summaryrefslogtreecommitdiffstats
path: root/ldap/servers/slapd/eventq.c
blob: 8909e074aab23043e7388d58c9b0f8fb2fc9a0d7 (plain)
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
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
/** BEGIN COPYRIGHT BLOCK
 * This Program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation; version 2 of the License.
 * 
 * This Program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this Program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place, Suite 330, Boston, MA 02111-1307 USA.
 * 
 * In addition, as a special exception, Red Hat, Inc. gives You the additional
 * right to link the code of this Program with code not covered under the GNU
 * General Public License ("Non-GPL Code") and to distribute linked combinations
 * including the two, subject to the limitations in this paragraph. Non-GPL Code
 * permitted under this exception must only link to the code of this Program
 * through those well defined interfaces identified in the file named EXCEPTION
 * found in the source code files (the "Approved Interfaces"). The files of
 * Non-GPL Code may instantiate templates or use macros or inline functions from
 * the Approved Interfaces without causing the resulting work to be covered by
 * the GNU General Public License. Only Red Hat, Inc. may make changes or
 * additions to the list of Approved Interfaces. You must obey the GNU General
 * Public License in all respects for all of the Program code and other code used
 * in conjunction with the Program except the Non-GPL Code covered by this
 * exception. If you modify this file, you may extend this exception to your
 * version of the file, but you are not obligated to do so. If you do not wish to
 * provide this exception without modification, you must delete this exception
 * statement from your version and license this file solely under the GPL without
 * exception. 
 * 
 * 
 * Copyright (C) 2001 Sun Microsystems, Inc. Used by permission.
 * Copyright (C) 2005 Red Hat, Inc.
 * All rights reserved.
 * END COPYRIGHT BLOCK **/

/* ********************************************************
eventq.c - Event queue/scheduling system.

There are 3 publicly-accessible entry points:

slapi_eq_once(): cause an event to happen exactly once
slapi_eq_repeat(): cause an event to happen repeatedly
slapi_eq_cancel(): cancel a pending event

There is also an initialization point which must be
called by the server to initialize the event queue system:
eq_start(), and an entry point used to shut down the system:
eq_stop().
*********************************************************** */

#include "slap.h"
#include "prlock.h"
#include "prcvar.h"
#include "prinit.h"

/*
 * Private definition of slapi_eq_context. Only this
 * module (eventq.c) should know about the layout of
 * this structure.
 */
typedef struct _slapi_eq_context {
	time_t ec_when;
	time_t ec_interval;
	slapi_eq_fn_t ec_fn;
	void *ec_arg;
	Slapi_Eq_Context ec_id;
	struct _slapi_eq_context *ec_next;
} slapi_eq_context;

/*
 * Definition of the event queue.
 */ 
typedef struct _event_queue {
	PRLock *eq_lock;
	PRCondVar *eq_cv;
	slapi_eq_context *eq_queue;
} event_queue;

/*
 * The event queue itself.
 */
static event_queue eqs = {0};
static event_queue *eq = &eqs;

/*
 * Thread ID of the main thread loop
 */
static PRThread *eq_loop_tid = NULL;

/*
 * Flags used to control startup/shutdown of the event queue
 */
static int eq_running = 0;
static int eq_stopped = 0;
static int eq_initialized = 0;
PRLock *ss_lock = NULL;
PRCondVar *ss_cv = NULL;
PRCallOnceType init_once = {0};

/* Forward declarations */
static slapi_eq_context *eq_new(slapi_eq_fn_t fn, void *arg,
		time_t when, unsigned long interval);
static void eq_enqueue(slapi_eq_context *newec);
static slapi_eq_context *eq_dequeue(time_t now);
static PRStatus eq_create(void);


/* ******************************************************** */



/*
 * slapi_eq_once: cause an event to happen exactly once.
 * 
 * Arguments:
 *  fn: the function to call
 *  arg: an argument to pass to the called function
 *  when: the time that the function should be called
 * Returns:
 *  slapi_eq_context - a handle to an opaque object which
 *  the caller can use to refer to this particular scheduled
 *  event.
 */
Slapi_Eq_Context
slapi_eq_once(slapi_eq_fn_t fn, void *arg, time_t when)
{
	slapi_eq_context *tmp;
	PR_ASSERT(eq_initialized);
	if (!eq_stopped) {
		
		Slapi_Eq_Context id;

		tmp = eq_new(fn, arg, when, 0UL);
		id = tmp->ec_id;

		eq_enqueue(tmp);

		/* After this point, <tmp> may have      */
		/* been freed, depending on the thread   */
		/* scheduling. Too bad			 */

		slapi_log_error(SLAPI_LOG_HOUSE, NULL,
				"added one-time event id %p at time %ld\n",
				id, when);
		return(id);
	}
	return NULL; /* JCM - Not sure if this should be 0 or something else. */
}
		



/*
 * slapi_eq_repeat: cause an event to happen repeatedly.
 * 
 * Arguments:
 *  fn: the function to call
 *  arg: an argument to pass to the called function
 *  when: the time that the function should first be called
 *  interval: the amount of time (in milliseconds) between
 *            successive calls to the function
 * Returns:
 *  slapi_eq_context - a handle to an opaque object which
 *  the caller can use to refer to this particular scheduled
 */
Slapi_Eq_Context
slapi_eq_repeat(slapi_eq_fn_t fn, void *arg, time_t when, unsigned long interval)
{
	slapi_eq_context *tmp ;
	PR_ASSERT(eq_initialized);
	if (!eq_stopped) {
		tmp = eq_new(fn, arg, when, interval);
		eq_enqueue(tmp);
		slapi_log_error(SLAPI_LOG_HOUSE, NULL,
				"added repeating event id %p at time %ld, interval %lu\n",
				tmp->ec_id, when, interval);
		return(tmp->ec_id);
	}
	return NULL; /* JCM - Not sure if this should be 0 or something else. */
}



/*
 * slapi_eq_cancel: cancel a pending event.
 * Arguments:
 *  ctx: the context of the event which should be de-scheduled
 */
int
slapi_eq_cancel(Slapi_Eq_Context ctx) 
{
	slapi_eq_context **p, *tmp = NULL;
	int found = 0;

	PR_ASSERT(eq_initialized);
	if (!eq_stopped) {
		PR_Lock(eq->eq_lock);
		p = &(eq->eq_queue);
		while (!found && *p != NULL) {		
			if ((*p)->ec_id == ctx) {
				tmp = *p;
				*p = (*p)->ec_next;
				slapi_ch_free((void**)&tmp);
				found = 1;
			} else {
				p = &((*p)->ec_next);
			}
		}
		PR_Unlock(eq->eq_lock);
	}
	slapi_log_error(SLAPI_LOG_HOUSE, NULL,
			"cancellation of event id %p requested: %s\n",
			ctx, found ? "cancellation succeeded" : "event not found");
	return found;
}




/*
 * Construct a new ec structure
 */
static slapi_eq_context *
eq_new(slapi_eq_fn_t fn, void *arg, time_t when, unsigned long interval)
{
	slapi_eq_context *retptr = (slapi_eq_context *)slapi_ch_calloc(1, sizeof(slapi_eq_context));
	time_t now;

	retptr->ec_fn = fn;
	retptr->ec_arg = arg;
	now = current_time();
	retptr->ec_when = when < now ? now : when;
	retptr->ec_interval = interval == 0UL ? 0UL : (interval + 999) / 1000;
	retptr->ec_id = (Slapi_Eq_Context)retptr;
	return retptr;
}




/*
 * Add a new event to the event queue.
 */
static void
eq_enqueue(slapi_eq_context *newec)
{
	slapi_eq_context **p;

	PR_ASSERT(NULL != newec);
	PR_Lock(eq->eq_lock);
	/* Insert <newec> in order (sorted by start time) in the list */
	for (p = &(eq->eq_queue); *p != NULL; p = &((*p)->ec_next)) {
		if ((*p)->ec_when > newec->ec_when) {
			break;
		}
	}
	if (NULL != *p) {
		newec->ec_next = *p;
	} else {
		newec->ec_next = NULL;
	}
	*p = newec;
	PR_NotifyCondVar(eq->eq_cv); /* wake up scheduler thread */
	PR_Unlock(eq->eq_lock);
}




/*
 * If there is an event in the queue scheduled at time
 * <now> or before, dequeue it and return a pointer
 * to it. Otherwise, return NULL.
 */
static slapi_eq_context *
eq_dequeue(time_t now)
{
	slapi_eq_context *retptr = NULL;

	PR_Lock(eq->eq_lock);
	if (NULL != eq->eq_queue && eq->eq_queue->ec_when <= now) {
		retptr = eq->eq_queue;
		eq->eq_queue = retptr->ec_next;
	}
	PR_Unlock(eq->eq_lock);
	return retptr;
}



/*
 * Call all events which are due to run.
 * Note that if we've missed a schedule
 * opportunity, we don't try to catch up
 * by calling the function repeatedly.
 */
static void
eq_call_all()
{
	slapi_eq_context *p;

	while ((p = eq_dequeue(current_time())) != NULL) {
		/* Call the scheduled function */
		p->ec_fn(p->ec_when, p->ec_arg);
		slapi_log_error(SLAPI_LOG_HOUSE, NULL,
				"Event id %p called at %ld (scheduled for %ld)\n",
				p->ec_id, current_time(), p->ec_when);
		if (0UL != p->ec_interval) {
			/* This is a repeating event. Requeue it. */
			do {
				p->ec_when += p->ec_interval;
			} while (p->ec_when < current_time());
			eq_enqueue(p);
		} else {
			slapi_ch_free((void **)&p);
		}
	}
}




/*
 * The main event queue loop.
 */
#define WORK_AVAILABLE ((NULL != eq->eq_queue) && (eq->eq_queue->ec_when <= current_time()))

static void
eq_loop(void *arg)
{
	while (eq_running) {
		PRIntervalTime timeout;
		int until;
		PR_Lock(eq->eq_lock);
		while (!WORK_AVAILABLE) {
			if (!eq_running) {
				PR_Unlock(eq->eq_lock);
				goto bye;
			}
			/* Compute new timeout */
			if (NULL != eq->eq_queue) {
				until = eq->eq_queue->ec_when - current_time();
				timeout = PR_SecondsToInterval(until);
			} else {
				timeout = PR_INTERVAL_NO_TIMEOUT;
			}
			PR_WaitCondVar(eq->eq_cv, timeout);
		}
		/* There is some work to do */
		PR_Unlock(eq->eq_lock);
		eq_call_all();
	}
bye:
	eq_stopped = 1;
	PR_Lock(ss_lock);
	PR_NotifyAllCondVar(ss_cv);
	PR_Unlock(ss_lock);
}



/*
 * Allocate and initialize the event queue structures.
 */
static PRStatus
eq_create(void)
{
	PR_ASSERT(NULL == eq->eq_lock);
	if ((eq->eq_lock = PR_NewLock()) == NULL) {
		slapi_log_error(SLAPI_LOG_FATAL, NULL, "eq_start PR_NewLock failed\n");
		exit(1);
	}
	if ((eq->eq_cv = PR_NewCondVar(eq->eq_lock)) == NULL) {
		slapi_log_error(SLAPI_LOG_FATAL, NULL, "eq_start PR_NewCondVar failed\n");
		exit(1);
	}
	if ((ss_lock = PR_NewLock()) == NULL) {
		slapi_log_error(SLAPI_LOG_FATAL, NULL, "eq_start PR_NewLock failed\n");
		exit(1);
	}
	if ((ss_cv = PR_NewCondVar(ss_lock)) == NULL) {
		slapi_log_error(SLAPI_LOG_FATAL, NULL, "eq_start PR_NewCondVar failed\n");
		exit(1);
	}
	eq->eq_queue = NULL;
	eq_initialized = 1;
	return PR_SUCCESS;
}





/*
 * eq_start: start the event queue system. 
 * 
 * This should be called exactly once. It will start a
 * thread which wakes up periodically and schedules events.
 */
void
eq_start()
{
	PR_ASSERT(eq_initialized);
	eq_running = 1;
	if ((eq_loop_tid = PR_CreateThread(PR_USER_THREAD, (VFP)eq_loop,
			NULL, PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD, PR_JOINABLE_THREAD,
			SLAPD_DEFAULT_THREAD_STACKSIZE)) == NULL) {
		slapi_log_error(SLAPI_LOG_FATAL, NULL, "eq_init PR_CreateThread failed\n");
		exit(1);
	}
	slapi_log_error(SLAPI_LOG_HOUSE, NULL, "event queue services have started\n");
}



/*
 * eq_init: initialize the event queue system.
 *
 * This function should be called early in server startup.
 * Once it has been called, the event queue will queue
 * events, but will not fire any events. Once all of the
 * server plugins have been started, the eq_start()
 * function should be called, and events will then start
 * to fire.
 */
void
eq_init()
{
	if (!eq_initialized) {
		PR_CallOnce(&init_once, eq_create);
	}
}



/*
 * eq_stop: shut down the event queue system.
 * Does not return until event queue is fully
 * shut down.
 */
void
eq_stop()
{
    slapi_eq_context *p, *q;

    if ( NULL == eq || NULL == eq->eq_lock ) {    /* never started */
        eq_stopped = 1;
        return;
    }

    eq_stopped = 0;
    eq_running = 0;
    /* 
     * Signal the eq thread function to stop, and wait until
     * it acknowledges by setting eq_stopped.
     */
    while (!eq_stopped) {
        PR_Lock(eq->eq_lock);
        PR_NotifyAllCondVar(eq->eq_cv);
        PR_Unlock(eq->eq_lock);
        PR_Lock(ss_lock);
        PR_WaitCondVar(ss_cv, PR_MillisecondsToInterval(100));
        PR_Unlock(ss_lock);
    }
    (void)PR_JoinThread(eq_loop_tid);
    /*
     * XXXggood we don't free the actual event queue data structures.
     * This is intentional, to allow enqueueing/cancellation of events
     * even after event queue services have shut down (these are no-ops).
     * The downside is that the event queue can't be stopped and restarted
     * easily.
     */
    PR_Lock(eq->eq_lock);
    p = eq->eq_queue;
    while (p != NULL) {
         q = p->ec_next;
         slapi_ch_free((void**)&p);
        /* Some ec_arg could get leaked here in shutdown (e.g., replica_name)
         * This can be fixed by specifying a flag when the context is queued.
         * [After 6.2]
         */
         p = q;
    }
    PR_Unlock(eq->eq_lock);
    slapi_log_error(SLAPI_LOG_HOUSE, NULL, "event queue services have shut down\n");
}

/*
 * return arg (ec_arg) only if the context is in the event queue
 */
void *
slapi_eq_get_arg ( Slapi_Eq_Context ctx )
{
    slapi_eq_context **p;

    PR_ASSERT(eq_initialized);
    if (!eq_stopped) {
        PR_Lock(eq->eq_lock);
        p = &(eq->eq_queue);
        while (p && *p != NULL) {        
            if ((*p)->ec_id == ctx) {
                PR_Unlock(eq->eq_lock);
                return (*p)->ec_arg;
            } else {
                p = &((*p)->ec_next);
            }
        }
        PR_Unlock(eq->eq_lock);
    }
    return NULL;
}