checkpoint

lib/isc/task.c

@@ -18,6 +18,11 @@
 
 #define FINISHED(m)	((m)->exiting && EMPTY((m)->tasks))
 
+#ifdef DEBUGTRACE
+#define XTRACE(m)	printf("%s %p\n", (m), pthread_self())
+#else
+#define XTRACE(m)
+#endif
 
 /***
  *** Tasks.
@@ -27,7 +32,7 @@ static void
 task_free(task_t task) {
 	task_manager_t manager = task->manager;
 
-	printf("free task\n");
+	XTRACE("free task");
 	REQUIRE(EMPTY(task->events));
 
 	LOCK(&manager->lock);
@@ -48,8 +53,10 @@ task_free(task_t task) {
 }
 
 boolean_t
-task_allocate(task_manager_t manager, event_action_t shutdown_action,
-	      u_int32_t quantum, task_t *taskp) {
+task_allocate(task_manager_t manager, void *arg,
+	      event_action_t shutdown_action, unsigned int quantum,
+	      task_t *taskp)
+{
 	task_t task;
 
 	REQUIRE(VALID_MANAGER(manager));
@@ -67,6 +74,7 @@ task_allocate(task_manager_t manager, event_action_t shutdown_action,
 	INIT_LIST(task->events);
 	task->quantum = quantum;
 	task->shutdown_pending = FALSE;
+	task->arg = arg;
 	task->shutdown_action = shutdown_action;
 	INIT_LINK(task, link);
 	INIT_LINK(task, ready_link);
@@ -103,7 +111,7 @@ task_detach(task_t *taskp) {
 	task_manager_t manager;
 	task_t task;
 
-	printf("task_detach\n");
+	XTRACE("task_detach");
 
 	REQUIRE(taskp != NULL);
 	task = *taskp;
@@ -112,7 +120,7 @@ task_detach(task_t *taskp) {
 	LOCK(&task->lock);
 	REQUIRE(task->references > 0);
 	task->references--;
-	if (task->state == task_state_zombie &&
+	if (task->state == task_state_shutdown &&
 	    task->references == 0) {
 		manager = task->manager;
 		INSIST(VALID_MANAGER(manager));
@@ -136,14 +144,14 @@ task_send_event(task_t task, generic_event_t event) {
 	REQUIRE(VALID_TASK(task));
 	REQUIRE(event != NULL);
 
-	printf("sending\n");
+	XTRACE("sending");
 	/*
 	 * We're trying hard to hold locks for as short a time as possible.
 	 * We're also trying to hold as few locks as possible.  This is why
 	 * some processing is deferred until after a lock is released.
 	 */
 	LOCK(&task->lock);
-	if (task->state != task_state_zombie && !task->shutdown_pending) {
+	if (task->state != task_state_shutdown && !task->shutdown_pending) {
 		if (task->state == task_state_idle) {
 			was_idle = TRUE;
 			INSIST(EMPTY(task->events));
@@ -157,7 +165,7 @@ task_send_event(task_t task, generic_event_t event) {
 	UNLOCK(&task->lock);
 
 	if (discard) {
-		mem_put(event->mctx, event, sizeof *event);
+		mem_put(event->mctx, event, event->size);
 		return (TRUE);
 	}
 
@@ -201,14 +209,14 @@ task_send_event(task_t task, generic_event_t event) {
 			BROADCAST(&manager->work_available);
 	}
 
-	printf("sent\n");
+	XTRACE("sent");
 	return (TRUE);
 }
 
 boolean_t
 task_shutdown(task_t task) {
 	boolean_t was_idle = FALSE;
-	boolean_t zombie = FALSE;
+	boolean_t discard = FALSE;
 
 	REQUIRE(VALID_TASK(task));
 
@@ -217,7 +225,7 @@ task_shutdown(task_t task) {
 	 */
 
 	LOCK(&task->lock);
-	if (task->state != task_state_zombie) {
+	if (task->state != task_state_shutdown && !task->shutdown_pending) {
 		if (task->state == task_state_idle) {
 			was_idle = TRUE;
 			INSIST(EMPTY(task->events));
@@ -227,10 +235,10 @@ task_shutdown(task_t task) {
 		       task->state == task_state_running);
 		task->shutdown_pending = TRUE;
 	} else
-		zombie = TRUE;
+		discard = TRUE;
 	UNLOCK(&task->lock);
 
-	if (zombie)
+	if (discard)
 		return (TRUE);
 
 	if (was_idle) {
@@ -262,9 +270,8 @@ void *task_manager_run(void *uap) {
 	task_manager_t manager = uap;
 	task_t task;
 	boolean_t no_workers = FALSE;
-	int spin = 0;
 
-	printf("start %p\n", pthread_self());
+	XTRACE("start");
 
 	REQUIRE(VALID_MANAGER(manager));
 
@@ -328,21 +335,22 @@ void *task_manager_run(void *uap) {
 		 * task lock.
 		 */
 		while (EMPTY(manager->ready_tasks) && !FINISHED(manager)) {
-			printf("wait %p\n", pthread_self());
+			XTRACE("wait");
 			WAIT(&manager->work_available, &manager->lock);
-			printf("awake %p\n", pthread_self());
+			XTRACE("awake");
 		}
-		printf("working %p\n", pthread_self());
+		XTRACE("working");
 		
 		task = HEAD(manager->ready_tasks);
 		if (task != NULL) {
-			u_int32_t dispatch_count = 0;
+			unsigned int dispatch_count = 0;
 			boolean_t done = FALSE;
 			boolean_t requeue = FALSE;
 			boolean_t wants_shutdown;
 			boolean_t free_task = FALSE;
-			generic_event_t	event;
+			void *arg;
 			event_action_t action;
+			generic_event_t	event;
 			event_list_t remaining_events;
 			boolean_t discard_remaining = FALSE;
 
@@ -370,30 +378,50 @@ void *task_manager_run(void *uap) {
 					action = event->action;
 					DEQUEUE(task->events, event, link);
 				}
+				arg = task->arg;
 				UNLOCK(&task->lock);
 
-				printf("dispatch %p\n", pthread_self());
 				/*
 				 * Execute the event action.
 				 */
+				XTRACE("execute action");
 				if (action != NULL)
-					wants_shutdown = (*action)(event);
+					wants_shutdown = (*action)(task,
+								   arg,
+								   event);
 				else
 					wants_shutdown = FALSE;
+				dispatch_count++;
 
 				/*
 				 * If this wasn't a shutdown event, we
 				 * need to free it.
+				 *
+				 * Also, if we've delivered the shutdown
+				 * event to the task, then we are going
+				 * to shut it down no matter what the task
+				 * callback returned.
 				 */
 				if (event != NULL)
 					mem_put(event->mctx, event,
-						sizeof *event);
+						event->size);
 				else
 					wants_shutdown = TRUE;
 
 				LOCK(&task->lock);
 				if (wants_shutdown) {
-					printf("wants shutdown\n");
+					/*
+					 * The task has either had the
+					 * shutdown event sent to it, or
+					 * an event action requested shutdown.
+					 *
+					 * Since no more events can be
+					 * delivered to the task, we purge
+					 * any remaining events (but defer
+					 * freeing them until we've released
+					 * the lock).
+					 */
+					XTRACE("wants shutdown");
 					if (!EMPTY(task->events)) {
 						remaining_events =
 							task->events;
@@ -402,10 +430,14 @@ void *task_manager_run(void *uap) {
 					}
 					if (task->references == 0)
 						free_task = TRUE;
-					task->state = task_state_zombie;
+					task->state = task_state_shutdown;
 					done = TRUE;
 				} else if (EMPTY(task->events) &&
 					   !task->shutdown_pending) {
+					/*
+					 * Nothing else to do for this task.
+					 * Put it to sleep.
+					 */
 					task->state = task_state_idle;
 					done = TRUE;
 				} else if (dispatch_count >= task->quantum) {
@@ -434,7 +466,7 @@ void *task_manager_run(void *uap) {
 				     event = next_event) {
 					next_event = NEXT(event, link);
 					mem_put(event->mctx, event,
-						sizeof *event);
+						event->size);
 				}
 			}
 
@@ -476,7 +508,7 @@ void *task_manager_run(void *uap) {
 	if (no_workers)
 		BROADCAST(&manager->no_workers);
 
-	printf("exit %p\n", pthread_self());
+	XTRACE("exit");
 
 	return (NULL);	
 }
@@ -490,11 +522,11 @@ manager_free(task_manager_t manager) {
 	mem_put(manager->mctx, manager, sizeof *manager);
 }
 
-u_int32_t
-task_manager_create(mem_context_t mctx, int workers, int default_quantum,
-		    task_manager_t *managerp) {
-	int i;
-	u_int32_t started = 0;
+unsigned int
+task_manager_create(mem_context_t mctx, unsigned int workers, 
+		    unsigned int default_quantum, task_manager_t *managerp)
+{
+	unsigned int i, started = 0;
 	task_manager_t manager;
 	os_thread_t thread;
 
@@ -546,7 +578,7 @@ task_manager_destroy(task_manager_t *managerp) {
 	manager = *managerp;
 	REQUIRE(VALID_MANAGER(manager));
 
-	printf("task_manager_destroy %p\n", pthread_self());
+	XTRACE("task_manager_destroy");
 	/*
 	 * Only one non-worker thread may ever call this routine.
 	 * If a worker thread wants to initiate shutdown of the