diff options
Diffstat (limited to 'nsprpub/pr/src/misc/pralarm.c')
| -rw-r--r-- | nsprpub/pr/src/misc/pralarm.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/nsprpub/pr/src/misc/pralarm.c b/nsprpub/pr/src/misc/pralarm.c new file mode 100644 index 000000000..8f642bb16 --- /dev/null +++ b/nsprpub/pr/src/misc/pralarm.c @@ -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 */ + + + |