1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "primpl.h"
/**********************************************************************/
/******************************* PRALARM ******************************/
/**********************************************************************/
#include "obsolete/pralarm.h"
struct PRAlarmID { /* typedef'd in pralarm.h */
PRCList list; /* circular list linkage */
PRAlarm *alarm; /* back pointer to owning alarm */
PRPeriodicAlarmFn function; /* function to call for notify */
void *clientData; /* opaque client context */
PRIntervalTime period; /* the client defined period */
PRUint32 rate; /* rate of notification */
PRUint32 accumulator; /* keeps track of # notifies */
PRIntervalTime epoch; /* when timer was started */
PRIntervalTime nextNotify; /* when we'll next do our thing */
PRIntervalTime lastNotify; /* when we last did our thing */
};
typedef enum {alarm_active, alarm_inactive} _AlarmState;
struct PRAlarm { /* typedef'd in pralarm.h */
PRCList timers; /* base of alarm ids list */
PRLock *lock; /* lock used to protect data */
PRCondVar *cond; /* condition that used to wait */
PRThread *notifier; /* thread to deliver notifies */
PRAlarmID *current; /* current alarm being served */
_AlarmState state; /* used to delete the alarm */
};
static PRAlarmID *pr_getNextAlarm(PRAlarm *alarm, PRAlarmID *id)
{
/*
* Puts 'id' back into the sorted list iff it's not NULL.
* Removes the first element from the list and returns it (or NULL).
* List is "assumed" to be short.
*
* NB: Caller is providing locking
*/
PRCList *timer;
PRAlarmID *result = id;
PRIntervalTime now = PR_IntervalNow();
if (!PR_CLIST_IS_EMPTY(&alarm->timers))
{
if (id != NULL) /* have to put this id back in */
{
PRIntervalTime idDelta = now - id->nextNotify;
timer = alarm->timers.next;
do
{
result = (PRAlarmID*)timer;
if ((PRIntervalTime)(now - result->nextNotify) > idDelta)
{
PR_INSERT_BEFORE(&id->list, &alarm->timers);
break;
}
timer = timer->next;
} while (timer != &alarm->timers);
}
result = (PRAlarmID*)(timer = PR_LIST_HEAD(&alarm->timers));
PR_REMOVE_LINK(timer); /* remove it from the list */
}
return result;
} /* pr_getNextAlarm */
static PRIntervalTime pr_PredictNextNotifyTime(PRAlarmID *id)
{
PRIntervalTime delta;
PRFloat64 baseRate = (PRFloat64)id->period / (PRFloat64)id->rate;
PRFloat64 offsetFromEpoch = (PRFloat64)id->accumulator * baseRate;
id->accumulator += 1; /* every call advances to next period */
id->lastNotify = id->nextNotify; /* just keeping track of things */
id->nextNotify = (PRIntervalTime)(offsetFromEpoch + 0.5);
delta = id->nextNotify - id->lastNotify;
return delta;
} /* pr_PredictNextNotifyTime */
static void PR_CALLBACK pr_alarmNotifier(void *arg)
{
/*
* This is the root of the notifier thread. There is one such thread
* for each PRAlarm. It may service an arbitrary (though assumed to be
* small) number of alarms using the same thread and structure. It
* continues to run until the alarm is destroyed.
*/
PRAlarmID *id = NULL;
PRAlarm *alarm = (PRAlarm*)arg;
enum {notify, abort, scan} why = scan;
while (why != abort)
{
PRIntervalTime pause;
PR_Lock(alarm->lock);
while (why == scan)
{
alarm->current = NULL; /* reset current id */
if (alarm->state == alarm_inactive) why = abort; /* we're toast */
else if (why == scan) /* the dominant case */
{
id = pr_getNextAlarm(alarm, id); /* even if it's the same */
if (id == NULL) /* there are no alarms set */
(void)PR_WaitCondVar(alarm->cond, PR_INTERVAL_NO_TIMEOUT);
else
{
pause = id->nextNotify - (PR_IntervalNow() - id->epoch);
if ((PRInt32)pause <= 0) /* is this one's time up? */
{
why = notify; /* set up to do our thing */
alarm->current = id; /* id we're about to schedule */
}
else
(void)PR_WaitCondVar(alarm->cond, pause); /* dally */
}
}
}
PR_Unlock(alarm->lock);
if (why == notify)
{
(void)pr_PredictNextNotifyTime(id);
if (!id->function(id, id->clientData, ~pause))
{
/*
* Notified function decided not to continue. Free
* the alarm id to make sure it doesn't get back on
* the list.
*/
PR_DELETE(id); /* free notifier object */
id = NULL; /* so it doesn't get back into the list */
}
why = scan; /* so we can cycle through the loop again */
}
}
} /* pr_alarm_notifier */
PR_IMPLEMENT(PRAlarm*) PR_CreateAlarm(void)
{
PRAlarm *alarm = PR_NEWZAP(PRAlarm);
if (alarm != NULL)
{
if ((alarm->lock = PR_NewLock()) == NULL) goto done;
if ((alarm->cond = PR_NewCondVar(alarm->lock)) == NULL) goto done;
alarm->state = alarm_active;
PR_INIT_CLIST(&alarm->timers);
alarm->notifier = PR_CreateThread(
PR_USER_THREAD, pr_alarmNotifier, alarm,
PR_GetThreadPriority(PR_GetCurrentThread()),
PR_LOCAL_THREAD, PR_JOINABLE_THREAD, 0);
if (alarm->notifier == NULL) goto done;
}
return alarm;
done:
if (alarm->cond != NULL) PR_DestroyCondVar(alarm->cond);
if (alarm->lock != NULL) PR_DestroyLock(alarm->lock);
PR_DELETE(alarm);
return NULL;
} /* CreateAlarm */
PR_IMPLEMENT(PRStatus) PR_DestroyAlarm(PRAlarm *alarm)
{
PRStatus rv;
PR_Lock(alarm->lock);
alarm->state = alarm_inactive;
rv = PR_NotifyCondVar(alarm->cond);
PR_Unlock(alarm->lock);
if (rv == PR_SUCCESS)
rv = PR_JoinThread(alarm->notifier);
if (rv == PR_SUCCESS)
{
PR_DestroyCondVar(alarm->cond);
PR_DestroyLock(alarm->lock);
PR_DELETE(alarm);
}
return rv;
} /* PR_DestroyAlarm */
PR_IMPLEMENT(PRAlarmID*) PR_SetAlarm(
PRAlarm *alarm, PRIntervalTime period, PRUint32 rate,
PRPeriodicAlarmFn function, void *clientData)
{
/*
* Create a new periodic alarm an existing current structure.
* Set up the context and compute the first notify time (immediate).
* Link the new ID into the head of the list (since it's notifying
* immediately).
*/
PRAlarmID *id = PR_NEWZAP(PRAlarmID);
if (!id)
return NULL;
id->alarm = alarm;
PR_INIT_CLIST(&id->list);
id->function = function;
id->clientData = clientData;
id->period = period;
id->rate = rate;
id->epoch = id->nextNotify = PR_IntervalNow();
(void)pr_PredictNextNotifyTime(id);
PR_Lock(alarm->lock);
PR_INSERT_BEFORE(&id->list, &alarm->timers);
PR_NotifyCondVar(alarm->cond);
PR_Unlock(alarm->lock);
return id;
} /* PR_SetAlarm */
PR_IMPLEMENT(PRStatus) PR_ResetAlarm(
PRAlarmID *id, PRIntervalTime period, PRUint32 rate)
{
/*
* Can only be called from within the notify routine. Doesn't
* need locking because it can only be called from within the
* notify routine.
*/
if (id != id->alarm->current)
return PR_FAILURE;
id->period = period;
id->rate = rate;
id->accumulator = 1;
id->epoch = PR_IntervalNow();
(void)pr_PredictNextNotifyTime(id);
return PR_SUCCESS;
} /* PR_ResetAlarm */
|
