aboutsummaryrefslogtreecommitdiffstats
path: root/erts/emulator/beam/erl_bif_timer.c
blob: cf58e6cb2b1b8a64837b6bd2f37143fbd8c166f0 (plain) (blame)
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
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 2005-2012. All Rights Reserved.
 *
 * The contents of this file are subject to the Erlang Public License,
 * Version 1.1, (the "License"); you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * Erlang Public License along with this software. If not, it can be
 * retrieved online at http://www.erlang.org/.
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * %CopyrightEnd%
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "erl_bif_timer.h"
#include "global.h"
#include "bif.h"
#include "error.h"
#include "big.h"
#include "erl_thr_progress.h"

/****************************************************************************
** BIF Timer support
****************************************************************************/

#define BTM_FLG_SL_TIMER	(((Uint32) 1) << 0)
#define BTM_FLG_CANCELED	(((Uint32) 1) << 1)
#define BTM_FLG_HEAD		(((Uint32) 1) << 2)
#define BTM_FLG_BYNAME		(((Uint32) 1) << 3)
#define BTM_FLG_WRAP		(((Uint32) 1) << 4)

struct ErtsBifTimer_ {
    struct {
	union {
	    ErtsBifTimer **head;
	    ErtsBifTimer *prev;
	} u;
	ErtsBifTimer *next;
    } tab;
    union {
	Eterm name;
	struct {
	    ErtsBifTimer *prev;
	    ErtsBifTimer *next;
	    Process *ess;
	} proc;
    } receiver;
    ErlTimer tm;
    ErlHeapFragment* bp;
    Uint32 flags;
    Eterm message;
    Uint32 ref_numbers[ERTS_REF_NUMBERS];
};

#ifdef SMALL_MEMORY
#define TIMER_HASH_VEC_SZ	3331
#define BTM_PREALC_SZ		10
#else
#define TIMER_HASH_VEC_SZ	10007
#define BTM_PREALC_SZ		100
#endif
static ErtsBifTimer **bif_timer_tab;  
static Uint no_bif_timers;


static erts_smp_rwmtx_t bif_timer_lock;

#define erts_smp_safe_btm_rwlock(P, L) \
	safe_btm_lock((P), (L), 1)
#define erts_smp_safe_btm_rlock(P, L) \
	safe_btm_lock((P), (L), 0)
#define erts_smp_btm_rwlock() \
	erts_smp_rwmtx_rwlock(&bif_timer_lock)
#define erts_smp_btm_tryrwlock() \
	erts_smp_rwmtx_tryrwlock(&bif_timer_lock)
#define erts_smp_btm_rwunlock() \
	erts_smp_rwmtx_rwunlock(&bif_timer_lock)
#define erts_smp_btm_rlock() \
	erts_smp_rwmtx_rlock(&bif_timer_lock)
#define erts_smp_btm_tryrlock() \
	erts_smp_rwmtx_tryrlock(&bif_timer_lock)
#define erts_smp_btm_runlock() \
	erts_smp_rwmtx_runlock(&bif_timer_lock)
#define erts_smp_btm_lock_init() \
	erts_smp_rwmtx_init(&bif_timer_lock, "bif_timers")


static ERTS_INLINE int
safe_btm_lock(Process *c_p, ErtsProcLocks c_p_locks, int rw_lock)
{
    ASSERT(c_p && c_p_locks);
#ifdef ERTS_SMP
    if ((rw_lock ? erts_smp_btm_tryrwlock() : erts_smp_btm_tryrlock()) != EBUSY)
	return 0;
    erts_smp_proc_unlock(c_p, c_p_locks);
    if (rw_lock)
	erts_smp_btm_rwlock();
    else
	erts_smp_btm_rlock();
    erts_smp_proc_lock(c_p, c_p_locks);
    if (ERTS_PROC_IS_EXITING(c_p)) {
	if (rw_lock)
	    erts_smp_btm_rwunlock();
	else
	    erts_smp_btm_runlock();
	return 1;
    }
#endif
    return 0;
}

ERTS_SCHED_PREF_PALLOC_IMPL(btm_pre, ErtsBifTimer, BTM_PREALC_SZ)

static ERTS_INLINE int
get_index(Uint32 *ref_numbers, Uint32 len)
{
    Uint32 hash;
    /* len can potentially be larger than ERTS_REF_NUMBERS
       if it has visited another node... */
    if (len > ERTS_REF_NUMBERS)
	len = ERTS_REF_NUMBERS;

#if ERTS_REF_NUMBERS != 3
#error "ERTS_REF_NUMBERS changed. Update me..."
#endif
    switch (len) {
    case 3: if (!ref_numbers[2]) len = 2;
    case 2: if (!ref_numbers[1]) len = 1;
    default:  break;
    }

    ASSERT(1 <= len && len <= ERTS_REF_NUMBERS);

    hash = block_hash((byte *) ref_numbers, len * sizeof(Uint32), 0x08d12e65);
    return (int) (hash % ((Uint32) TIMER_HASH_VEC_SZ));
}

static Eterm
create_ref(Uint *hp, Uint32 *ref_numbers, Uint32 len)
{
    Uint32 *datap;
    int i;


    if (len > ERTS_MAX_REF_NUMBERS) {
	/* Such large refs should no be able to appear in the emulator */
	erl_exit(1, "%s:%d: Internal error\n", __FILE__, __LINE__);
    }

#if defined(ARCH_64) && !HALFWORD_HEAP
    hp[0] = make_ref_thing_header(len/2 + 1);
    datap = (Uint32 *) &hp[1];
    *(datap++) = len;
#else
    hp[0] = make_ref_thing_header(len);
    datap = (Uint32 *) &hp[1];
#endif

    for (i = 0; i < len; i++)
	datap[i] = ref_numbers[i];

    return make_internal_ref(hp);
}

static int
eq_non_standard_ref_numbers(Uint32 *rn1, Uint32 len1, Uint32 *rn2, Uint32 len2)
{
#if defined(ARCH_64) && !HALFWORD_HEAP
#define MAX_REF_HEAP_SZ (1+(ERTS_MAX_REF_NUMBERS/2+1))
#else
#define MAX_REF_HEAP_SZ (1+ERTS_MAX_REF_NUMBERS)
#endif
    DeclareTmpHeapNoproc(r1_hp,(MAX_REF_HEAP_SZ * 2));
    Eterm *r2_hp = r1_hp +MAX_REF_HEAP_SZ;

    return eq(create_ref(r1_hp, rn1, len1), create_ref(r2_hp, rn2, len2));
#undef MAX_REF_HEAP_SZ
}

static ERTS_INLINE int
eq_ref_numbers(Uint32 *rn1, Uint32 len1, Uint32 *rn2, Uint32 len2)
{
    int res;
    if (len1 != ERTS_REF_NUMBERS || len2 != ERTS_REF_NUMBERS) {
	/* Can potentially happen, but will never... */
	return eq_non_standard_ref_numbers(rn1, len1, rn2, len2);
    }

#if ERTS_REF_NUMBERS != 3
#error "ERTS_REF_NUMBERS changed. Update me..."
#endif
    res = rn1[0] == rn2[0] && rn1[1] == rn2[1] && rn1[2] == rn2[2];

    ASSERT(res
	   ? eq_non_standard_ref_numbers(rn1, len1, rn2, len2)
	   : !eq_non_standard_ref_numbers(rn1, len1, rn2, len2));

    return res;
}

static ERTS_INLINE ErtsBifTimer *
tab_find(Eterm ref)
{
    Uint32 *ref_numbers = internal_ref_numbers(ref);
    Uint32 ref_numbers_len = internal_ref_no_of_numbers(ref);
    int ix = get_index(ref_numbers, ref_numbers_len);
    ErtsBifTimer* btm;

    for (btm = bif_timer_tab[ix]; btm; btm = btm->tab.next)
	if (eq_ref_numbers(ref_numbers, ref_numbers_len,
			   btm->ref_numbers, ERTS_REF_NUMBERS))
	    return btm;
    return NULL;
}

static ERTS_INLINE void
tab_remove(ErtsBifTimer* btm)
{
    if (btm->flags & BTM_FLG_HEAD) {
	*btm->tab.u.head = btm->tab.next;
	if (btm->tab.next) {
	    btm->tab.next->flags |= BTM_FLG_HEAD;
	    btm->tab.next->tab.u.head = btm->tab.u.head;
	}
    }
    else {
	btm->tab.u.prev->tab.next = btm->tab.next;
	if (btm->tab.next)
	    btm->tab.next->tab.u.prev = btm->tab.u.prev;
    }
    btm->flags |= BTM_FLG_CANCELED;
    ASSERT(no_bif_timers > 0);
    no_bif_timers--;
}

static ERTS_INLINE void
tab_insert(ErtsBifTimer* btm)
{
    int ix = get_index(btm->ref_numbers, ERTS_REF_NUMBERS);
    ErtsBifTimer* btm_list = bif_timer_tab[ix];

    if (btm_list) {
	btm_list->flags &= ~BTM_FLG_HEAD;
	btm_list->tab.u.prev = btm;
    }

    btm->flags |= BTM_FLG_HEAD;
    btm->tab.u.head = &bif_timer_tab[ix];
    btm->tab.next = btm_list;
    bif_timer_tab[ix] = btm;
    no_bif_timers++;
}

static ERTS_INLINE void
link_proc(Process *p, ErtsBifTimer* btm)
{
    btm->receiver.proc.ess = p;
    btm->receiver.proc.prev = NULL;
    btm->receiver.proc.next = p->u.bif_timers;
    if (p->u.bif_timers)	
	p->u.bif_timers->receiver.proc.prev = btm;
    p->u.bif_timers = btm;
}

static ERTS_INLINE void
unlink_proc(ErtsBifTimer* btm)
{
    if (btm->receiver.proc.prev)
	btm->receiver.proc.prev->receiver.proc.next = btm->receiver.proc.next;
    else
	btm->receiver.proc.ess->u.bif_timers = btm->receiver.proc.next;
    if (btm->receiver.proc.next)
	btm->receiver.proc.next->receiver.proc.prev = btm->receiver.proc.prev;
}

static void
bif_timer_cleanup(ErtsBifTimer* btm)
{
    ASSERT(btm);

    if (btm->bp)
	free_message_buffer(btm->bp);

    if (!btm_pre_free(btm)) {
	if (btm->flags & BTM_FLG_SL_TIMER)
	    erts_free(ERTS_ALC_T_SL_BIF_TIMER, (void *) btm);
	else
	    erts_free(ERTS_ALC_T_LL_BIF_TIMER, (void *) btm);
    }
}

static void
bif_timer_timeout(ErtsBifTimer* btm)
{
    ASSERT(btm);


    erts_smp_btm_rwlock();

    if (btm->flags & BTM_FLG_CANCELED) {
    /*
     * A concurrent cancel is ongoing. Do not send the timeout message,
     * but cleanup here since the cancel call-back won't be called.
     */
#ifndef ERTS_SMP
	ASSERT(0);
#endif
    }
    else {
	ErtsProcLocks rp_locks = 0;
	Process* rp;

	tab_remove(btm);

	ASSERT(!erts_get_current_process());

	if (btm->flags & BTM_FLG_BYNAME)
	    rp = erts_whereis_process(NULL, 0, btm->receiver.name, 0, 0);
	else {
	    rp = btm->receiver.proc.ess;
	    unlink_proc(btm);
	}

	if (rp) {
	    Eterm message;
	    ErlHeapFragment *bp;

	    bp = btm->bp;
	    btm->bp = NULL; /* Prevent cleanup of message buffer... */

	    if (!(btm->flags & BTM_FLG_WRAP))
		message = btm->message;
	    else {
#if ERTS_REF_NUMBERS != 3
#error "ERTS_REF_NUMBERS changed. Update me..."
#endif
		Eterm ref;
		Uint *hp;
		Uint wrap_size = REF_THING_SIZE + 4;
		message = btm->message;

		if (!bp) {
		    ErlOffHeap *ohp;
		    ASSERT(is_immed(message));
		    hp = erts_alloc_message_heap(wrap_size,
						 &bp,
						 &ohp,
						 rp,
						 &rp_locks);
		} else {
		    Eterm old_size = bp->used_size;
		    bp = erts_resize_message_buffer(bp, old_size + wrap_size,
						    &message, 1);
		    hp = &bp->mem[0] + old_size;
		}

		write_ref_thing(hp,
				btm->ref_numbers[0],
				btm->ref_numbers[1],
				btm->ref_numbers[2]);
		ref = make_internal_ref(hp);
		hp += REF_THING_SIZE;
		message = TUPLE3(hp, am_timeout, ref, message);
	    }

	    erts_queue_message(rp, &rp_locks, bp, message, NIL
#ifdef USE_VM_PROBES
			       , NIL
#endif
			       );
	    erts_smp_proc_unlock(rp, rp_locks);
	}
    }

    erts_smp_btm_rwunlock();

    bif_timer_cleanup(btm);
}

static Eterm
setup_bif_timer(Uint32 xflags,
		Process *c_p,
		Eterm time,
		Eterm receiver,
		Eterm message)
{
    Process *rp;
    ErtsBifTimer* btm;
    Uint timeout;
    Eterm ref;
    Uint32 *ref_numbers;
    
    if (!term_to_Uint(time, &timeout))
	return THE_NON_VALUE;
#if defined(ARCH_64) && !HALFWORD_HEAP
    if ((timeout >> 32) != 0)
	return THE_NON_VALUE;
#endif
    if (is_not_internal_pid(receiver) && is_not_atom(receiver))
	return THE_NON_VALUE;

    ref = erts_make_ref(c_p);

    if (is_atom(receiver))
	rp = NULL;
    else {
	rp = erts_pid2proc(c_p, ERTS_PROC_LOCK_MAIN,
			   receiver, ERTS_PROC_LOCK_MSGQ);
	if (!rp)
	    return ref;
    }

    if (timeout < ERTS_ALC_MIN_LONG_LIVED_TIME) {
	if (timeout < 1000) {
	    btm = btm_pre_alloc();
	    if (!btm)
		goto sl_timer_alloc;
	    btm->flags = 0;
	}
	else {
	sl_timer_alloc:
	    btm = (ErtsBifTimer *) erts_alloc(ERTS_ALC_T_SL_BIF_TIMER,
					      sizeof(ErtsBifTimer));
	    btm->flags = BTM_FLG_SL_TIMER;
	}
    }
    else {
	btm = (ErtsBifTimer *) erts_alloc(ERTS_ALC_T_LL_BIF_TIMER,
					 sizeof(ErtsBifTimer));
	btm->flags = 0;
    }

    if (rp) {
	link_proc(rp, btm);
	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_MSGQ);
    }
    else {
	ASSERT(is_atom(receiver));
	btm->receiver.name = receiver;
	btm->flags |= BTM_FLG_BYNAME;
    }

    btm->flags |= xflags;

    ref_numbers = internal_ref_numbers(ref);
    ASSERT(internal_ref_no_of_numbers(ref) == 3);
#if ERTS_REF_NUMBERS != 3
#error "ERTS_REF_NUMBERS changed. Update me..."
#endif
    btm->ref_numbers[0] = ref_numbers[0];
    btm->ref_numbers[1] = ref_numbers[1];
    btm->ref_numbers[2] = ref_numbers[2];

    ASSERT(eq_ref_numbers(btm->ref_numbers, ERTS_REF_NUMBERS,
			  ref_numbers, ERTS_REF_NUMBERS));

    if (is_immed(message)) {
	btm->bp = NULL;
	btm->message = message;
    }
    else {
	ErlHeapFragment* bp;
	Eterm* hp;
	Uint size;

	size = size_object(message);
	btm->bp = bp = new_message_buffer(size);
	hp = bp->mem;
	btm->message = copy_struct(message, size, &hp, &bp->off_heap);
    }

    tab_insert(btm);
    ASSERT(btm == tab_find(ref));
    btm->tm.active = 0; /* MUST be initalized */
    erts_set_timer(&btm->tm,
		  (ErlTimeoutProc) bif_timer_timeout,
		  (ErlCancelProc) bif_timer_cleanup,
		  (void *) btm,
		  timeout);
    return ref;
}

/* send_after(Time, Pid, Message) -> Ref */
BIF_RETTYPE send_after_3(BIF_ALIST_3)
{
    Eterm res;

    if (erts_smp_safe_btm_rwlock(BIF_P, ERTS_PROC_LOCK_MAIN))
	ERTS_BIF_EXITED(BIF_P);

    res = setup_bif_timer(0, BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3);

    erts_smp_btm_rwunlock();

    if (is_non_value(res)) {
	BIF_ERROR(BIF_P, BADARG);
    }
    else {
	ASSERT(is_internal_ref(res));
	BIF_RET(res);
    }
}

/* start_timer(Time, Pid, Message) -> Ref */
BIF_RETTYPE start_timer_3(BIF_ALIST_3)
{
    Eterm res;

    if (erts_smp_safe_btm_rwlock(BIF_P, ERTS_PROC_LOCK_MAIN))
	ERTS_BIF_EXITED(BIF_P);

    res = setup_bif_timer(BTM_FLG_WRAP, BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3);

    erts_smp_btm_rwunlock();

    if (is_non_value(res)) {
	BIF_ERROR(BIF_P, BADARG);
    }
    else {
	ASSERT(is_internal_ref(res));
	BIF_RET(res);
    }
}

/* cancel_timer(Ref) -> false | RemainingTime */
BIF_RETTYPE cancel_timer_1(BIF_ALIST_1)
{
    Eterm res;
    ErtsBifTimer *btm;

    if (is_not_internal_ref(BIF_ARG_1)) {
	if (is_ref(BIF_ARG_1)) {
	    BIF_RET(am_false);
	}
	BIF_ERROR(BIF_P, BADARG);
    }

    if (erts_smp_safe_btm_rwlock(BIF_P, ERTS_PROC_LOCK_MAIN))
	ERTS_BIF_EXITED(BIF_P);

    btm = tab_find(BIF_ARG_1);
    if (!btm || btm->flags & BTM_FLG_CANCELED) {
	erts_smp_btm_rwunlock();
	res = am_false;
    }
    else {
	Uint left = erts_time_left(&btm->tm);
	if (!(btm->flags & BTM_FLG_BYNAME)) {
	    erts_smp_proc_lock(btm->receiver.proc.ess, ERTS_PROC_LOCK_MSGQ);
	    unlink_proc(btm);
	    erts_smp_proc_unlock(btm->receiver.proc.ess, ERTS_PROC_LOCK_MSGQ);
	}
	tab_remove(btm);
	ASSERT(!tab_find(BIF_ARG_1));
	erts_cancel_timer(&btm->tm);
	erts_smp_btm_rwunlock();
	res = erts_make_integer(left, BIF_P);
    }

    BIF_RET(res);
}

/* read_timer(Ref) -> false | RemainingTime */
BIF_RETTYPE read_timer_1(BIF_ALIST_1)
{
    Eterm res;
    ErtsBifTimer *btm;

    if (is_not_internal_ref(BIF_ARG_1)) {
	if (is_ref(BIF_ARG_1)) {
	    BIF_RET(am_false);
	}
	BIF_ERROR(BIF_P, BADARG);
    }

    if (erts_smp_safe_btm_rlock(BIF_P, ERTS_PROC_LOCK_MAIN))
	ERTS_BIF_EXITED(BIF_P);

    btm = tab_find(BIF_ARG_1);
    if (!btm || btm->flags & BTM_FLG_CANCELED) {
	res = am_false;
    }
    else {
	Uint left = erts_time_left(&btm->tm);
	res = erts_make_integer(left, BIF_P);
    }

    erts_smp_btm_runlock();

    BIF_RET(res);
}

void
erts_print_bif_timer_info(int to, void *to_arg)
{
    int i;
    int lock = !ERTS_IS_CRASH_DUMPING;

    if (lock)
	erts_smp_btm_rlock();

    for (i = 0; i < TIMER_HASH_VEC_SZ; i++) {
	ErtsBifTimer *btm;
	for (btm = bif_timer_tab[i]; btm; btm = btm->tab.next) {
	    Eterm receiver = (btm->flags & BTM_FLG_BYNAME
			      ? btm->receiver.name
			      : btm->receiver.proc.ess->id);
	    erts_print(to, to_arg, "=timer:%T\n", receiver);
	    erts_print(to, to_arg, "Message: %T\n", btm->message);
	    erts_print(to, to_arg, "Time left: %u ms\n",
		       erts_time_left(&btm->tm));
	}
    }

    if (lock)
	erts_smp_btm_runlock();
}


void
erts_cancel_bif_timers(Process *p, ErtsProcLocks plocks)
{
    ErtsBifTimer *btm;

    if (erts_smp_btm_tryrwlock() == EBUSY) {
	erts_smp_proc_unlock(p, plocks);
	erts_smp_btm_rwlock();
	erts_smp_proc_lock(p, plocks);
    }

    btm = p->u.bif_timers;
    while (btm) {
	ErtsBifTimer *tmp_btm;
	ASSERT(!(btm->flags & BTM_FLG_CANCELED));
	tab_remove(btm);
	tmp_btm = btm;
	btm = btm->receiver.proc.next;
	erts_cancel_timer(&tmp_btm->tm);
    }

    p->u.bif_timers = NULL;

    erts_smp_btm_rwunlock();
}

void erts_bif_timer_init(void)
{
    int i;
    no_bif_timers = 0;
    init_btm_pre_alloc();
    erts_smp_btm_lock_init();
    bif_timer_tab = erts_alloc(ERTS_ALC_T_BIF_TIMER_TABLE,
			       sizeof(ErtsBifTimer *)*TIMER_HASH_VEC_SZ);
    for (i = 0; i < TIMER_HASH_VEC_SZ; ++i)
	bif_timer_tab[i] = NULL;
}

Uint
erts_bif_timer_memory_size(void)
{
    Uint res;
    int lock = !ERTS_IS_CRASH_DUMPING;

    if (lock)
	erts_smp_btm_rlock();

    res = (sizeof(ErtsBifTimer *)*TIMER_HASH_VEC_SZ
	   + no_bif_timers*sizeof(ErtsBifTimer));

    if (lock)
	erts_smp_btm_runlock();

    return res;
}


void
erts_bif_timer_foreach(void (*func)(Eterm, Eterm, ErlHeapFragment *, void *),
		       void *arg)
{
    int i;

    ERTS_SMP_LC_ASSERT(erts_smp_thr_progress_is_blocking());

    for (i = 0; i < TIMER_HASH_VEC_SZ; i++) {
	ErtsBifTimer *btm;
	for (btm = bif_timer_tab[i]; btm; btm = btm->tab.next) {
	    (*func)((btm->flags & BTM_FLG_BYNAME
		     ? btm->receiver.name
		     : btm->receiver.proc.ess->id),
		    btm->message,
		    btm->bp,
		    arg);
	}
    }
}