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