nsprpub/pr/include/obsolete/pralarm.h@44a2da4a2ab2
nsprpub/pr/include/obsolete/pralarm.h
Fri, 16 Jan 2015 04:50:19 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Fri, 16 Jan 2015 04:50:19 +0100
- branch
- TOR_BUG_9701
- changeset 13
- 44a2da4a2ab2
- permissions
- -rw-r--r--
Replace accessor implementation with direct member state manipulation, by
request https://trac.torproject.org/projects/tor/ticket/9701#comment:32
1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 /*
7 ** File: pralarm.h
8 ** Description: API to periodic alarms.
9 **
10 **
11 ** Alarms are defined to invoke some client specified function at
12 ** a time in the future. The notification may be a one time event
13 ** or repeated at a fixed interval. The interval at which the next
14 ** notification takes place may be modified by the client code only
15 ** during the respective notification.
16 **
17 ** The notification is delivered on a thread that is part of the
18 ** alarm context (PRAlarm). The thread will inherit the priority
19 ** of the Alarm creator.
20 **
21 ** Any number of periodic alarms (PRAlarmID) may be created within
22 ** the context of a single alarm (PRAlarm). The notifications will be
23 ** scheduled as close to the desired time as possible.
24 **
25 ** Repeating periodic notifies are expected to run at a fixed rate.
26 ** That rate is expressed as some number of notifies per period where
27 ** the period is much larger than a PRIntervalTime (see prinrval.h).
28 */
30 #if !defined(pralarm_h)
31 #define pralarm_h
33 #include "prtypes.h"
34 #include "prinrval.h"
37 PR_BEGIN_EXTERN_C
39 /**********************************************************************/
40 /************************* TYPES AND CONSTANTS ************************/
41 /**********************************************************************/
43 typedef struct PRAlarm PRAlarm;
44 typedef struct PRAlarmID PRAlarmID;
46 typedef PRBool (PR_CALLBACK *PRPeriodicAlarmFn)(
47 PRAlarmID *id, void *clientData, PRUint32 late);
49 /**********************************************************************/
50 /****************************** FUNCTIONS *****************************/
51 /**********************************************************************/
53 /***********************************************************************
54 ** FUNCTION: PR_CreateAlarm
55 ** DESCRIPTION:
56 ** Create an alarm context.
57 ** INPUTS: void
58 ** OUTPUTS: None
59 ** RETURN: PRAlarm*
60 **
61 ** SIDE EFFECTS:
62 ** This creates an alarm context, which is an object used for subsequent
63 ** notification creations. It also creates a thread that will be used to
64 ** deliver the notifications that are expected to be defined. The client
65 ** is resposible for destroying the context when appropriate.
66 ** RESTRICTIONS:
67 ** None.
68 ** MEMORY: The object (PRAlarm) and a thread to support notifications.
69 ** ALGORITHM: N/A
70 ***********************************************************************/
71 NSPR_API(PRAlarm*) PR_CreateAlarm(void);
73 /***********************************************************************
74 ** FUNCTION: PR_DestroyAlarm
75 ** DESCRIPTION:
76 ** Destroys the context created by PR_CreateAlarm().
77 ** INPUTS: PRAlarm*
78 ** OUTPUTS: None
79 ** RETURN: PRStatus
80 **
81 ** SIDE EFFECTS:
82 ** This destroys the context that was created by PR_CreateAlarm().
83 ** If there are any active alarms (PRAlarmID), they will be cancelled.
84 ** Once that is done, the thread that was used to deliver the alarms
85 ** will be joined.
86 ** RESTRICTIONS:
87 ** None.
88 ** MEMORY: N/A
89 ** ALGORITHM: N/A
90 ***********************************************************************/
91 NSPR_API(PRStatus) PR_DestroyAlarm(PRAlarm *alarm);
93 /***********************************************************************
94 ** FUNCTION: PR_SetAlarm
95 ** DESCRIPTION:
96 ** Creates a periodic notifier that is to be delivered to a specified
97 ** function at some fixed interval.
98 ** INPUTS: PRAlarm *alarm Parent alarm context
99 ** PRIntervalTime period Interval over which the notifies
100 ** are delivered.
101 ** PRUint32 rate The rate within the interval that
102 ** the notifies will be delivered.
103 ** PRPeriodicAlarmFn function Entry point where the notifies
104 ** will be delivered.
105 ** OUTPUTS: None
106 ** RETURN: PRAlarmID* Handle to the notifier just created
107 ** or NULL if the request failed.
108 **
109 ** SIDE EFFECTS:
110 ** A periodic notifier is created. The notifications will be delivered
111 ** by the alarm's internal thread at a fixed interval whose rate is the
112 ** number of interrupts per interval specified. The first notification
113 ** will be delivered as soon as possible, and they will continue until
114 ** the notifier routine indicates that they should cease of the alarm
115 ** context is destroyed (PR_DestroyAlarm).
116 ** RESTRICTIONS:
117 ** None.
118 ** MEMORY: Memory for the notifier object.
119 ** ALGORITHM: The rate at which notifications are delivered are stated
120 ** to be "'rate' notifies per 'interval'". The exact time of
121 ** the notification is computed based on a epoch established
122 ** when the notifier was set. Each notification is delivered
123 ** not ealier than the epoch plus the fixed rate times the
124 ** notification sequence number. Such notifications have the
125 ** potential to be late by not more than 'interval'/'rate'.
126 ** The amount of lateness of one notification is taken into
127 ** account on the next in an attempt to avoid long term slew.
128 ***********************************************************************/
129 NSPR_API(PRAlarmID*) PR_SetAlarm(
130 PRAlarm *alarm, PRIntervalTime period, PRUint32 rate,
131 PRPeriodicAlarmFn function, void *clientData);
133 /***********************************************************************
134 ** FUNCTION: PR_ResetAlarm
135 ** DESCRIPTION:
136 ** Resets an existing alarm.
137 ** INPUTS: PRAlarmID *id Identify of the notifier.
138 ** PRIntervalTime period Interval over which the notifies
139 ** are delivered.
140 ** PRUint32 rate The rate within the interval that
141 ** the notifies will be delivered.
142 ** OUTPUTS: None
143 ** RETURN: PRStatus Indication of completion.
144 **
145 ** SIDE EFFECTS:
146 ** An existing alarm may have its period and rate redefined. The
147 ** additional side effect is that the notifier's epoch is recomputed.
148 ** The first notification delivered by the newly refreshed alarm is
149 ** defined to be 'interval'/'rate' from the time of the reset.
150 ** RESTRICTIONS:
151 ** This function may only be called in the notifier for that alarm.
152 ** MEMORY: N/A.
153 ** ALGORITHM: See PR_SetAlarm().
154 ***********************************************************************/
155 NSPR_API(PRStatus) PR_ResetAlarm(
156 PRAlarmID *id, PRIntervalTime period, PRUint32 rate);
158 PR_END_EXTERN_C
160 #endif /* !defined(pralarm_h) */
162 /* prinrval.h */
