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1.1 root 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 */
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