timer.c

bind-3.2.

/*
 * Copyright (C) 1998-2001  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 INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM 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: timer.c,v 1.64 2001/06/04 19:33:29 tale Exp $ */

#include <config.h>

#include <isc/condition.h>
#include <isc/heap.h>
#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/msgs.h>
#include <isc/platform.h>
#include <isc/task.h>
#include <isc/thread.h>
#include <isc/time.h>
#include <isc/timer.h>
#include <isc/util.h>

#ifndef ISC_PLATFORM_USETHREADS
#include "timer_p.h"
#endif /* ISC_PLATFORM_USETHREADS */

#ifdef ISC_TIMER_TRACE
#define XTRACE(s)			printf("%s\n", (s))
#define XTRACEID(s, t)			printf("%s %p\n", (s), (t))
#define XTRACETIME(s, d)		printf("%s %u.%09u\n", (s), \
					       (d).seconds, (d).nanoseconds)
#define XTRACETIMER(s, t, d)		printf("%s %p %u.%09u\n", (s), (t), \
					       (d).seconds, (d).nanoseconds)
#else
#define XTRACE(s)
#define XTRACEID(s, t)
#define XTRACETIME(s, d)
#define XTRACETIMER(s, t, d)
#endif /* ISC_TIMER_TRACE */

#define TIMER_MAGIC			ISC_MAGIC('T', 'I', 'M', 'R')
#define VALID_TIMER(t)			ISC_MAGIC_VALID(t, TIMER_MAGIC)

struct isc_timer {
	/* Not locked. */
	unsigned int			magic;
	isc_timermgr_t *		manager;
	isc_mutex_t			lock;
	/* Locked by timer lock. */
	unsigned int			references;
	isc_time_t			idle;
	/* Locked by manager lock. */
	isc_timertype_t			type;
	isc_time_t			expires;
	isc_interval_t			interval;
	isc_task_t *			task;
	isc_taskaction_t		action;
	void *				arg;
	unsigned int			index;
	isc_time_t			due;
	LINK(isc_timer_t)		link;
};

#define TIMER_MANAGER_MAGIC		ISC_MAGIC('T', 'I', 'M', 'M')
#define VALID_MANAGER(m)		ISC_MAGIC_VALID(m, TIMER_MANAGER_MAGIC)

struct isc_timermgr {
	/* Not locked. */
	unsigned int			magic;
	isc_mem_t *			mctx;
	isc_mutex_t			lock;
	/* Locked by manager lock. */
	isc_boolean_t			done;
	LIST(isc_timer_t)		timers;
	unsigned int			nscheduled;
	isc_time_t			due;
#ifdef ISC_PLATFORM_USETHREADS
	isc_condition_t			wakeup;
	isc_thread_t			thread;
#else /* ISC_PLATFORM_USETHREADS */
	unsigned int			refs;
#endif /* ISC_PLATFORM_USETHREADS */
	isc_heap_t *			heap;
};

#ifndef ISC_PLATFORM_USETHREADS
/*
 * If threads are not in use, there can be only one.
 */
static isc_timermgr_t *timermgr = NULL;
#endif /* ISC_PLATFORM_USETHREADS */

static inline isc_result_t
schedule(isc_timer_t *timer, isc_time_t *now, isc_boolean_t signal_ok) {
	isc_result_t result;
	isc_timermgr_t *manager;
	isc_time_t due;
	int cmp;

	/*
	 * Note: the caller must ensure locking.
	 */

	REQUIRE(timer->type != isc_timertype_inactive);

#ifndef ISC_PLATFORM_USETHREADS
	UNUSED(signal_ok);
#endif /* ISC_PLATFORM_USETHREADS */

	/*
	 * Compute the new due time.
	 */
	if (timer->type == isc_timertype_ticker) {
		result = isc_time_add(now, &timer->interval, &due);
		if (result != ISC_R_SUCCESS)
			return (result);
	} else {
		if (isc_time_isepoch(&timer->idle))
			due = timer->expires;
		else if (isc_time_isepoch(&timer->expires))
			due = timer->idle;
		else if (isc_time_compare(&timer->idle, &timer->expires) < 0)
			due = timer->idle;
		else
			due = timer->expires;
	}

	/*
	 * Schedule the timer.
	 */
	manager = timer->manager;
	if (timer->index > 0) {
		/*
		 * Already scheduled.
		 */
		cmp = isc_time_compare(&due, &timer->due);
		timer->due = due;
		switch (cmp) {
		case -1:
			isc_heap_increased(manager->heap, timer->index);
			break;
		case 1:
			isc_heap_decreased(manager->heap, timer->index);
			break;
		case 0:
			/* Nothing to do. */
			break;
		}
	} else {
		timer->due = due;
		result = isc_heap_insert(manager->heap, timer);
		if (result != ISC_R_SUCCESS) {
			INSIST(result == ISC_R_NOMEMORY);
			return (ISC_R_NOMEMORY);
		}
		manager->nscheduled++;
	}

	XTRACETIMER(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TIMER,
				   ISC_MSG_SCHEDULE, "schedule"), timer, due);

	/*
	 * If this timer is at the head of the queue, we need to ensure
	 * that we won't miss it if it has a more recent due time than
	 * the current "next" timer.  We do this either by waking up the
	 * run thread, or explicitly setting the value in the manager.
	 */
#ifdef ISC_PLATFORM_USETHREADS
	if (timer->index == 1 && signal_ok) {
		XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TIMER,
				      ISC_MSG_SIGNALSCHED,
				      "signal (schedule)"));
		SIGNAL(&manager->wakeup);
	}
#else /* ISC_PLATFORM_USETHREADS */
	if (timer->index == 1 &&
	    isc_time_compare(&timer->due, &manager->due) < 0)
		manager->due = timer->due;
#endif /* ISC_PLATFORM_USETHREADS */

	return (ISC_R_SUCCESS);
}

static inline void
deschedule(isc_timer_t *timer) {
	isc_boolean_t need_wakeup = ISC_FALSE;
	isc_timermgr_t *manager;

	/*
	 * The caller must ensure locking.
	 */

	manager = timer->manager;
	if (timer->index > 0) {
		if (timer->index == 1)
			need_wakeup = ISC_TRUE;
		isc_heap_delete(manager->heap, timer->index);
		timer->index = 0;
		INSIST(manager->nscheduled > 0);
		manager->nscheduled--;
#ifdef ISC_PLATFORM_USETHREADS
		if (need_wakeup) {
			XTRACE(isc_msgcat_get(isc_msgcat, ISC_MSGSET_TIMER,
					      ISC_MSG_SIGNALDESCHED,
					      "signal (deschedule)"));
			SIGNAL(&manager->wakeup);
		}
#endif /* ISC_PLATFORM_USETHREADS */
	}
}

static void
destroy(isc_timer_t *timer) {
	isc_timermgr_t *manager = timer->manager;

	/*
	 * The caller must ensure it is safe to destroy the timer.
	 */

	LOCK(&manager->lock);

	isc_task_purgerange(timer->task,
			    timer,
			    ISC_TIMEREVENT_FIRSTEVENT,
			    ISC_TIMEREVENT_LASTEVENT,
			    NULL);
	deschedule(timer);
	UNLINK(manager->timers, timer, link);

	UNLOCK(&manager->lock);

	isc_task_detach(&timer->task);
	DESTROYLOCK(&timer->lock);
	timer->magic = 0;
	isc_mem_put(manager->mctx, timer, sizeof *timer);
}

isc_result_t
isc_timer_create(isc_timermgr_t *manager, isc_timertype_t type,
		 isc_time_t *expires, isc_interval_t *interval,
		 isc_task_t *task, isc_taskaction_t action, const void *arg,
		 isc_timer_t **timerp)
{
	isc_timer_t *timer;
	isc_result_t result;
	isc_time_t now;

	/*
	 * Create a new 'type' timer managed by 'manager'.  The timers
	 * parameters are specified by 'expires' and 'interval'.  Events
	 * will be posted to 'task' and when dispatched 'action' will be
	 * called with 'arg' as the arg value.  The new timer is returned
	 * in 'timerp'.
	 */

	REQUIRE(VALID_MANAGER(manager));
	REQUIRE(task != NULL);
	REQUIRE(action != NULL);
	if (expires == NULL)
		expires = isc_time_epoch;
	if (interval == NULL)
		interval = isc_interval_zero;
	REQUIRE(type == isc_timertype_inactive ||
		!(isc_time_isepoch(expires) && isc_interval_iszero(interval)));
	REQUIRE(timerp != NULL && *timerp == NULL);

	/*
	 * Get current time.
	 */
	if (type != isc_timertype_inactive) {
		result = isc_time_now(&now);
		if (result != ISC_R_SUCCESS) {
			UNEXPECTED_ERROR(__FILE__, __LINE__,
					 "isc_time_now() %s: %s",
					 isc_msgcat_get(isc_msgcat,
							ISC_MSGSET_GENERAL,
							ISC_MSG_FAILED,
							"failed"),
					 isc_result_totext(result));
			return (ISC_R_UNEXPECTED);
		}
	} else {
		/*
		 * We don't have to do this, but it keeps the compiler from
		 * complaining about "now" possibly being used without being
		 * set, even though it will never actually happen.
		 */
		isc_time_settoepoch(&now);
	}


	timer = isc_mem_get(manager->mctx, sizeof *timer);
	if (timer == NULL)
		return (ISC_R_NOMEMORY);

	timer->manager = manager;
	timer->references = 1;

	if (type == isc_timertype_once && !isc_interval_iszero(interval)) {
		result = isc_time_add(&now, interval, &timer->idle);
		if (result != ISC_R_SUCCESS)
			return (result);
	} else
		isc_time_settoepoch(&timer->idle);

	timer->type = type;
	timer->expires = *expires;
	timer->interval = *interval;
	timer->task = NULL;
	isc_task_attach(task, &timer->task);
	timer->action = action;
	/*
	 * Removing the const attribute from "arg" is the best of two
	 * evils here.  If the timer->arg member is made const, then
	 * it affects a great many recipients of the timer event
	 * which did not pass in an "arg" that was truly const.
	 * Changing isc_timer_create() to not have "arg" prototyped as const,
	 * though, can cause compilers warnings for calls that *do*
	 * have a truly const arg.  The caller will have to carefully
	 * keep track of whether arg started as a true const.
	 */
	DE_CONST(arg, timer->arg);
	timer->index = 0;
	if (isc_mutex_init(&timer->lock) != ISC_R_SUCCESS) {
		isc_task_detach(&timer->task);
		isc_mem_put(manager->mctx, timer, sizeof *timer);
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "isc_mutex_init() %s",
				 isc_msgcat_get(isc_msgcat, ISC_MSGSET_GENERAL,
						ISC_MSG_FAILED, "failed"));
		return (ISC_R_UNEXPECTED);
	}
	ISC_LINK_INIT(timer, link);
	timer->magic = TIMER_MAGIC;

	LOCK(&manager->lock);

	/*
	 * Note we don't have to lock the timer like we normally would because
	 * there are no external references to it yet.
	 */

	if (type != isc_timertype_inactive)
		result = schedule(timer, &now, ISC_TRUE);
	else
		result = ISC_R_SUCCESS;
	if (result == ISC_R_SUCCESS)
		APPEND(manager->timers, timer, link);

	UNLOCK(&manager->lock);

	if (result != ISC_R_SUCCESS) {
		timer->magic = 0;
		DESTROYLOCK(&timer->lock);
		isc_task_detach(&timer->task);
		isc_mem_put(manager->mctx, timer, sizeof *timer);
		return (result);
	}

	*timerp = timer;

	return (ISC_R_SUCCESS);
}

isc_result_t
isc_timer_reset(isc_timer_t *timer, isc_timertype_t type,
		isc_time_t *expires, isc_interval_t *interval,
		isc_boolean_t purge)
{
	isc_time_t now;
	isc_timermgr_t *manager;
	isc_result_t result;

	/*
	 * Change the timer's type, expires, and interval values to the given
	 * values.  If 'purge' is ISC_TRUE, any pending events from this timer
	 * are purged from its task's event queue.
	 */

	REQUIRE(VALID_TIMER(timer));
	manager = timer->manager;
	REQUIRE(VALID_MANAGER(manager));
	if (expires == NULL)
		expires = isc_time_epoch;
	if (interval == NULL)
		interval = isc_interval_zero;
	REQUIRE(type == isc_timertype_inactive ||
		!(isc_time_isepoch(expires) && isc_interval_iszero(interval)));

	/*
	 * Get current time.
	 */
	if (type != isc_timertype_inactive) {
		result = isc_time_now(&now);
		if (result != ISC_R_SUCCESS) {
			UNEXPECTED_ERROR(__FILE__, __LINE__,
					 "isc_time_now() %s: %s",
					 isc_msgcat_get(isc_msgcat,
							ISC_MSGSET_GENERAL,
							ISC_MSG_FAILED,
							"failed"),
					 isc_result_totext(result));
			return (ISC_R_UNEXPECTED);
		}
	} else {
		/*
		 * We don't have to do this, but it keeps the compiler from
		 * complaining about "now" possibly being used without being
		 * set, even though it will never actually happen.
		 */
		isc_time_settoepoch(&now);
	}

	manager = timer->manager;

	LOCK(&manager->lock);
	LOCK(&timer->lock);

	if (purge)
		isc_task_purgerange(timer->task,
				    timer,
				    ISC_TIMEREVENT_FIRSTEVENT,