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Diffstat (limited to 'contrib/bind9/lib/isc/task.c')
| -rw-r--r-- | contrib/bind9/lib/isc/task.c | 1298 |
1 files changed, 0 insertions, 1298 deletions
diff --git a/contrib/bind9/lib/isc/task.c b/contrib/bind9/lib/isc/task.c deleted file mode 100644 index 5c80712..0000000 --- a/contrib/bind9/lib/isc/task.c +++ /dev/null @@ -1,1298 +0,0 @@ -/* - * Copyright (C) 2004-2006 Internet Systems Consortium, Inc. ("ISC") - * Copyright (C) 1998-2003 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 1.91.18.6 2006/01/04 23:50:23 marka Exp $ */ - -/*! \file - * \author Principal Author: Bob Halley - */ - -/* - * XXXRTH Need to document the states a task can be in, and the rules - * for changing states. - */ - -#include <config.h> - -#include <isc/condition.h> -#include <isc/event.h> -#include <isc/magic.h> -#include <isc/mem.h> -#include <isc/msgs.h> -#include <isc/platform.h> -#include <isc/string.h> -#include <isc/task.h> -#include <isc/thread.h> -#include <isc/util.h> - -#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; - isc_stdtime_t now; -#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; -#ifdef ISC_PLATFORM_USETHREADS - unsigned int workers; - 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; - isc_result_t result; - - 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; - result = isc_mutex_init(&task->lock); - if (result != ISC_R_SUCCESS) { - isc_mem_put(manager->mctx, task, sizeof(*task)); - return (result); - } - task->state = task_state_idle; - task->references = 1; - INIT_LIST(task->events); - INIT_LIST(task->on_shutdown); - task->quantum = quantum; - task->flags = 0; - task->now = 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); -} - -void -isc_task_getcurrenttime(isc_task_t *task, isc_stdtime_t *t) { - REQUIRE(VALID_TASK(task)); - REQUIRE(t != NULL); - - LOCK(&task->lock); - - *t = task->now; - - UNLOCK(&task->lock); -} - -/*** - *** 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")); - isc_stdtime_get(&task->now); - 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_free(manager->mctx, manager->threads); -#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; - result = isc_mutex_init(&manager->lock); - if (result != ISC_R_SUCCESS) - goto cleanup_mgr; - -#ifdef ISC_PLATFORM_USETHREADS - manager->workers = 0; - manager->threads = isc_mem_allocate(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; - - 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_free(mctx, manager->threads); - 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(); - if (!ISC_LIST_EMPTY(manager->tasks)) - isc_mem_printallactive(stderr); - 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 -} |
