third_party/npapi/npspy/extern/nspr/obsolete/pralarm.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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   3  * The contents of this file are subject to the Mozilla Public
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  12  *
  13  * The Original Code is the Netscape Portable Runtime (NSPR).
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  24  * "GPL"), in which case the provisions of the GPL are applicable
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  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 */