/* * Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC") * Copyright (C) 1998-2002 Internet Software Consortium. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR * PERFORMANCE OF THIS SOFTWARE. */ /* $Id: task.c,v 1.85.2.5 2004/03/09 06:11:52 marka Exp $ */ /* * Principal Author: Bob Halley */ /* * XXXRTH Need to document the states a task can be in, and the rules * for changing states. */ #include #include #include #include #include #include #include #include #include #include #include #ifndef ISC_PLATFORM_USETHREADS #include "task_p.h" #endif /* ISC_PLATFORM_USETHREADS */ #define ISC_TASK_NAMES 1 #ifdef ISC_TASK_TRACE #define XTRACE(m) fprintf(stderr, "task %p thread %lu: %s\n", \ task, isc_thread_self(), (m)) #define XTTRACE(t, m) fprintf(stderr, "task %p thread %lu: %s\n", \ (t), isc_thread_self(), (m)) #define XTHREADTRACE(m) fprintf(stderr, "thread %lu: %s\n", \ isc_thread_self(), (m)) #else #define XTRACE(m) #define XTTRACE(t, m) #define XTHREADTRACE(m) #endif /*** *** Types. ***/ typedef enum { task_state_idle, task_state_ready, task_state_running, task_state_done } task_state_t; #define TASK_MAGIC ISC_MAGIC('T', 'A', 'S', 'K') #define VALID_TASK(t) ISC_MAGIC_VALID(t, TASK_MAGIC) struct isc_task { /* Not locked. */ unsigned int magic; isc_taskmgr_t * manager; isc_mutex_t lock; /* Locked by task lock. */ task_state_t state; unsigned int references; isc_eventlist_t events; isc_eventlist_t on_shutdown; unsigned int quantum; unsigned int flags; #ifdef ISC_TASK_NAMES char name[16]; void * tag; #endif /* Locked by task manager lock. */ LINK(isc_task_t) link; LINK(isc_task_t) ready_link; }; #define TASK_F_SHUTTINGDOWN 0x01 #define TASK_SHUTTINGDOWN(t) (((t)->flags & TASK_F_SHUTTINGDOWN) \ != 0) #define TASK_MANAGER_MAGIC ISC_MAGIC('T', 'S', 'K', 'M') #define VALID_MANAGER(m) ISC_MAGIC_VALID(m, TASK_MANAGER_MAGIC) struct isc_taskmgr { /* Not locked. */ unsigned int magic; isc_mem_t * mctx; isc_mutex_t lock; unsigned int workers; #ifdef ISC_PLATFORM_USETHREADS isc_thread_t * threads; #endif /* ISC_PLATFORM_USETHREADS */ /* Locked by task manager lock. */ unsigned int default_quantum; LIST(isc_task_t) tasks; isc_tasklist_t ready_tasks; #ifdef ISC_PLATFORM_USETHREADS isc_condition_t work_available; isc_condition_t exclusive_granted; #endif /* ISC_PLATFORM_USETHREADS */ unsigned int tasks_running; isc_boolean_t exclusive_requested; isc_boolean_t exiting; #ifndef ISC_PLATFORM_USETHREADS unsigned int refs; #endif /* ISC_PLATFORM_USETHREADS */ }; #define DEFAULT_TASKMGR_QUANTUM 10 #define DEFAULT_DEFAULT_QUANTUM 5 #define FINISHED(m) ((m)->exiting && EMPTY((m)->tasks)) #ifndef ISC_PLATFORM_USETHREADS static isc_taskmgr_t *taskmgr = NULL; #endif /* ISC_PLATFORM_USETHREADS */ /*** *** Tasks. ***/ static void task_finished(isc_task_t *task) { isc_taskmgr_t *manager = task->manager; REQUIRE(EMPTY(task->events)); REQUIRE(EMPTY(task->on_shutdown)); REQUIRE(task->references == 0); REQUIRE(task->state == task_state_done); XTRACE("task_finished"); LOCK(&manager->lock); UNLINK(manager->tasks, task, link); #ifdef ISC_PLATFORM_USETHREADS if (FINISHED(manager)) { /* * All tasks have completed and the * task manager is exiting. Wake up * any idle worker threads so they * can exit. */ BROADCAST(&manager->work_available); } #endif /* ISC_PLATFORM_USETHREADS */ UNLOCK(&manager->lock); DESTROYLOCK(&task->lock); task->magic = 0; isc_mem_put(manager->mctx, task, sizeof *task); } isc_result_t isc_task_create(isc_taskmgr_t *manager, unsigned int quantum, isc_task_t **taskp) { isc_task_t *task; isc_boolean_t exiting; REQUIRE(VALID_MANAGER(manager)); REQUIRE(taskp != NULL && *taskp == NULL); task = isc_mem_get(manager->mctx, sizeof *task); if (task == NULL) return (ISC_R_NOMEMORY); XTRACE("isc_task_create"); task->manager = manager; if (isc_mutex_init(&task->lock) != ISC_R_SUCCESS) { isc_mem_put(manager->mctx, task, sizeof *task); UNEXPECTED_ERROR(__FILE__, __LINE__, "isc_mutex_init() %s", isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_FAILED, "failed")); return (ISC_R_UNEXPECTED); } task->state = task_state_idle; task->references = 1; INIT_LIST(task->events); INIT_LIST(task->on_shutdown); task->quantum = quantum; task->flags = 0; #ifdef ISC_TASK_NAMES memset(task->name, 0, sizeof task->name); task->tag = NULL; #endif INIT_LINK(task, link); INIT_LINK(task, ready_link); exiting = ISC_FALSE; LOCK(&manager->lock); if (!manager->exiting) { if (task->quantum == 0) task->quantum = manager->default_quantum; APPEND(manager->tasks, task, link); } else exiting = ISC_TRUE; UNLOCK(&manager->lock); if (exiting) { DESTROYLOCK(&task->lock); isc_mem_put(manager->mctx, task, sizeof *task); return (ISC_R_SHUTTINGDOWN); } task->magic = TASK_MAGIC; *taskp = task; return (ISC_R_SUCCESS); } void isc_task_attach(isc_task_t *source, isc_task_t **targetp) { /* * Attach *targetp to source. */ REQUIRE(VALID_TASK(source)); REQUIRE(targetp != NULL && *targetp == NULL); XTTRACE(source, "isc_task_attach"); LOCK(&source->lock); source->references++; UNLOCK(&source->lock); *targetp = source; } static inline isc_boolean_t task_shutdown(isc_task_t *task) { isc_boolean_t was_idle = ISC_FALSE; isc_event_t *event, *prev; /* * Caller must be holding the task's lock. */ XTRACE("task_shutdown"); if (! TASK_SHUTTINGDOWN(task)) { XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_SHUTTINGDOWN, "shutting down")); task->flags |= TASK_F_SHUTTINGDOWN; if (task->state == task_state_idle) { INSIST(EMPTY(task->events)); task->state = task_state_ready; was_idle = ISC_TRUE; } INSIST(task->state == task_state_ready || task->state == task_state_running); /* * Note that we post shutdown events LIFO. */ for (event = TAIL(task->on_shutdown); event != NULL; event = prev) { prev = PREV(event, ev_link); DEQUEUE(task->on_shutdown, event, ev_link); ENQUEUE(task->events, event, ev_link); } } return (was_idle); } static inline void task_ready(isc_task_t *task) { isc_taskmgr_t *manager = task->manager; REQUIRE(VALID_MANAGER(manager)); REQUIRE(task->state == task_state_ready); XTRACE("task_ready"); LOCK(&manager->lock); ENQUEUE(manager->ready_tasks, task, ready_link); #ifdef ISC_PLATFORM_USETHREADS SIGNAL(&manager->work_available); #endif /* ISC_PLATFORM_USETHREADS */ UNLOCK(&manager->lock); } static inline isc_boolean_t task_detach(isc_task_t *task) { /* * Caller must be holding the task lock. */ REQUIRE(task->references > 0); XTRACE("detach"); task->references--; if (task->references == 0 && task->state == task_state_idle) { INSIST(EMPTY(task->events)); /* * There are no references to this task, and no * pending events. We could try to optimize and * either initiate shutdown or clean up the task, * depending on its state, but it's easier to just * make the task ready and allow run() or the event * loop to deal with shutting down and termination. */ task->state = task_state_ready; return (ISC_TRUE); } return (ISC_FALSE); } void isc_task_detach(isc_task_t **taskp) { isc_task_t *task; isc_boolean_t was_idle; /* * Detach *taskp from its task. */ REQUIRE(taskp != NULL); task = *taskp; REQUIRE(VALID_TASK(task)); XTRACE("isc_task_detach"); LOCK(&task->lock); was_idle = task_detach(task); UNLOCK(&task->lock); if (was_idle) task_ready(task); *taskp = NULL; } static inline isc_boolean_t task_send(isc_task_t *task, isc_event_t **eventp) { isc_boolean_t was_idle = ISC_FALSE; isc_event_t *event; /* * Caller must be holding the task lock. */ REQUIRE(eventp != NULL); event = *eventp; REQUIRE(event != NULL); REQUIRE(event->ev_type > 0); REQUIRE(task->state != task_state_done); XTRACE("task_send"); if (task->state == task_state_idle) { was_idle = ISC_TRUE; INSIST(EMPTY(task->events)); task->state = task_state_ready; } INSIST(task->state == task_state_ready || task->state == task_state_running); ENQUEUE(task->events, event, ev_link); *eventp = NULL; return (was_idle); } void isc_task_send(isc_task_t *task, isc_event_t **eventp) { isc_boolean_t was_idle; /* * Send '*event' to 'task'. */ REQUIRE(VALID_TASK(task)); XTRACE("isc_task_send"); /* * 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 the lock is released. */ LOCK(&task->lock); was_idle = task_send(task, eventp); UNLOCK(&task->lock); if (was_idle) { /* * We need to add this task to the ready queue. * * We've waited until now to do it because making a task * ready requires locking the manager. If we tried to do * this while holding the task lock, we could deadlock. * * We've changed the state to ready, so no one else will * be trying to add this task to the ready queue. The * only way to leave the ready state is by executing the * task. It thus doesn't matter if events are added, * removed, or a shutdown is started in the interval * between the time we released the task lock, and the time * we add the task to the ready queue. */ task_ready(task); } } void isc_task_sendanddetach(isc_task_t **taskp, isc_event_t **eventp) { isc_boolean_t idle1, idle2; isc_task_t *task; /* * Send '*event' to '*taskp' and then detach '*taskp' from its * task. */ REQUIRE(taskp != NULL); task = *taskp; REQUIRE(VALID_TASK(task)); XTRACE("isc_task_sendanddetach"); LOCK(&task->lock); idle1 = task_send(task, eventp); idle2 = task_detach(task); UNLOCK(&task->lock); /* * If idle1, then idle2 shouldn't be true as well since we're holding * the task lock, and thus the task cannot switch from ready back to * idle. */ INSIST(!(idle1 && idle2)); if (idle1 || idle2) task_ready(task); *taskp = NULL; } #define PURGE_OK(event) (((event)->ev_attributes & ISC_EVENTATTR_NOPURGE) == 0) static unsigned int dequeue_events(isc_task_t *task, void *sender, isc_eventtype_t first, isc_eventtype_t last, void *tag, isc_eventlist_t *events, isc_boolean_t purging) { isc_event_t *event, *next_event; unsigned int count = 0; REQUIRE(VALID_TASK(task)); REQUIRE(last >= first); XTRACE("dequeue_events"); /* * Events matching 'sender', whose type is >= first and <= last, and * whose tag is 'tag' will be dequeued. If 'purging', matching events * which are marked as unpurgable will not be dequeued. * * sender == NULL means "any sender", and tag == NULL means "any tag". */ LOCK(&task->lock); for (event = HEAD(task->events); event != NULL; event = next_event) { next_event = NEXT(event, ev_link); if (event->ev_type >= first && event->ev_type <= last && (sender == NULL || event->ev_sender == sender) && (tag == NULL || event->ev_tag == tag) && (!purging || PURGE_OK(event))) { DEQUEUE(task->events, event, ev_link); ENQUEUE(*events, event, ev_link); count++; } } UNLOCK(&task->lock); return (count); } unsigned int isc_task_purgerange(isc_task_t *task, void *sender, isc_eventtype_t first, isc_eventtype_t last, void *tag) { unsigned int count; isc_eventlist_t events; isc_event_t *event, *next_event; /* * Purge events from a task's event queue. */ XTRACE("isc_task_purgerange"); ISC_LIST_INIT(events); count = dequeue_events(task, sender, first, last, tag, &events, ISC_TRUE); for (event = HEAD(events); event != NULL; event = next_event) { next_event = NEXT(event, ev_link); isc_event_free(&event); } /* * Note that purging never changes the state of the task. */ return (count); } unsigned int isc_task_purge(isc_task_t *task, void *sender, isc_eventtype_t type, void *tag) { /* * Purge events from a task's event queue. */ XTRACE("isc_task_purge"); return (isc_task_purgerange(task, sender, type, type, tag)); } isc_boolean_t isc_task_purgeevent(isc_task_t *task, isc_event_t *event) { isc_event_t *curr_event, *next_event; /* * Purge 'event' from a task's event queue. * * XXXRTH: WARNING: This method may be removed before beta. */ REQUIRE(VALID_TASK(task)); /* * If 'event' is on the task's event queue, it will be purged, * unless it is marked as unpurgeable. 'event' does not have to be * on the task's event queue; in fact, it can even be an invalid * pointer. Purging only occurs if the event is actually on the task's * event queue. * * Purging never changes the state of the task. */ LOCK(&task->lock); for (curr_event = HEAD(task->events); curr_event != NULL; curr_event = next_event) { next_event = NEXT(curr_event, ev_link); if (curr_event == event && PURGE_OK(event)) { DEQUEUE(task->events, curr_event, ev_link); break; } } UNLOCK(&task->lock); if (curr_event == NULL) return (ISC_FALSE); isc_event_free(&curr_event); return (ISC_TRUE); } unsigned int isc_task_unsendrange(isc_task_t *task, void *sender, isc_eventtype_t first, isc_eventtype_t last, void *tag, isc_eventlist_t *events) { /* * Remove events from a task's event queue. */ XTRACE("isc_task_unsendrange"); return (dequeue_events(task, sender, first, last, tag, events, ISC_FALSE)); } unsigned int isc_task_unsend(isc_task_t *task, void *sender, isc_eventtype_t type, void *tag, isc_eventlist_t *events) { /* * Remove events from a task's event queue. */ XTRACE("isc_task_unsend"); return (dequeue_events(task, sender, type, type, tag, events, ISC_FALSE)); } isc_result_t isc_task_onshutdown(isc_task_t *task, isc_taskaction_t action, const void *arg) { isc_boolean_t disallowed = ISC_FALSE; isc_result_t result = ISC_R_SUCCESS; isc_event_t *event; /* * Send a shutdown event with action 'action' and argument 'arg' when * 'task' is shutdown. */ REQUIRE(VALID_TASK(task)); REQUIRE(action != NULL); event = isc_event_allocate(task->manager->mctx, NULL, ISC_TASKEVENT_SHUTDOWN, action, arg, sizeof *event); if (event == NULL) return (ISC_R_NOMEMORY); LOCK(&task->lock); if (TASK_SHUTTINGDOWN(task)) { disallowed = ISC_TRUE; result = ISC_R_SHUTTINGDOWN; } else ENQUEUE(task->on_shutdown, event, ev_link); UNLOCK(&task->lock); if (disallowed) isc_mem_put(task->manager->mctx, event, sizeof *event); return (result); } void isc_task_shutdown(isc_task_t *task) { isc_boolean_t was_idle; /* * Shutdown 'task'. */ REQUIRE(VALID_TASK(task)); LOCK(&task->lock); was_idle = task_shutdown(task); UNLOCK(&task->lock); if (was_idle) task_ready(task); } void isc_task_destroy(isc_task_t **taskp) { /* * Destroy '*taskp'. */ REQUIRE(taskp != NULL); isc_task_shutdown(*taskp); isc_task_detach(taskp); } void isc_task_setname(isc_task_t *task, const char *name, void *tag) { /* * Name 'task'. */ REQUIRE(VALID_TASK(task)); #ifdef ISC_TASK_NAMES LOCK(&task->lock); memset(task->name, 0, sizeof(task->name)); strncpy(task->name, name, sizeof(task->name) - 1); task->tag = tag; UNLOCK(&task->lock); #else UNUSED(name); UNUSED(tag); #endif } const char * isc_task_getname(isc_task_t *task) { return (task->name); } void * isc_task_gettag(isc_task_t *task) { return (task->tag); } /*** *** Task Manager. ***/ static void dispatch(isc_taskmgr_t *manager) { isc_task_t *task; #ifndef ISC_PLATFORM_USETHREADS unsigned int total_dispatch_count = 0; isc_tasklist_t ready_tasks; #endif /* ISC_PLATFORM_USETHREADS */ REQUIRE(VALID_MANAGER(manager)); /* * Again we're trying to hold the lock for as short a time as possible * and to do as little locking and unlocking as possible. * * In both while loops, the appropriate lock must be held before the * while body starts. Code which acquired the lock at the top of * the loop would be more readable, but would result in a lot of * extra locking. Compare: * * Straightforward: * * LOCK(); * ... * UNLOCK(); * while (expression) { * LOCK(); * ... * UNLOCK(); * * Unlocked part here... * * LOCK(); * ... * UNLOCK(); * } * * Note how if the loop continues we unlock and then immediately lock. * For N iterations of the loop, this code does 2N+1 locks and 2N+1 * unlocks. Also note that the lock is not held when the while * condition is tested, which may or may not be important, depending * on the expression. * * As written: * * LOCK(); * while (expression) { * ... * UNLOCK(); * * Unlocked part here... * * LOCK(); * ... * } * UNLOCK(); * * For N iterations of the loop, this code does N+1 locks and N+1 * unlocks. The while expression is always protected by the lock. */ #ifndef ISC_PLATFORM_USETHREADS ISC_LIST_INIT(ready_tasks); #endif LOCK(&manager->lock); while (!FINISHED(manager)) { #ifdef ISC_PLATFORM_USETHREADS /* * For reasons similar to those given in the comment in * isc_task_send() above, it is safe for us to dequeue * the task while only holding the manager lock, and then * change the task to running state while only holding the * task lock. */ while ((EMPTY(manager->ready_tasks) || manager->exclusive_requested) && !FINISHED(manager)) { XTHREADTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_WAIT, "wait")); WAIT(&manager->work_available, &manager->lock); XTHREADTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TASK, ISC_MSG_AWAKE, "awake")); } #else /* ISC_PLATFORM_USETHREADS */ if (total_dispatch_count >= DEFAULT_TASKMGR_QUANTUM || EMPTY(manager->ready_tasks)) break; #endif /* ISC_PLATFORM_USETHREADS */ XTHREADTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TASK, ISC_MSG_WORKING, "working")); task = HEAD(manager->ready_tasks); if (task != NULL) { unsigned int dispatch_count = 0; isc_boolean_t done = ISC_FALSE; isc_boolean_t requeue = ISC_FALSE; isc_boolean_t finished = ISC_FALSE; isc_event_t *event; INSIST(VALID_TASK(task)); /* * Note we only unlock the manager lock if we actually * have a task to do. We must reacquire the manager * lock before exiting the 'if (task != NULL)' block. */ DEQUEUE(manager->ready_tasks, task, ready_link); manager->tasks_running++; UNLOCK(&manager->lock); LOCK(&task->lock); INSIST(task->state == task_state_ready); task->state = task_state_running; XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_RUNNING, "running")); do { if (!EMPTY(task->events)) { event = HEAD(task->events); DEQUEUE(task->events, event, ev_link); /* * Execute the event action. */ XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TASK, ISC_MSG_EXECUTE, "execute action")); if (event->ev_action != NULL) { UNLOCK(&task->lock); (event->ev_action)(task,event); LOCK(&task->lock); } dispatch_count++; #ifndef ISC_PLATFORM_USETHREADS total_dispatch_count++; #endif /* ISC_PLATFORM_USETHREADS */ } if (task->references == 0 && EMPTY(task->events) && !TASK_SHUTTINGDOWN(task)) { isc_boolean_t was_idle; /* * There are no references and no * pending events for this task, * which means it will not become * runnable again via an external * action (such as sending an event * or detaching). * * We initiate shutdown to prevent * it from becoming a zombie. * * We do this here instead of in * the "if EMPTY(task->events)" block * below because: * * If we post no shutdown events, * we want the task to finish. * * If we did post shutdown events, * will still want the task's * quantum to be applied. */ was_idle = task_shutdown(task); INSIST(!was_idle); } if (EMPTY(task->events)) { /* * Nothing else to do for this task * right now. */ XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TASK, ISC_MSG_EMPTY, "empty")); if (task->references == 0 && TASK_SHUTTINGDOWN(task)) { /* * The task is done. */ XTRACE(isc_msgcat_get( isc_msgcat, ISC_MSGSET_TASK, ISC_MSG_DONE, "done")); finished = ISC_TRUE; task->state = task_state_done; } else task->state = task_state_idle; done = ISC_TRUE; } else if (dispatch_count >= task->quantum) { /* * Our quantum has expired, but * there is more work to be done. * We'll requeue it to the ready * queue later. * * We don't check quantum until * dispatching at least one event, * so the minimum quantum is one. */ XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TASK, ISC_MSG_QUANTUM, "quantum")); task->state = task_state_ready; requeue = ISC_TRUE; done = ISC_TRUE; } } while (!done); UNLOCK(&task->lock); if (finished) task_finished(task); LOCK(&manager->lock); manager->tasks_running--; #ifdef ISC_PLATFORM_USETHREADS if (manager->exclusive_requested && manager->tasks_running == 1) { SIGNAL(&manager->exclusive_granted); } #endif /* ISC_PLATFORM_USETHREADS */ if (requeue) { /* * We know we're awake, so we don't have * to wakeup any sleeping threads if the * ready queue is empty before we requeue. * * A possible optimization if the queue is * empty is to 'goto' the 'if (task != NULL)' * block, avoiding the ENQUEUE of the task * and the subsequent immediate DEQUEUE * (since it is the only executable task). * We don't do this because then we'd be * skipping the exit_requested check. The * cost of ENQUEUE is low anyway, especially * when you consider that we'd have to do * an extra EMPTY check to see if we could * do the optimization. If the ready queue * were usually nonempty, the 'optimization' * might even hurt rather than help. */ #ifdef ISC_PLATFORM_USETHREADS ENQUEUE(manager->ready_tasks, task, ready_link); #else ENQUEUE(ready_tasks, task, ready_link); #endif } } } #ifndef ISC_PLATFORM_USETHREADS ISC_LIST_APPENDLIST(manager->ready_tasks, ready_tasks, ready_link); #endif UNLOCK(&manager->lock); } #ifdef ISC_PLATFORM_USETHREADS static isc_threadresult_t #ifdef _WIN32 WINAPI #endif run(void *uap) { isc_taskmgr_t *manager = uap; XTHREADTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_STARTING, "starting")); dispatch(manager); XTHREADTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_EXITING, "exiting")); return ((isc_threadresult_t)0); } #endif /* ISC_PLATFORM_USETHREADS */ static void manager_free(isc_taskmgr_t *manager) { isc_mem_t *mctx; #ifdef ISC_PLATFORM_USETHREADS (void)isc_condition_destroy(&manager->exclusive_granted); (void)isc_condition_destroy(&manager->work_available); isc_mem_put(manager->mctx, manager->threads, manager->workers * sizeof (isc_thread_t)); #endif /* ISC_PLATFORM_USETHREADS */ DESTROYLOCK(&manager->lock); manager->magic = 0; mctx = manager->mctx; isc_mem_put(mctx, manager, sizeof *manager); isc_mem_detach(&mctx); } isc_result_t isc_taskmgr_create(isc_mem_t *mctx, unsigned int workers, unsigned int default_quantum, isc_taskmgr_t **managerp) { isc_result_t result; unsigned int i, started = 0; isc_taskmgr_t *manager; /* * Create a new task manager. */ REQUIRE(workers > 0); REQUIRE(managerp != NULL && *managerp == NULL); #ifndef ISC_PLATFORM_USETHREADS UNUSED(i); UNUSED(started); UNUSED(workers); if (taskmgr != NULL) { taskmgr->refs++; *managerp = taskmgr; return (ISC_R_SUCCESS); } #endif /* ISC_PLATFORM_USETHREADS */ manager = isc_mem_get(mctx, sizeof *manager); if (manager == NULL) return (ISC_R_NOMEMORY); manager->magic = TASK_MANAGER_MAGIC; manager->mctx = NULL; manager->workers = 0; if (isc_mutex_init(&manager->lock) != ISC_R_SUCCESS) { UNEXPECTED_ERROR(__FILE__, __LINE__, "isc_mutex_init() %s", isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_FAILED, "failed")); result = ISC_R_UNEXPECTED; goto cleanup_mgr; } #ifdef ISC_PLATFORM_USETHREADS manager->threads = isc_mem_get(mctx, workers * sizeof (isc_thread_t)); if (manager->threads == NULL) { result = ISC_R_NOMEMORY; goto cleanup_lock; } if (isc_condition_init(&manager->work_available) != ISC_R_SUCCESS) { UNEXPECTED_ERROR(__FILE__, __LINE__, "isc_condition_init() %s", isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_FAILED, "failed")); result = ISC_R_UNEXPECTED; goto cleanup_threads; } if (isc_condition_init(&manager->exclusive_granted) != ISC_R_SUCCESS) { UNEXPECTED_ERROR(__FILE__, __LINE__, "isc_condition_init() %s", isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL, ISC_MSG_FAILED, "failed")); result = ISC_R_UNEXPECTED; goto cleanup_workavailable; } #endif /* ISC_PLATFORM_USETHREADS */ if (default_quantum == 0) default_quantum = DEFAULT_DEFAULT_QUANTUM; manager->default_quantum = default_quantum; INIT_LIST(manager->tasks); INIT_LIST(manager->ready_tasks); manager->tasks_running = 0; manager->exclusive_requested = ISC_FALSE; manager->exiting = ISC_FALSE; manager->workers = 0; isc_mem_attach(mctx, &manager->mctx); #ifdef ISC_PLATFORM_USETHREADS LOCK(&manager->lock); /* * Start workers. */ for (i = 0; i < workers; i++) { if (isc_thread_create(run, manager, &manager->threads[manager->workers]) == ISC_R_SUCCESS) { manager->workers++; started++; } } UNLOCK(&manager->lock); if (started == 0) { manager_free(manager); return (ISC_R_NOTHREADS); } isc_thread_setconcurrency(workers); #else /* ISC_PLATFORM_USETHREADS */ manager->refs = 1; taskmgr = manager; #endif /* ISC_PLATFORM_USETHREADS */ *managerp = manager; return (ISC_R_SUCCESS); #ifdef ISC_PLATFORM_USETHREADS cleanup_workavailable: (void)isc_condition_destroy(&manager->work_available); cleanup_threads: isc_mem_put(mctx, manager->threads, workers * sizeof (isc_thread_t)); cleanup_lock: DESTROYLOCK(&manager->lock); #endif cleanup_mgr: isc_mem_put(mctx, manager, sizeof *manager); return (result); } void isc_taskmgr_destroy(isc_taskmgr_t **managerp) { isc_taskmgr_t *manager; isc_task_t *task; unsigned int i; /* * Destroy '*managerp'. */ REQUIRE(managerp != NULL); manager = *managerp; REQUIRE(VALID_MANAGER(manager)); #ifndef ISC_PLATFORM_USETHREADS UNUSED(i); if (manager->refs > 1) { manager->refs--; *managerp = NULL; return; } #endif /* ISC_PLATFORM_USETHREADS */ XTHREADTRACE("isc_taskmgr_destroy"); /* * Only one non-worker thread may ever call this routine. * If a worker thread wants to initiate shutdown of the * task manager, it should ask some non-worker thread to call * isc_taskmgr_destroy(), e.g. by signalling a condition variable * that the startup thread is sleeping on. */ /* * Unlike elsewhere, we're going to hold this lock a long time. * We need to do so, because otherwise the list of tasks could * change while we were traversing it. * * This is also the only function where we will hold both the * task manager lock and a task lock at the same time. */ LOCK(&manager->lock); /* * Make sure we only get called once. */ INSIST(!manager->exiting); manager->exiting = ISC_TRUE; /* * Post shutdown event(s) to every task (if they haven't already been * posted). */ for (task = HEAD(manager->tasks); task != NULL; task = NEXT(task, link)) { LOCK(&task->lock); if (task_shutdown(task)) ENQUEUE(manager->ready_tasks, task, ready_link); UNLOCK(&task->lock); } #ifdef ISC_PLATFORM_USETHREADS /* * Wake up any sleeping workers. This ensures we get work done if * there's work left to do, and if there are already no tasks left * it will cause the workers to see manager->exiting. */ BROADCAST(&manager->work_available); UNLOCK(&manager->lock); /* * Wait for all the worker threads to exit. */ for (i = 0; i < manager->workers; i++) (void)isc_thread_join(manager->threads[i], NULL); #else /* ISC_PLATFORM_USETHREADS */ /* * Dispatch the shutdown events. */ UNLOCK(&manager->lock); while (isc__taskmgr_ready()) (void)isc__taskmgr_dispatch(); INSIST(ISC_LIST_EMPTY(manager->tasks)); #endif /* ISC_PLATFORM_USETHREADS */ manager_free(manager); *managerp = NULL; } #ifndef ISC_PLATFORM_USETHREADS isc_boolean_t isc__taskmgr_ready(void) { if (taskmgr == NULL) return (ISC_FALSE); return (ISC_TF(!ISC_LIST_EMPTY(taskmgr->ready_tasks))); } isc_result_t isc__taskmgr_dispatch(void) { isc_taskmgr_t *manager = taskmgr; if (taskmgr == NULL) return (ISC_R_NOTFOUND); dispatch(manager); return (ISC_R_SUCCESS); } #endif /* ISC_PLATFORM_USETHREADS */ isc_result_t isc_task_beginexclusive(isc_task_t *task) { #ifdef ISC_PLATFORM_USETHREADS isc_taskmgr_t *manager = task->manager; REQUIRE(task->state == task_state_running); LOCK(&manager->lock); if (manager->exclusive_requested) { UNLOCK(&manager->lock); return (ISC_R_LOCKBUSY); } manager->exclusive_requested = ISC_TRUE; while (manager->tasks_running > 1) { WAIT(&manager->exclusive_granted, &manager->lock); } UNLOCK(&manager->lock); #else UNUSED(task); #endif return (ISC_R_SUCCESS); } void isc_task_endexclusive(isc_task_t *task) { #ifdef ISC_PLATFORM_USETHREADS isc_taskmgr_t *manager = task->manager; REQUIRE(task->state == task_state_running); LOCK(&manager->lock); REQUIRE(manager->exclusive_requested); manager->exclusive_requested = ISC_FALSE; BROADCAST(&manager->work_available); UNLOCK(&manager->lock); #else UNUSED(task); #endif }