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comparison src/os/unix/ngx_freebsd_rfork_thread.c @ 0:f0b350454894 NGINX_0_1_0

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nginx 0.1.0 *) The first public version.
author Igor Sysoev <http://sysoev.ru>
date Mon, 04 Oct 2004 00:00:00 +0400
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children 46833bd150cb
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-1:000000000000 0:f0b350454894
1
2 /*
3 * Copyright (C) Igor Sysoev
4 */
5
6
7 #include <ngx_config.h>
8 #include <ngx_core.h>
9
10 /*
11 * The threads implementation uses the rfork(RFPROC|RFTHREAD|RFMEM) syscall
12 * to create threads. All threads use the stacks of the same size mmap()ed
13 * below the main stack. Thus the current thread id is determinated via
14 * the stack pointer value.
15 *
16 * The mutex implementation uses the ngx_atomic_cmp_set() operation
17 * to acquire a mutex and the SysV semaphore to wait on a mutex and to wake up
18 * the waiting threads. The light mutex does not use semaphore, so after
19 * spinning in the lock the thread calls sched_yield(). However the light
20 * mutecies are intended to be used with the "trylock" operation only.
21 * The SysV semop() is a cheap syscall, particularly if it has little sembuf's
22 * and does not use SEM_UNDO.
23 *
24 * The condition variable implementation uses signal #64. The signal handler
25 * is SIG_IGN so the kill() is a cheap syscall. The thread waits a signal
26 * in kevent(). The use of the EVFILT_SIGNAL is safe since FreeBSD 4.7.
27 *
28 * This threads implementation currently works on i386 (486+) and amd64
29 * platforms only.
30 */
31
32
33 char *ngx_freebsd_kern_usrstack;
34 size_t ngx_thread_stack_size;
35
36
37 static size_t rz_size;
38 static size_t usable_stack_size;
39 static char *last_stack;
40
41 static ngx_uint_t nthreads;
42 static ngx_uint_t max_threads;
43
44 static ngx_uint_t nkeys;
45 static ngx_tid_t *tids; /* the threads tids array */
46 void **ngx_tls; /* the threads tls's array */
47
48 /* the thread-safe libc errno */
49
50 static int errno0; /* the main thread's errno */
51 static int *errnos; /* the threads errno's array */
52
53 int *__error()
54 {
55 int tid;
56
57 tid = ngx_gettid();
58
59 return tid ? &errnos[tid - 1] : &errno0;
60 }
61
62
63 /*
64 * __isthreaded enables the spinlocks in some libc functions, i.e. in malloc()
65 * and some other places. Nevertheless we protect our malloc()/free() calls
66 * by own mutex that is more efficient than the spinlock.
67 *
68 * _spinlock() is a weak referenced stub in src/lib/libc/gen/_spinlock_stub.c
69 * that does nothing.
70 */
71
72 extern int __isthreaded;
73
74 void _spinlock(ngx_atomic_t *lock)
75 {
76 ngx_int_t tries;
77
78 tries = 0;
79
80 for ( ;; ) {
81
82 if (*lock) {
83 if (ngx_ncpu > 1 && tries++ < 1000) {
84 continue;
85 }
86
87 sched_yield();
88 tries = 0;
89
90 } else {
91 if (ngx_atomic_cmp_set(lock, 0, 1)) {
92 return;
93 }
94 }
95 }
96 }
97
98
99 /*
100 * Before FreeBSD 5.1 _spinunlock() is a simple #define in
101 * src/lib/libc/include/spinlock.h that zeroes lock.
102 *
103 * Since FreeBSD 5.1 _spinunlock() is a weak referenced stub in
104 * src/lib/libc/gen/_spinlock_stub.c that does nothing.
105 */
106
107 #ifndef _spinunlock
108
109 void _spinunlock(ngx_atomic_t *lock)
110 {
111 *lock = 0;
112 }
113
114 #endif
115
116
117 int ngx_create_thread(ngx_tid_t *tid, void* (*func)(void *arg), void *arg,
118 ngx_log_t *log)
119 {
120 int id, err;
121 char *stack, *stack_top;
122
123 if (nthreads >= max_threads) {
124 ngx_log_error(NGX_LOG_CRIT, log, 0,
125 "no more than %d threads can be created", max_threads);
126 return NGX_ERROR;
127 }
128
129 last_stack -= ngx_thread_stack_size;
130
131 stack = mmap(last_stack, usable_stack_size, PROT_READ|PROT_WRITE,
132 MAP_STACK, -1, 0);
133
134 if (stack == MAP_FAILED) {
135 ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
136 "mmap(" PTR_FMT ":" SIZE_T_FMT
137 ", MAP_STACK) thread stack failed",
138 last_stack, usable_stack_size);
139 return NGX_ERROR;
140 }
141
142 if (stack != last_stack) {
143 ngx_log_error(NGX_LOG_ALERT, log, 0, "stack address was changed");
144 }
145
146 stack_top = stack + usable_stack_size;
147
148 ngx_log_debug2(NGX_LOG_DEBUG_CORE, log, 0,
149 "thread stack: " PTR_FMT "-" PTR_FMT, stack, stack_top);
150
151 ngx_set_errno(0);
152
153 id = rfork_thread(RFPROC|RFTHREAD|RFMEM, stack_top,
154 (ngx_rfork_thread_func_pt) func, arg);
155
156 err = ngx_errno;
157
158 if (id == -1) {
159 ngx_log_error(NGX_LOG_ALERT, log, err, "rfork() failed");
160
161 } else {
162 *tid = id;
163 nthreads = (ngx_freebsd_kern_usrstack - stack_top)
164 / ngx_thread_stack_size;
165 tids[nthreads] = id;
166
167 ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0, "rfork()ed thread: %d", id);
168 }
169
170 return err;
171 }
172
173
174 ngx_int_t ngx_init_threads(int n, size_t size, ngx_cycle_t *cycle)
175 {
176 char *red_zone, *zone;
177 size_t len;
178 ngx_int_t i;
179 struct sigaction sa;
180
181 max_threads = n + 1;
182
183 for (i = 0; i < n; i++) {
184 ngx_memzero(&sa, sizeof(struct sigaction));
185 sa.sa_handler = SIG_IGN;
186 sigemptyset(&sa.sa_mask);
187 if (sigaction(NGX_CV_SIGNAL, &sa, NULL) == -1) {
188 ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
189 "sigaction(%d, SIG_IGN) failed", NGX_CV_SIGNAL);
190 return NGX_ERROR;
191 }
192 }
193
194 len = sizeof(ngx_freebsd_kern_usrstack);
195 if (sysctlbyname("kern.usrstack", &ngx_freebsd_kern_usrstack, &len,
196 NULL, 0) == -1)
197 {
198 ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
199 "sysctlbyname(kern.usrstack) failed");
200 return NGX_ERROR;
201 }
202
203 /* the main thread stack red zone */
204 rz_size = ngx_pagesize;
205 red_zone = ngx_freebsd_kern_usrstack - (size + rz_size);
206
207 ngx_log_debug2(NGX_LOG_DEBUG_CORE, cycle->log, 0,
208 "usrstack: " PTR_FMT " red zone: " PTR_FMT,
209 ngx_freebsd_kern_usrstack, red_zone);
210
211 zone = mmap(red_zone, rz_size, PROT_NONE, MAP_ANON, -1, 0);
212 if (zone == MAP_FAILED) {
213 ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
214 "mmap(" PTR_FMT ":" SIZE_T_FMT
215 ", PROT_NONE, MAP_ANON) red zone failed",
216 red_zone, rz_size);
217 return NGX_ERROR;
218 }
219
220 if (zone != red_zone) {
221 ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
222 "red zone address was changed");
223 }
224
225 /* create the threads errno's array */
226
227 if (!(errnos = ngx_calloc(n * sizeof(int), cycle->log))) {
228 return NGX_ERROR;
229 }
230
231 /* create the threads tids array */
232
233 if (!(tids = ngx_calloc((n + 1) * sizeof(ngx_tid_t), cycle->log))) {
234 return NGX_ERROR;
235 }
236
237 tids[0] = ngx_pid;
238
239 /* create the threads tls's array */
240
241 ngx_tls = ngx_calloc(NGX_THREAD_KEYS_MAX * (n + 1) * sizeof(void *),
242 cycle->log);
243 if (ngx_tls == NULL) {
244 return NGX_ERROR;
245 }
246
247 nthreads = 1;
248
249 last_stack = zone + rz_size;
250 usable_stack_size = size;
251 ngx_thread_stack_size = size + rz_size;
252
253 /* allow the spinlock in libc malloc() */
254 __isthreaded = 1;
255
256 ngx_threaded = 1;
257
258 return NGX_OK;
259 }
260
261
262 ngx_tid_t ngx_thread_self()
263 {
264 int tid;
265 ngx_tid_t pid;
266
267 tid = ngx_gettid();
268
269 if (tids == NULL) {
270 return ngx_pid;
271 }
272
273 return tids[tid];
274 }
275
276
277 ngx_int_t ngx_thread_key_create(ngx_tls_key_t *key)
278 {
279 if (nkeys >= NGX_THREAD_KEYS_MAX) {
280 return NGX_ENOMEM;
281 }
282
283 *key = nkeys++;
284
285 return 0;
286 }
287
288
289 ngx_int_t ngx_thread_set_tls(ngx_tls_key_t key, void *value)
290 {
291 if (key >= NGX_THREAD_KEYS_MAX) {
292 return NGX_EINVAL;
293 }
294
295 ngx_tls[key * NGX_THREAD_KEYS_MAX + ngx_gettid()] = value;
296 return 0;
297 }
298
299
300 ngx_mutex_t *ngx_mutex_init(ngx_log_t *log, uint flags)
301 {
302 ngx_mutex_t *m;
303 union semun op;
304
305 if (!(m = ngx_alloc(sizeof(ngx_mutex_t), log))) {
306 return NULL;
307 }
308
309 m->lock = 0;
310 m->log = log;
311
312 if (flags & NGX_MUTEX_LIGHT) {
313 m->semid = -1;
314 return m;
315 }
316
317 m->semid = semget(IPC_PRIVATE, 1, SEM_R|SEM_A);
318 if (m->semid == -1) {
319 ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "semget() failed");
320 return NULL;
321 }
322
323 op.val = 0;
324
325 if (semctl(m->semid, 0, SETVAL, op) == -1) {
326 ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "semctl(SETVAL) failed");
327
328 if (semctl(m->semid, 0, IPC_RMID) == -1) {
329 ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
330 "semctl(IPC_RMID) failed");
331 }
332
333 return NULL;
334 }
335
336 return m;
337 }
338
339
340 void ngx_mutex_destroy(ngx_mutex_t *m)
341 {
342 if (semctl(m->semid, 0, IPC_RMID) == -1) {
343 ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
344 "semctl(IPC_RMID) failed");
345 }
346
347 ngx_free((void *) m);
348 }
349
350
351 ngx_int_t ngx_mutex_dolock(ngx_mutex_t *m, ngx_int_t try)
352 {
353 uint32_t lock, new, old;
354 ngx_uint_t tries;
355 struct sembuf op;
356
357 if (!ngx_threaded) {
358 return NGX_OK;
359 }
360
361 #if (NGX_DEBUG)
362 if (try) {
363 ngx_log_debug2(NGX_LOG_DEBUG_MUTEX, m->log, 0,
364 "try lock mutex " PTR_FMT " lock:%X", m, m->lock);
365 } else {
366 ngx_log_debug2(NGX_LOG_DEBUG_MUTEX, m->log, 0,
367 "lock mutex " PTR_FMT " lock:%X", m, m->lock);
368 }
369 #endif
370
371 old = m->lock;
372 tries = 0;
373
374 for ( ;; ) {
375 if (old & NGX_MUTEX_LOCK_BUSY) {
376
377 if (try) {
378 return NGX_AGAIN;
379 }
380
381 if (ngx_freebsd_hw_ncpu > 1 && tries++ < 1000) {
382
383 /* the spinlock is used only on the SMP system */
384
385 old = m->lock;
386 continue;
387 }
388
389 if (m->semid == -1) {
390 sched_yield();
391
392 tries = 0;
393 old = m->lock;
394 continue;
395 }
396
397 ngx_log_debug2(NGX_LOG_DEBUG_MUTEX, m->log, 0,
398 "mutex " PTR_FMT " lock:%X", m, m->lock);
399
400 /*
401 * The mutex is locked so we increase a number
402 * of the threads that are waiting on the mutex
403 */
404
405 lock = old + 1;
406
407 if ((lock & ~NGX_MUTEX_LOCK_BUSY) > nthreads) {
408 ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
409 "%d threads wait for mutex " PTR_FMT
410 ", while only %d threads are available",
411 lock & ~NGX_MUTEX_LOCK_BUSY, m, nthreads);
412 return NGX_ERROR;
413 }
414
415 if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
416
417 ngx_log_debug2(NGX_LOG_DEBUG_MUTEX, m->log, 0,
418 "wait mutex " PTR_FMT " lock:%X", m, m->lock);
419
420 /*
421 * The number of the waiting threads has been increased
422 * and we would wait on the SysV semaphore.
423 * A semaphore should wake up us more efficiently than
424 * a simple sched_yield() or usleep().
425 */
426
427 op.sem_num = 0;
428 op.sem_op = -1;
429 op.sem_flg = 0;
430
431 if (semop(m->semid, &op, 1) == -1) {
432 ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
433 "semop() failed while waiting "
434 "on mutex " PTR_FMT, m);
435 return NGX_ERROR;
436 }
437
438 ngx_log_debug2(NGX_LOG_DEBUG_MUTEX, m->log, 0,
439 "mutex waked up " PTR_FMT " lock:%X",
440 m, m->lock);
441
442 tries = 0;
443 old = m->lock;
444 continue;
445 }
446
447 old = m->lock;
448
449 } else {
450 lock = old | NGX_MUTEX_LOCK_BUSY;
451
452 if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
453
454 /* we locked the mutex */
455
456 break;
457 }
458
459 old = m->lock;
460 }
461
462 if (tries++ > 1000) {
463
464 ngx_log_debug1(NGX_LOG_DEBUG_MUTEX, m->log, 0,
465 "mutex " PTR_FMT " is contested", m);
466
467 /* the mutex is probably contested so we are giving up now */
468
469 sched_yield();
470
471 tries = 0;
472 old = m->lock;
473 }
474 }
475
476 ngx_log_debug2(NGX_LOG_DEBUG_MUTEX, m->log, 0,
477 "mutex " PTR_FMT " is locked, lock:%X", m, m->lock);
478
479 return NGX_OK;
480 }
481
482
483 ngx_int_t ngx_mutex_unlock(ngx_mutex_t *m)
484 {
485 uint32_t lock, new, old;
486 struct sembuf op;
487
488 if (!ngx_threaded) {
489 return NGX_OK;
490 }
491
492 old = m->lock;
493
494 if (!(old & NGX_MUTEX_LOCK_BUSY)) {
495 ngx_log_error(NGX_LOG_ALERT, m->log, 0,
496 "trying to unlock the free mutex " PTR_FMT, m);
497 return NGX_ERROR;
498 }
499
500 /* free the mutex */
501
502 #if 0
503 ngx_log_debug2(NGX_LOG_DEBUG_MUTEX, m->log, 0,
504 "unlock mutex " PTR_FMT " lock:%X", m, old);
505 #endif
506
507 for ( ;; ) {
508 lock = old & ~NGX_MUTEX_LOCK_BUSY;
509
510 if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
511 break;
512 }
513
514 old = m->lock;
515 }
516
517 if (m->semid == -1) {
518 ngx_log_debug1(NGX_LOG_DEBUG_MUTEX, m->log, 0,
519 "mutex " PTR_FMT " is unlocked", m);
520
521 return NGX_OK;
522 }
523
524 /* check whether we need to wake up a waiting thread */
525
526 old = m->lock;
527
528 for ( ;; ) {
529 if (old & NGX_MUTEX_LOCK_BUSY) {
530
531 /* the mutex is just locked by another thread */
532
533 break;
534 }
535
536 if (old == 0) {
537 break;
538 }
539
540 /* there are the waiting threads */
541
542 lock = old - 1;
543
544 if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
545
546 /* wake up the thread that waits on semaphore */
547
548 ngx_log_debug1(NGX_LOG_DEBUG_MUTEX, m->log, 0,
549 "wake up mutex " PTR_FMT "", m);
550
551 op.sem_num = 0;
552 op.sem_op = 1;
553 op.sem_flg = 0;
554
555 if (semop(m->semid, &op, 1) == -1) {
556 ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
557 "semop() failed while waking up on mutex "
558 PTR_FMT, m);
559 return NGX_ERROR;
560 }
561
562 break;
563 }
564
565 old = m->lock;
566 }
567
568 ngx_log_debug1(NGX_LOG_DEBUG_MUTEX, m->log, 0,
569 "mutex " PTR_FMT " is unlocked", m);
570
571 return NGX_OK;
572 }
573
574
575 ngx_cond_t *ngx_cond_init(ngx_log_t *log)
576 {
577 ngx_cond_t *cv;
578
579 if (!(cv = ngx_alloc(sizeof(ngx_cond_t), log))) {
580 return NULL;
581 }
582
583 cv->signo = NGX_CV_SIGNAL;
584 cv->tid = 0;
585 cv->log = log;
586 cv->kq = -1;
587
588 return cv;
589 }
590
591
592 void ngx_cond_destroy(ngx_cond_t *cv)
593 {
594 if (close(cv->kq) == -1) {
595 ngx_log_error(NGX_LOG_ALERT, cv->log, ngx_errno,
596 "kqueue close() failed");
597 }
598
599 ngx_free(cv);
600 }
601
602
603 ngx_int_t ngx_cond_wait(ngx_cond_t *cv, ngx_mutex_t *m)
604 {
605 int n;
606 ngx_err_t err;
607 struct kevent kev;
608 struct timespec ts;
609
610 if (cv->kq == -1) {
611
612 /*
613 * We have to add the EVFILT_SIGNAL filter in the rfork()ed thread.
614 * Otherwise the thread would not get a signal event.
615 *
616 * However, we have not to open the kqueue in the thread,
617 * it is simply handy do it together.
618 */
619
620 cv->kq = kqueue();
621 if (cv->kq == -1) {
622 ngx_log_error(NGX_LOG_ALERT, cv->log, ngx_errno, "kqueue() failed");
623 return NGX_ERROR;
624 }
625
626 ngx_log_debug2(NGX_LOG_DEBUG_CORE, cv->log, 0,
627 "cv kq:%d signo:%d", cv->kq, cv->signo);
628
629 kev.ident = cv->signo;
630 kev.filter = EVFILT_SIGNAL;
631 kev.flags = EV_ADD;
632 kev.fflags = 0;
633 kev.data = 0;
634 kev.udata = NULL;
635
636 ts.tv_sec = 0;
637 ts.tv_nsec = 0;
638
639 if (kevent(cv->kq, &kev, 1, NULL, 0, &ts) == -1) {
640 ngx_log_error(NGX_LOG_ALERT, cv->log, ngx_errno, "kevent() failed");
641 return NGX_ERROR;
642 }
643 }
644
645 if (ngx_mutex_unlock(m) == NGX_ERROR) {
646 return NGX_ERROR;
647 }
648
649 ngx_log_debug3(NGX_LOG_DEBUG_CORE, cv->log, 0,
650 "cv " PTR_FMT " wait, kq:%d, signo:%d",
651 cv, cv->kq, cv->signo);
652
653 for ( ;; ) {
654 n = kevent(cv->kq, NULL, 0, &kev, 1, NULL);
655
656 ngx_log_debug2(NGX_LOG_DEBUG_CORE, cv->log, 0,
657 "cv " PTR_FMT " kevent: %d", cv, n);
658
659 if (n == -1) {
660 err = ngx_errno;
661 ngx_log_error((err == NGX_EINTR) ? NGX_LOG_INFO : NGX_LOG_ALERT,
662 cv->log, ngx_errno,
663 "kevent() failed while waiting condition variable "
664 PTR_FMT, cv);
665
666 if (err == NGX_EINTR) {
667 break;
668 }
669
670 return NGX_ERROR;
671 }
672
673 if (n == 0) {
674 ngx_log_error(NGX_LOG_ALERT, cv->log, 0,
675 "kevent() returned no events "
676 "while waiting condition variable " PTR_FMT,
677 cv);
678 continue;
679 }
680
681 if (kev.filter != EVFILT_SIGNAL) {
682 ngx_log_error(NGX_LOG_ALERT, cv->log, 0,
683 "kevent() returned unexpected events: %d "
684 "while waiting condition variable " PTR_FMT,
685 kev.filter, cv);
686 continue;
687 }
688
689 if (kev.ident != (uintptr_t) cv->signo) {
690 ngx_log_error(NGX_LOG_ALERT, cv->log, 0,
691 "kevent() returned unexpected signal: %d ",
692 "while waiting condition variable " PTR_FMT,
693 kev.ident, cv);
694 continue;
695 }
696
697 break;
698 }
699
700 ngx_log_debug1(NGX_LOG_DEBUG_CORE, cv->log, 0,
701 "cv " PTR_FMT " is waked up", cv);
702
703 if (ngx_mutex_lock(m) == NGX_ERROR) {
704 return NGX_ERROR;
705 }
706
707 return NGX_OK;
708 }
709
710
711 ngx_int_t ngx_cond_signal(ngx_cond_t *cv)
712 {
713 ngx_err_t err;
714
715 ngx_log_debug3(NGX_LOG_DEBUG_CORE, cv->log, 0,
716 "cv " PTR_FMT " to signal " PID_T_FMT " %d",
717 cv, cv->tid, cv->signo);
718
719 if (kill(cv->tid, cv->signo) == -1) {
720
721 err = ngx_errno;
722
723 ngx_log_error(NGX_LOG_ALERT, cv->log, err,
724 "kill() failed while signaling condition variable "
725 PTR_FMT, cv);
726
727 if (err == NGX_ESRCH) {
728 cv->tid = -1;
729 }
730
731 return NGX_ERROR;
732 }
733
734 ngx_log_debug1(NGX_LOG_DEBUG_CORE, cv->log, 0,
735 "cv " PTR_FMT " is signaled", cv);
736
737 return NGX_OK;
738 }