michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "primpl.h"
michael@0: 
michael@0: /**********************************************************************/
michael@0: /******************************* PRALARM ******************************/
michael@0: /**********************************************************************/
michael@0: 
michael@0: #include "obsolete/pralarm.h"
michael@0: 
michael@0: struct PRAlarmID {                       /* typedef'd in pralarm.h       */
michael@0:     PRCList list;                        /* circular list linkage        */
michael@0:     PRAlarm *alarm;                      /* back pointer to owning alarm */
michael@0:     PRPeriodicAlarmFn function;          /* function to call for notify  */
michael@0:     void *clientData;                    /* opaque client context        */
michael@0:     PRIntervalTime period;               /* the client defined period    */
michael@0:     PRUint32 rate;                       /* rate of notification         */
michael@0: 
michael@0:     PRUint32 accumulator;                /* keeps track of # notifies    */
michael@0:     PRIntervalTime epoch;                /* when timer was started       */
michael@0:     PRIntervalTime nextNotify;           /* when we'll next do our thing */
michael@0:     PRIntervalTime lastNotify;           /* when we last did our thing   */
michael@0: };
michael@0: 
michael@0: typedef enum {alarm_active, alarm_inactive} _AlarmState;
michael@0: 
michael@0: struct PRAlarm {                         /* typedef'd in pralarm.h       */
michael@0:     PRCList timers;                      /* base of alarm ids list       */
michael@0:     PRLock *lock;                        /* lock used to protect data    */
michael@0:     PRCondVar *cond;                     /* condition that used to wait  */
michael@0:     PRThread *notifier;                  /* thread to deliver notifies   */
michael@0:     PRAlarmID *current;                  /* current alarm being served   */
michael@0:     _AlarmState state;                   /* used to delete the alarm     */
michael@0: };
michael@0: 
michael@0: static PRAlarmID *pr_getNextAlarm(PRAlarm *alarm, PRAlarmID *id)
michael@0: {
michael@0: /*
michael@0:  * Puts 'id' back into the sorted list iff it's not NULL.
michael@0:  * Removes the first element from the list and returns it (or NULL).
michael@0:  * List is "assumed" to be short.
michael@0:  *
michael@0:  * NB: Caller is providing locking
michael@0:  */
michael@0:     PRCList *timer;
michael@0:     PRAlarmID *result = id;
michael@0:     PRIntervalTime now = PR_IntervalNow();
michael@0: 
michael@0:     if (!PR_CLIST_IS_EMPTY(&alarm->timers))
michael@0:     {    
michael@0:         if (id != NULL)  /* have to put this id back in */
michael@0:         {        
michael@0:             PRIntervalTime idDelta = now - id->nextNotify;
michael@0:             timer = alarm->timers.next;
michael@0:             do
michael@0:             {
michael@0:                 result = (PRAlarmID*)timer;
michael@0:                 if ((PRIntervalTime)(now - result->nextNotify) > idDelta)
michael@0:                 {
michael@0:                     PR_INSERT_BEFORE(&id->list, &alarm->timers);
michael@0:                     break;
michael@0:                 }
michael@0:                 timer = timer->next;
michael@0:             } while (timer != &alarm->timers);
michael@0:         }
michael@0:         result = (PRAlarmID*)(timer = PR_LIST_HEAD(&alarm->timers));
michael@0:         PR_REMOVE_LINK(timer);  /* remove it from the list */
michael@0:     }
michael@0: 
michael@0:     return result;
michael@0: }  /* pr_getNextAlarm */
michael@0: 
michael@0: static PRIntervalTime pr_PredictNextNotifyTime(PRAlarmID *id)
michael@0: {
michael@0:     PRIntervalTime delta;
michael@0:     PRFloat64 baseRate = (PRFloat64)id->period / (PRFloat64)id->rate;
michael@0:     PRFloat64 offsetFromEpoch = (PRFloat64)id->accumulator * baseRate;
michael@0: 
michael@0:     id->accumulator += 1;  /* every call advances to next period */
michael@0:     id->lastNotify = id->nextNotify;  /* just keeping track of things */
michael@0:     id->nextNotify = (PRIntervalTime)(offsetFromEpoch + 0.5);
michael@0: 
michael@0:     delta = id->nextNotify - id->lastNotify;
michael@0:     return delta;
michael@0: }  /* pr_PredictNextNotifyTime */
michael@0: 
michael@0: static void PR_CALLBACK pr_alarmNotifier(void *arg)
michael@0: {
michael@0:     /*
michael@0:      * This is the root of the notifier thread. There is one such thread
michael@0:      * for each PRAlarm. It may service an arbitrary (though assumed to be
michael@0:      * small) number of alarms using the same thread and structure. It
michael@0:      * continues to run until the alarm is destroyed.
michael@0:      */
michael@0:     PRAlarmID *id = NULL;
michael@0:     PRAlarm *alarm = (PRAlarm*)arg;
michael@0:     enum {notify, abort, scan} why = scan;
michael@0: 
michael@0:     while (why != abort)
michael@0:     {
michael@0:         PRIntervalTime pause;
michael@0: 
michael@0:         PR_Lock(alarm->lock);
michael@0:         while (why == scan)
michael@0:         {
michael@0:             alarm->current = NULL;  /* reset current id */
michael@0:             if (alarm->state == alarm_inactive) why = abort;  /* we're toast */
michael@0:             else if (why == scan)  /* the dominant case */
michael@0:             {
michael@0:                 id = pr_getNextAlarm(alarm, id);  /* even if it's the same */
michael@0:                 if (id == NULL)  /* there are no alarms set */
michael@0:                     (void)PR_WaitCondVar(alarm->cond, PR_INTERVAL_NO_TIMEOUT);
michael@0:                 else
michael@0:                 {
michael@0:                     pause = id->nextNotify - (PR_IntervalNow() - id->epoch);
michael@0:                     if ((PRInt32)pause <= 0)  /* is this one's time up? */
michael@0:                     {
michael@0:                         why = notify;  /* set up to do our thing */
michael@0:                         alarm->current = id;  /* id we're about to schedule */
michael@0:                     }
michael@0:                     else
michael@0:                         (void)PR_WaitCondVar(alarm->cond, pause);  /* dally */
michael@0:                 }
michael@0:             }
michael@0:         }
michael@0:         PR_Unlock(alarm->lock);
michael@0: 
michael@0:         if (why == notify)
michael@0:         {
michael@0:             (void)pr_PredictNextNotifyTime(id);
michael@0:             if (!id->function(id, id->clientData, ~pause))
michael@0:             {
michael@0:                 /*
michael@0:                  * Notified function decided not to continue. Free
michael@0:                  * the alarm id to make sure it doesn't get back on
michael@0:                  * the list.
michael@0:                  */
michael@0:                 PR_DELETE(id);  /* free notifier object */
michael@0:                 id = NULL;  /* so it doesn't get back into the list */
michael@0:             }
michael@0:             why = scan;  /* so we can cycle through the loop again */
michael@0:         }
michael@0:     }
michael@0: 
michael@0: }  /* pr_alarm_notifier */
michael@0: 
michael@0: PR_IMPLEMENT(PRAlarm*) PR_CreateAlarm(void)
michael@0: {
michael@0:     PRAlarm *alarm = PR_NEWZAP(PRAlarm);
michael@0:     if (alarm != NULL)
michael@0:     {
michael@0:         if ((alarm->lock = PR_NewLock()) == NULL) goto done;
michael@0:         if ((alarm->cond = PR_NewCondVar(alarm->lock)) == NULL) goto done;
michael@0:         alarm->state = alarm_active;
michael@0:         PR_INIT_CLIST(&alarm->timers);
michael@0:         alarm->notifier = PR_CreateThread(
michael@0:             PR_USER_THREAD, pr_alarmNotifier, alarm,
michael@0:             PR_GetThreadPriority(PR_GetCurrentThread()),
michael@0:             PR_LOCAL_THREAD, PR_JOINABLE_THREAD, 0);
michael@0:         if (alarm->notifier == NULL) goto done;
michael@0:     }
michael@0:     return alarm;
michael@0: 
michael@0: done:
michael@0:     if (alarm->cond != NULL) PR_DestroyCondVar(alarm->cond);
michael@0:     if (alarm->lock != NULL) PR_DestroyLock(alarm->lock);
michael@0:     PR_DELETE(alarm);
michael@0:     return NULL;
michael@0: }  /* CreateAlarm */
michael@0: 
michael@0: PR_IMPLEMENT(PRStatus) PR_DestroyAlarm(PRAlarm *alarm)
michael@0: {
michael@0:     PRStatus rv;
michael@0: 
michael@0:     PR_Lock(alarm->lock);
michael@0:     alarm->state = alarm_inactive;
michael@0:     rv = PR_NotifyCondVar(alarm->cond);
michael@0:     PR_Unlock(alarm->lock);
michael@0: 
michael@0:     if (rv == PR_SUCCESS)
michael@0:         rv = PR_JoinThread(alarm->notifier);
michael@0:     if (rv == PR_SUCCESS)
michael@0:     {
michael@0:         PR_DestroyCondVar(alarm->cond);
michael@0:         PR_DestroyLock(alarm->lock);
michael@0:         PR_DELETE(alarm);
michael@0:     }
michael@0:     return rv;
michael@0: }  /* PR_DestroyAlarm */
michael@0: 
michael@0: PR_IMPLEMENT(PRAlarmID*) PR_SetAlarm(
michael@0:     PRAlarm *alarm, PRIntervalTime period, PRUint32 rate,
michael@0:     PRPeriodicAlarmFn function, void *clientData)
michael@0: {
michael@0:     /*
michael@0:      * Create a new periodic alarm an existing current structure.
michael@0:      * Set up the context and compute the first notify time (immediate).
michael@0:      * Link the new ID into the head of the list (since it's notifying
michael@0:      * immediately).
michael@0:      */
michael@0: 
michael@0:     PRAlarmID *id = PR_NEWZAP(PRAlarmID);
michael@0: 
michael@0:     if (!id)
michael@0:         return NULL;
michael@0: 
michael@0:     id->alarm = alarm;
michael@0:     PR_INIT_CLIST(&id->list);
michael@0:     id->function = function;
michael@0:     id->clientData = clientData;
michael@0:     id->period = period;
michael@0:     id->rate = rate;
michael@0:     id->epoch = id->nextNotify = PR_IntervalNow();
michael@0:     (void)pr_PredictNextNotifyTime(id);
michael@0: 
michael@0:     PR_Lock(alarm->lock);
michael@0:     PR_INSERT_BEFORE(&id->list, &alarm->timers);
michael@0:     PR_NotifyCondVar(alarm->cond);
michael@0:     PR_Unlock(alarm->lock);
michael@0: 
michael@0:     return id;
michael@0: }  /* PR_SetAlarm */
michael@0: 
michael@0: PR_IMPLEMENT(PRStatus) PR_ResetAlarm(
michael@0:     PRAlarmID *id, PRIntervalTime period, PRUint32 rate)
michael@0: {
michael@0:     /*
michael@0:      * Can only be called from within the notify routine. Doesn't
michael@0:      * need locking because it can only be called from within the
michael@0:      * notify routine.
michael@0:      */
michael@0:     if (id != id->alarm->current)
michael@0:         return PR_FAILURE;
michael@0:     id->period = period;
michael@0:     id->rate = rate;
michael@0:     id->accumulator = 1;
michael@0:     id->epoch = PR_IntervalNow();
michael@0:     (void)pr_PredictNextNotifyTime(id);
michael@0:     return PR_SUCCESS;
michael@0: }  /* PR_ResetAlarm */
michael@0: 
michael@0: 
michael@0: