--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nspr/pr/src/misc/pralarm.c	Mon Jul 28 10:47:06 2014 +0200
@@ -0,0 +1,246 @@
+/* -*- 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 */
+
+
+