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/* -*- 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 */
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