summaryrefslogtreecommitdiffstats
path: root/nsprpub/pr/src/misc/pralarm.c
diff options
context:
space:
mode:
Diffstat (limited to 'nsprpub/pr/src/misc/pralarm.c')
-rw-r--r--nsprpub/pr/src/misc/pralarm.c263
1 files changed, 263 insertions, 0 deletions
diff --git a/nsprpub/pr/src/misc/pralarm.c b/nsprpub/pr/src/misc/pralarm.c
new file mode 100644
index 0000000000..8130215c24
--- /dev/null
+++ b/nsprpub/pr/src/misc/pralarm.c
@@ -0,0 +1,263 @@
+/* -*- 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 */
+
+
+