1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ 2 /* 3 * The contents of this file are subject to the Mozilla Public 4 * License Version 1.1 (the "License"); you may not use this file 5 * except in compliance with the License. You may obtain a copy of 6 * the License at http://www.mozilla.org/MPL/ 7 * 8 * Software distributed under the License is distributed on an "AS 9 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or 10 * implied. See the License for the specific language governing 11 * rights and limitations under the License. 12 * 13 * The Original Code is the Netscape Portable Runtime (NSPR). 14 * 15 * The Initial Developer of the Original Code is Netscape 16 * Communications Corporation. Portions created by Netscape are 17 * Copyright (C) 1998-2000 Netscape Communications Corporation. All 18 * Rights Reserved. 19 * 20 * Contributor(s): 21 * 22 * Alternatively, the contents of this file may be used under the 23 * terms of the GNU General Public License Version 2 or later (the 24 * "GPL"), in which case the provisions of the GPL are applicable 25 * instead of those above. If you wish to allow use of your 26 * version of this file only under the terms of the GPL and not to 27 * allow others to use your version of this file under the MPL, 28 * indicate your decision by deleting the provisions above and 29 * replace them with the notice and other provisions required by 30 * the GPL. If you do not delete the provisions above, a recipient 31 * may use your version of this file under either the MPL or the 32 * GPL. 33 */ 34 35 /* 36 ** File: pralarm.h 37 ** Description: API to periodic alarms. 38 ** 39 ** 40 ** Alarms are defined to invoke some client specified function at 41 ** a time in the future. The notification may be a one time event 42 ** or repeated at a fixed interval. The interval at which the next 43 ** notification takes place may be modified by the client code only 44 ** during the respective notification. 45 ** 46 ** The notification is delivered on a thread that is part of the 47 ** alarm context (PRAlarm). The thread will inherit the priority 48 ** of the Alarm creator. 49 ** 50 ** Any number of periodic alarms (PRAlarmID) may be created within 51 ** the context of a single alarm (PRAlarm). The notifications will be 52 ** scheduled as close to the desired time as possible. 53 ** 54 ** Repeating periodic notifies are expected to run at a fixed rate. 55 ** That rate is expressed as some number of notifies per period where 56 ** the period is much larger than a PRIntervalTime (see prinrval.h). 57 */ 58 59 #if !defined(pralarm_h) 60 #define pralarm_h 61 62 #include "prtypes.h" 63 #include "prinrval.h" 64 65 66 PR_BEGIN_EXTERN_C 67 68 /**********************************************************************/ 69 /************************* TYPES AND CONSTANTS ************************/ 70 /**********************************************************************/ 71 72 typedef struct PRAlarm PRAlarm; 73 typedef struct PRAlarmID PRAlarmID; 74 75 typedef PRBool (PR_CALLBACK *PRPeriodicAlarmFn)( 76 PRAlarmID *id, void *clientData, PRUint32 late); 77 78 /**********************************************************************/ 79 /****************************** FUNCTIONS *****************************/ 80 /**********************************************************************/ 81 82 /*********************************************************************** 83 ** FUNCTION: PR_CreateAlarm 84 ** DESCRIPTION: 85 ** Create an alarm context. 86 ** INPUTS: void 87 ** OUTPUTS: None 88 ** RETURN: PRAlarm* 89 ** 90 ** SIDE EFFECTS: 91 ** This creates an alarm context, which is an object used for subsequent 92 ** notification creations. It also creates a thread that will be used to 93 ** deliver the notifications that are expected to be defined. The client 94 ** is resposible for destroying the context when appropriate. 95 ** RESTRICTIONS: 96 ** None. 97 ** MEMORY: The object (PRAlarm) and a thread to support notifications. 98 ** ALGORITHM: N/A 99 ***********************************************************************/ 100 NSPR_API(PRAlarm*) PR_CreateAlarm(void); 101 102 /*********************************************************************** 103 ** FUNCTION: PR_DestroyAlarm 104 ** DESCRIPTION: 105 ** Destroys the context created by PR_CreateAlarm(). 106 ** INPUTS: PRAlarm* 107 ** OUTPUTS: None 108 ** RETURN: PRStatus 109 ** 110 ** SIDE EFFECTS: 111 ** This destroys the context that was created by PR_CreateAlarm(). 112 ** If there are any active alarms (PRAlarmID), they will be cancelled. 113 ** Once that is done, the thread that was used to deliver the alarms 114 ** will be joined. 115 ** RESTRICTIONS: 116 ** None. 117 ** MEMORY: N/A 118 ** ALGORITHM: N/A 119 ***********************************************************************/ 120 NSPR_API(PRStatus) PR_DestroyAlarm(PRAlarm *alarm); 121 122 /*********************************************************************** 123 ** FUNCTION: PR_SetAlarm 124 ** DESCRIPTION: 125 ** Creates a periodic notifier that is to be delivered to a specified 126 ** function at some fixed interval. 127 ** INPUTS: PRAlarm *alarm Parent alarm context 128 ** PRIntervalTime period Interval over which the notifies 129 ** are delivered. 130 ** PRUint32 rate The rate within the interval that 131 ** the notifies will be delivered. 132 ** PRPeriodicAlarmFn function Entry point where the notifies 133 ** will be delivered. 134 ** OUTPUTS: None 135 ** RETURN: PRAlarmID* Handle to the notifier just created 136 ** or NULL if the request failed. 137 ** 138 ** SIDE EFFECTS: 139 ** A periodic notifier is created. The notifications will be delivered 140 ** by the alarm's internal thread at a fixed interval whose rate is the 141 ** number of interrupts per interval specified. The first notification 142 ** will be delivered as soon as possible, and they will continue until 143 ** the notifier routine indicates that they should cease of the alarm 144 ** context is destroyed (PR_DestroyAlarm). 145 ** RESTRICTIONS: 146 ** None. 147 ** MEMORY: Memory for the notifier object. 148 ** ALGORITHM: The rate at which notifications are delivered are stated 149 ** to be "'rate' notifies per 'interval'". The exact time of 150 ** the notification is computed based on a epoch established 151 ** when the notifier was set. Each notification is delivered 152 ** not ealier than the epoch plus the fixed rate times the 153 ** notification sequence number. Such notifications have the 154 ** potential to be late by not more than 'interval'/'rate'. 155 ** The amount of lateness of one notification is taken into 156 ** account on the next in an attempt to avoid long term slew. 157 ***********************************************************************/ 158 NSPR_API(PRAlarmID*) PR_SetAlarm( 159 PRAlarm *alarm, PRIntervalTime period, PRUint32 rate, 160 PRPeriodicAlarmFn function, void *clientData); 161 162 /*********************************************************************** 163 ** FUNCTION: PR_ResetAlarm 164 ** DESCRIPTION: 165 ** Resets an existing alarm. 166 ** INPUTS: PRAlarmID *id Identify of the notifier. 167 ** PRIntervalTime period Interval over which the notifies 168 ** are delivered. 169 ** PRUint32 rate The rate within the interval that 170 ** the notifies will be delivered. 171 ** OUTPUTS: None 172 ** RETURN: PRStatus Indication of completion. 173 ** 174 ** SIDE EFFECTS: 175 ** An existing alarm may have its period and rate redefined. The 176 ** additional side effect is that the notifier's epoch is recomputed. 177 ** The first notification delivered by the newly refreshed alarm is 178 ** defined to be 'interval'/'rate' from the time of the reset. 179 ** RESTRICTIONS: 180 ** This function may only be called in the notifier for that alarm. 181 ** MEMORY: N/A. 182 ** ALGORITHM: See PR_SetAlarm(). 183 ***********************************************************************/ 184 NSPR_API(PRStatus) PR_ResetAlarm( 185 PRAlarmID *id, PRIntervalTime period, PRUint32 rate); 186 187 PR_END_EXTERN_C 188 189 #endif /* !defined(pralarm_h) */ 190 191 /* prinrval.h */ 192
