up... */
+}
+#endif
 
 	/* we found the last lock entry. We now need to see from which FuncDB we need to
 	 * remove it. This is recorded inside the mutex log entry.

runtime/debug.h

@@ -130,7 +130,8 @@ void dbgPrintAllDebugInfo(void);
 
 
 /* debug aides */
-#ifdef RTINST
+//#ifdef RTINST
+#if 0 // temporarily removed for helgrind
 #define d_pthread_mutex_lock(x)      dbgMutexLock(x, pdbgFuncDB, __LINE__, dbgCALLStaCK_POP_POINT )
 #define d_pthread_mutex_unlock(x)    dbgMutexUnlock(x, pdbgFuncDB, __LINE__, dbgCALLStaCK_POP_POINT )
 #define d_pthread_cond_wait(cond, mut)   dbgCondWait(cond, mut, pdbgFuncDB, __LINE__, dbgCALLStaCK_POP_POINT )

runtime/queue.c

@@ -2171,17 +2171,17 @@ queueEnqObj(queue_t *pThis, flowControl_t flowCtlType, void *pUsr)
 
 finalize_it:
 	if(pThis->qType != QUEUETYPE_DIRECT) {
-		d_pthread_mutex_unlock(pThis->mut);
+		/* make sure at least one worker is running. */
+		if(pThis->qType != QUEUETYPE_DIRECT) {
+			queueAdviseMaxWorkers(pThis);
+		}
+		/* and release the mutex */
 		i = pthread_cond_signal(&pThis->notEmpty);
+		d_pthread_mutex_unlock(pThis->mut);
 		dbgoprint((obj_t*) pThis, "EnqueueMsg signaled condition (%d)\n", i);
 		pthread_setcancelstate(iCancelStateSave, NULL);
 	}
 
-	/* make sure at least one worker is running. */
-	if(pThis->qType != QUEUETYPE_DIRECT) {
-		queueAdviseMaxWorkers(pThis);
-	}
-
 	RETiRet;
 }
 

tools/syslogd.c

@@ -2830,9 +2830,8 @@ static rsRetVal mainThread()
 
 	CHKiRet(init());
 
-	if(Debug) {
+	if(Debug && debugging_on) {
 		dbgprintf("Debugging enabled, SIGUSR1 to turn off debugging.\n");
-		debugging_on = 1;
 	}
 	/* Send a signal to the parent so it can terminate.
 	 */
@@ -3080,9 +3079,9 @@ doGlblProcessInit(void)
 			fputs(" Already running.\n", stderr);
 			exit(1); /* "good" exit, done if syslogd is already running */
 		}
-	}
-	else
+	} else {
 		debugging_on = 1;
+	}
 
 	/* tuck my process id away */
 	dbgprintf("Writing pidfile %s.\n", PidFile);