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