simplified worker thread handling

based on now working with detached threads. This is probably the biggest
patch in this series and with large bug potential.

4 files changed, 15 insertions, 171 deletions

diff --git a/runtime/wti.c b/runtime/wti.c
index 93c66028..f6a32c34 100644
--- a/runtime/wti.c
+++ b/runtime/wti.c
@@ -118,7 +118,7 @@ wtiSetState(wti_t *pThis, qWrkCmd_t tCmd, int bActiveOnly, int bLockMutex)
 	tCurrCmd = pThis->tCurrCmd;
 	/* all worker states must be followed sequentially, only termination can be set in any state */
 	if(   (bActiveOnly && (tCurrCmd < eWRKTHRD_RUN_CREATED))
-	   || (tCurrCmd > tCmd && !(tCmd == eWRKTHRD_TERMINATING || tCmd == eWRKTHRD_STOPPED))) {
+	   || (tCurrCmd > tCmd && !(tCmd == eWRKTHRD_STOPPED))) {
 		DBGPRINTF("%s: command %d can not be accepted in current %d processing state - ignored\n",
 			  wtiGetDbgHdr(pThis), tCmd, tCurrCmd);
 	} else {
@@ -126,25 +126,9 @@ wtiSetState(wti_t *pThis, qWrkCmd_t tCmd, int bActiveOnly, int bLockMutex)
 		/* we could replace this with a simple if, but we leave the switch in in case we need
 		 * to add something at a later stage. -- rgerhards, 2008-09-30
 		 */
-		switch(tCmd) {
-			case eWRKTHRD_TERMINATING:
-				/* TODO: re-enable meaningful debug msg! (via function callback?)
-				dbgprintf("%s: thread terminating with %d entries left in queue, %d workers running.\n",
-					  wtiGetDbgHdr(pThis->pQueue), pThis->pQueue->iQueueSize,
-					  pThis->pQueue->iCurNumWrkThrd);
-				*/
-				pthread_cond_signal(&pThis->condExitDone);
-				dbgprintf("%s: worker terminating\n", wtiGetDbgHdr(pThis));
-				break;
-			/* these cases just to satisfy the compiler, we do (yet) not act an them: */
-			case eWRKTHRD_RUNNING:
-			case eWRKTHRD_STOPPED:
-			case eWRKTHRD_RUN_CREATED:
-			case eWRKTHRD_RUN_INIT:
-			case eWRKTHRD_SHUTDOWN:
-			case eWRKTHRD_SHUTDOWN_IMMEDIATE:
-				/* DO NOTHING */
-				break;
+		if(tCmd == eWRKTHRD_STOPPED) {
+			dbgprintf("%s: worker almost stopped, assuming it has\n", wtiGetDbgHdr(pThis));
+			pThis->thrdID = 0; /* invalidate the thread ID so that we do not accidently find reused ones */
 		}
 		/* apply the new state */
 dbgprintf("worker terminator will write stateval %d\n", tCmd);
@@ -152,7 +136,6 @@ dbgprintf("worker terminator will write stateval %d\n", tCmd);
 		if(val != tCurrCmd) {
 			DBGPRINTF("wtiSetState PROBLEM, tCurrCmd %d overwritten with %d, wanted to set %d\n", tCurrCmd, val, tCmd);
 		}
-//dbgprintf("worker terminator has written stateval %d\n", tCmd);
 	}
 
 	END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
@@ -174,12 +157,11 @@ wtiCancelThrd(wti_t *pThis)
 
 	d_pthread_mutex_lock(&pThis->mut);
 
-	wtiProcessThrdChanges(pThis, MUTEX_ALREADY_LOCKED); /* process state change, so that we have current state vars */
-
-	if(pThis->tCurrCmd >= eWRKTHRD_TERMINATING) {
+	if(pThis->tCurrCmd != eWRKTHRD_STOPPED) {
 		dbgoprint((obj_t*) pThis, "canceling worker thread, curr stat %d\n", pThis->tCurrCmd);
 		pthread_cancel(pThis->thrdID);
-		wtiSetState(pThis, eWRKTHRD_TERMINATING, 0, MUTEX_ALREADY_LOCKED);
+		/* TODO: check: the following check should automatically be done by cancel cleanup handler! 2009-07-08 rgerhards */
+		wtiSetState(pThis, eWRKTHRD_STOPPED, 0, MUTEX_ALREADY_LOCKED);
 		ATOMIC_STORE_1_TO_INT(pThis->pWtp->bThrdStateChanged); /* indicate change, so harverster will be called */
 	}
 
@@ -192,24 +174,12 @@ wtiCancelThrd(wti_t *pThis)
 /* Destructor */
 BEGINobjDestruct(wti) /* be sure to specify the object type also in END and CODESTART macros! */
 CODESTARTobjDestruct(wti)
-	/* if we reach this point, we must make sure the associated worker has terminated. It is
-	 * the callers duty to make sure the worker already knows it shall terminate.
-	 * TODO: is it *really* the caller's duty? ...mmmhhhh.... smells bad... rgerhards, 2008-01-25
-	 */
-	wtiProcessThrdChanges(pThis, LOCK_MUTEX); /* process state change one last time */
-
-	d_pthread_mutex_lock(&pThis->mut);
-	if(wtiGetState(pThis, MUTEX_ALREADY_LOCKED) != eWRKTHRD_STOPPED) {
-		dbgprintf("%s: WARNING: worker %p shall be destructed but is still running (might be OK) - joining it\n",
+	if(Debug && wtiGetState(pThis, MUTEX_ALREADY_LOCKED) != eWRKTHRD_STOPPED) {
+		dbgprintf("%s: WARNING: worker %p shall be destructed but is still running (might be OK) - ignoring\n",
 			  wtiGetDbgHdr(pThis), pThis);
-		/* let's hope the caller actually instructed it to shutdown... */
-		pthread_cond_wait(&pThis->condExitDone, &pThis->mut);
-		wtiJoinThrd(pThis);
 	}
-	d_pthread_mutex_unlock(&pThis->mut);
 
 	/* actual destruction */
-	pthread_cond_destroy(&pThis->condExitDone);
 	pthread_mutex_destroy(&pThis->mut);
 
 	free(pThis->batch.pElem);
@@ -220,7 +190,6 @@ ENDobjDestruct(wti)
 /* Standard-Constructor for the wti object
  */
 BEGINobjConstruct(wti) /* be sure to specify the object type also in END macro! */
-	pthread_cond_init(&pThis->condExitDone, NULL);
 	pthread_mutex_init(&pThis->mut, NULL);
 ENDobjConstruct(wti)
 
@@ -250,66 +219,6 @@ finalize_it:
 }
 
 
-/* join a specific worker thread
- * we do not lock the mutex, because join will sync anyways...
- */
-rsRetVal
-wtiJoinThrd(wti_t *pThis)
-{
-	DEFiRet;
-
-	ISOBJ_TYPE_assert(pThis, wti);
-	dbgprintf("waiting for worker %s termination, current state %d\n", wtiGetDbgHdr(pThis), pThis->tCurrCmd);
-	if (pThis->thrdID == 0) {
-		dbgprintf("worker %s was already stopped\n", wtiGetDbgHdr(pThis));
-	} else {
-		//pthread_join(pThis->thrdID, NULL);
-		wtiSetState(pThis, eWRKTHRD_STOPPED, 0, MUTEX_ALREADY_LOCKED); /* back to virgin... */
-		pThis->thrdID = 0; /* invalidate the thread ID so that we do not accidently find reused ones */
-	dbgprintf("worker %s has stopped\n", wtiGetDbgHdr(pThis));
-	}   
-
-	RETiRet;
-}
-
-/* check if we had a worker thread changes and, if so, act
- * on it. At a minimum, terminated threads are harvested (joined).
- */
-rsRetVal
-wtiProcessThrdChanges(wti_t *pThis, int bLockMutex)
-{
-	DEFiRet;
-	DEFVARS_mutexProtection;
-
-	ISOBJ_TYPE_assert(pThis, wti);
-
-	BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, bLockMutex);
-	switch(pThis->tCurrCmd) {
-		case eWRKTHRD_TERMINATING:
-			/* we need to at least temporarily release the mutex, because otherwise
-			 * we may deadlock with the thread we intend to join (it aquires the mutex
-			 * during termination processing). -- rgerhards, 2008-02-26
-			 */
-			END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
-			iRet = wtiJoinThrd(pThis);
-			BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, bLockMutex);
-			break;
-		/* these cases just to satisfy the compiler, we do not act an them: */
-		case eWRKTHRD_STOPPED:
-		case eWRKTHRD_RUN_CREATED:
-		case eWRKTHRD_RUN_INIT:
-		case eWRKTHRD_RUNNING:
-		case eWRKTHRD_SHUTDOWN:
-		case eWRKTHRD_SHUTDOWN_IMMEDIATE:
-			/* DO NOTHING */
-			break;
-	}
-	END_MTX_PROTECTED_OPERATIONS(&pThis->mut);
-
-	RETiRet;
-}
-
-
 /* cancellation cleanup handler for queueWorker ()
  * Updates admin structure and frees ressources.
  * rgerhards, 2008-01-16
@@ -333,7 +242,7 @@ wtiWorkerCancelCleanup(void *arg)
 
 	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &iCancelStateSave);
 	d_pthread_mutex_lock(&pWtp->mut);
-	wtiSetState(pThis, eWRKTHRD_TERMINATING, 0, MUTEX_ALREADY_LOCKED);
+	wtiSetState(pThis, eWRKTHRD_STOPPED, 0, MUTEX_ALREADY_LOCKED);
 	/* TODO: sync access? I currently think it is NOT needed -- rgerhards, 2008-01-28 */
 	ATOMIC_STORE_1_TO_INT(pWtp->bThrdStateChanged); /* indicate change, so harverster will be called */
 
@@ -399,7 +308,6 @@ wtiWorker(wti_t *pThis)
 	/* now we have our identity, on to real processing */
 	while(1) { /* loop will be broken below - need to do mutex locks */
 		/* process any pending thread requests */
-	//	wtpProcessThrdChanges(pWtp);
 
 		if(pWtp->pfRateLimiter != NULL) { /* call rate-limiter, if defined */
 			pWtp->pfRateLimiter(pWtp->pUsr);
@@ -455,7 +363,7 @@ wtiWorker(wti_t *pThis)
 RUNLOG_STR("XXX: Worker shutdown");
 	pWtp->pfOnWorkerShutdown(pWtp->pUsr);
 
-	wtiSetState(pThis, eWRKTHRD_TERMINATING, 0, MUTEX_ALREADY_LOCKED);
+	wtiSetState(pThis, eWRKTHRD_STOPPED, 0, MUTEX_ALREADY_LOCKED);
 	ATOMIC_STORE_1_TO_INT(pWtp->bThrdStateChanged); /* indicate change, so harverster will be called */
 	d_pthread_mutex_unlock(&pThis->mut);
 	pthread_setcancelstate(iCancelStateSave, NULL);
diff --git a/runtime/wti.h b/runtime/wti.h
index 2acd3cf6..5b7e5baf 100644
--- a/runtime/wti.h
+++ b/runtime/wti.h
@@ -36,7 +36,7 @@ struct wti_s {
 	pthread_t thrdID;  /* thread ID */
 	qWrkCmd_t tCurrCmd; /* current command to be carried out by worker */
 	wtp_t *pWtp; /* my worker thread pool (important if only the work thread instance is passed! */
-	pthread_cond_t condExitDone; /* signaled when the thread exit is done (once per thread existance) */
+	//pthread_cond_t condExitDone; /* signaled when the thread exit is done (once per thread existance) */
 	pthread_mutex_t mut;
 	batch_t batch; /* pointer to an object array meaningful for current user pointer (e.g. queue pUsr data elemt) */
 	bool bShutdownRqtd;	/* shutdown for this thread requested? 0 - no , 1 - yes */
diff --git a/runtime/wtp.c b/runtime/wtp.c
index 59553984..b27ce9f0 100644
--- a/runtime/wtp.c
+++ b/runtime/wtp.c
@@ -142,8 +142,6 @@ finalize_it:
 BEGINobjDestruct(wtp) /* be sure to specify the object type also in END and CODESTART macros! */
 	int i;
 CODESTARTobjDestruct(wtp)
-	wtpProcessThrdChanges(pThis); /* process thread changes one last time */
-
 	/* destruct workers */
 	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i)
 		wtiDestruct(&pThis->pWrkr[i]);
@@ -190,51 +188,6 @@ wtpWakeupAllWrkr(wtp_t *pThis)
 }
 
 
-/* check if we had any worker thread changes and, if so, act
- * on them. At a minimum, terminated threads are harvested (joined).
- * This function MUST NEVER block on the queue mutex!
- */
-rsRetVal
-wtpProcessThrdChanges(wtp_t *pThis)
-{
-	DEFiRet;
-	int i;
-
-	ISOBJ_TYPE_assert(pThis, wtp);
-
-	if(pThis->bThrdStateChanged == 0)
-		FINALIZE;
-
-	if(d_pthread_mutex_trylock(&(pThis->mutThrdShutdwn)) != 0) {
-		/* another thread is already in the loop */
-		FINALIZE;
-	}
-
-	/* Note: there is a left-over potential race condition below:
-	 * pThis->bThrdStateChanged may be re-set by another thread while
-	 * we work on it and thus the loop may terminate too early. However,
-	 * there are no really bad effects from that so I perfer - for this
-	 * version - to live with the problem as is. Not a good idea to 
-	 * introduce that large change into the stable branch without very
-	 * good reason. -- rgerhards, 2009-04-02
-	 */
-	do {
-		/* reset the change marker */
-		ATOMIC_STORE_0_TO_INT(pThis->bThrdStateChanged);
-		/* go through all threads */
-		for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
-			wtiProcessThrdChanges(pThis->pWrkr[i], LOCK_MUTEX);
-		}
-	/* restart if another change occured while we were processing the changes */
-	} while(pThis->bThrdStateChanged != 0);
-
-	d_pthread_mutex_unlock(&(pThis->mutThrdShutdwn));
-
-finalize_it:
-	RETiRet;
-}
-
-
 /* Sent a specific state for the worker thread pool.
  * rgerhards, 2008-01-21
  */
@@ -299,12 +252,7 @@ wtpShutdownAll(wtp_t *pThis, wtpState_t tShutdownCmd, struct timespec *ptTimeout
 	wtpSetState(pThis, tShutdownCmd);
 	wtpWakeupAllWrkr(pThis);
 
-	/* see if we need to harvest (join) any terminated threads (even in timeout case,
-	 * some may have terminated...
-	 */
-	wtpProcessThrdChanges(pThis);
-		
-	/* and wait for their termination */
+	/* wait for worker thread termination */
 	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &iCancelStateSave);
 	d_pthread_mutex_lock(&pThis->mut);
 	pthread_cleanup_push(mutexCancelCleanup, &pThis->mut);
@@ -324,11 +272,6 @@ wtpShutdownAll(wtp_t *pThis, wtpState_t tShutdownCmd, struct timespec *ptTimeout
 	if(bTimedOut)
 		iRet = RS_RET_TIMED_OUT;
 	
-	/* see if we need to harvest (join) any terminated threads (even in timeout case,
-	 * some may have terminated...
-	 */
-	wtpProcessThrdChanges(pThis);
-
 	RETiRet;
 }
 #pragma GCC diagnostic warning "-Wempty-body"
@@ -369,9 +312,6 @@ wtpCancelAll(wtp_t *pThis)
 
 	ISOBJ_TYPE_assert(pThis, wtp);
 
-	/* process any pending thread requests so that we know who actually is still running */
-	wtpProcessThrdChanges(pThis);
-
 	/* go through all workers and cancel those that are active */
 	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
 		dbgprintf("%s: try canceling worker thread %d\n", wtpGetDbgHdr(pThis), i);
@@ -502,15 +442,11 @@ wtpStartWrkr(wtp_t *pThis, int bLockMutex)
 
 	ISOBJ_TYPE_assert(pThis, wtp);
 
-	wtpProcessThrdChanges(pThis);	// TODO: Performance: this causes a lot of FUTEX calls
-
 	BEGIN_MTX_PROTECTED_OPERATIONS(&pThis->mut, bLockMutex);
 
 	pThis->iCurNumWrkThrd++;
 
-	/* find free spot in thread table. If we find at least one worker that is in initialization,
-	 * we do NOT start a new one. Let's give the other one a chance, first.
-	 */
+	/* find free spot in thread table. */
 	for(i = 0 ; i < pThis->iNumWorkerThreads ; ++i) {
 		if(wtiGetState(pThis->pWrkr[i], LOCK_MUTEX) == eWRKTHRD_STOPPED) {
 			break;
diff --git a/runtime/wtp.h b/runtime/wtp.h
index ef61d7e6..03bc538f 100644
--- a/runtime/wtp.h
+++ b/runtime/wtp.h
@@ -30,7 +30,7 @@
 /* commands and states for worker threads. */
 typedef enum {
 	eWRKTHRD_STOPPED = 0,	/* worker thread is not running (either actually never ran or was shut down) */
-	eWRKTHRD_TERMINATING = 1,/* worker thread has shut down, but some finalzing is still needed */
+	//eWRKTHRD_TERMINATING = 1,/* worker thread has shut down, but some finalzing is still needed */
 	/* ALL active states MUST be numerically higher than eWRKTHRD_TERMINATED and NONE must be lower! */
 	eWRKTHRD_RUN_CREATED = 2,/* worker thread has been created, but not yet begun initialization (prob. not yet scheduled) */
 	eWRKTHRD_RUN_INIT = 3,	/* worker thread is initializing, but not yet fully running */