/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * http://www.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is the Netscape Portable Runtime (NSPR). * * The Initial Developer of the Original Code is * Netscape Communications Corporation. * Portions created by the Initial Developer are Copyright (C) 1998-2000 * the Initial Developer. All Rights Reserved. * * Contributor(s): * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ /* ** File: pralarm.h ** Description: API to periodic alarms. ** ** ** Alarms are defined to invoke some client specified function at ** a time in the future. The notification may be a one time event ** or repeated at a fixed interval. The interval at which the next ** notification takes place may be modified by the client code only ** during the respective notification. ** ** The notification is delivered on a thread that is part of the ** alarm context (PRAlarm). The thread will inherit the priority ** of the Alarm creator. ** ** Any number of periodic alarms (PRAlarmID) may be created within ** the context of a single alarm (PRAlarm). The notifications will be ** scheduled as close to the desired time as possible. ** ** Repeating periodic notifies are expected to run at a fixed rate. ** That rate is expressed as some number of notifies per period where ** the period is much larger than a PRIntervalTime (see prinrval.h). */ #if !defined(pralarm_h) #define pralarm_h #include "prtypes.h" #include "prinrval.h" PR_BEGIN_EXTERN_C /**********************************************************************/ /************************* TYPES AND CONSTANTS ************************/ /**********************************************************************/ typedef struct PRAlarm PRAlarm; typedef struct PRAlarmID PRAlarmID; typedef PRBool (PR_CALLBACK *PRPeriodicAlarmFn)( PRAlarmID *id, void *clientData, PRUint32 late); /**********************************************************************/ /****************************** FUNCTIONS *****************************/ /**********************************************************************/ /*********************************************************************** ** FUNCTION: PR_CreateAlarm ** DESCRIPTION: ** Create an alarm context. ** INPUTS: void ** OUTPUTS: None ** RETURN: PRAlarm* ** ** SIDE EFFECTS: ** This creates an alarm context, which is an object used for subsequent ** notification creations. It also creates a thread that will be used to ** deliver the notifications that are expected to be defined. The client ** is resposible for destroying the context when appropriate. ** RESTRICTIONS: ** None. ** MEMORY: The object (PRAlarm) and a thread to support notifications. ** ALGORITHM: N/A ***********************************************************************/ NSPR_API(PRAlarm*) PR_CreateAlarm(void); /*********************************************************************** ** FUNCTION: PR_DestroyAlarm ** DESCRIPTION: ** Destroys the context created by PR_CreateAlarm(). ** INPUTS: PRAlarm* ** OUTPUTS: None ** RETURN: PRStatus ** ** SIDE EFFECTS: ** This destroys the context that was created by PR_CreateAlarm(). ** If there are any active alarms (PRAlarmID), they will be cancelled. ** Once that is done, the thread that was used to deliver the alarms ** will be joined. ** RESTRICTIONS: ** None. ** MEMORY: N/A ** ALGORITHM: N/A ***********************************************************************/ NSPR_API(PRStatus) PR_DestroyAlarm(PRAlarm *alarm); /*********************************************************************** ** FUNCTION: PR_SetAlarm ** DESCRIPTION: ** Creates a periodic notifier that is to be delivered to a specified ** function at some fixed interval. ** INPUTS: PRAlarm *alarm Parent alarm context ** PRIntervalTime period Interval over which the notifies ** are delivered. ** PRUint32 rate The rate within the interval that ** the notifies will be delivered. ** PRPeriodicAlarmFn function Entry point where the notifies ** will be delivered. ** OUTPUTS: None ** RETURN: PRAlarmID* Handle to the notifier just created ** or NULL if the request failed. ** ** SIDE EFFECTS: ** A periodic notifier is created. The notifications will be delivered ** by the alarm's internal thread at a fixed interval whose rate is the ** number of interrupts per interval specified. The first notification ** will be delivered as soon as possible, and they will continue until ** the notifier routine indicates that they should cease of the alarm ** context is destroyed (PR_DestroyAlarm). ** RESTRICTIONS: ** None. ** MEMORY: Memory for the notifier object. ** ALGORITHM: The rate at which notifications are delivered are stated ** to be "'rate' notifies per 'interval'". The exact time of ** the notification is computed based on a epoch established ** when the notifier was set. Each notification is delivered ** not ealier than the epoch plus the fixed rate times the ** notification sequence number. Such notifications have the ** potential to be late by not more than 'interval'/'rate'. ** The amount of lateness of one notification is taken into ** account on the next in an attempt to avoid long term slew. ***********************************************************************/ NSPR_API(PRAlarmID*) PR_SetAlarm( PRAlarm *alarm, PRIntervalTime period, PRUint32 rate, PRPeriodicAlarmFn function, void *clientData); /*********************************************************************** ** FUNCTION: PR_ResetAlarm ** DESCRIPTION: ** Resets an existing alarm. ** INPUTS: PRAlarmID *id Identify of the notifier. ** PRIntervalTime period Interval over which the notifies ** are delivered. ** PRUint32 rate The rate within the interval that ** the notifies will be delivered. ** OUTPUTS: None ** RETURN: PRStatus Indication of completion. ** ** SIDE EFFECTS: ** An existing alarm may have its period and rate redefined. The ** additional side effect is that the notifier's epoch is recomputed. ** The first notification delivered by the newly refreshed alarm is ** defined to be 'interval'/'rate' from the time of the reset. ** RESTRICTIONS: ** This function may only be called in the notifier for that alarm. ** MEMORY: N/A. ** ALGORITHM: See PR_SetAlarm(). ***********************************************************************/ NSPR_API(PRStatus) PR_ResetAlarm( PRAlarmID *id, PRIntervalTime period, PRUint32 rate); PR_END_EXTERN_C #endif /* !defined(pralarm_h) */ /* prinrval.h */