2 Unix SMB/CIFS implementation.
3 main select loop and event handling
4 Copyright (C) Andrew Tridgell 2003
5 Copyright (C) Stefan Metzmacher 2009
7 ** NOTE! The following LGPL license applies to the tevent
8 ** library. This does NOT imply that all of Samba is released
11 This library is free software; you can redistribute it and/or
12 modify it under the terms of the GNU Lesser General Public
13 License as published by the Free Software Foundation; either
14 version 3 of the License, or (at your option) any later version.
16 This library is distributed in the hope that it will be useful,
17 but WITHOUT ANY WARRANTY; without even the implied warranty of
18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 Lesser General Public License for more details.
21 You should have received a copy of the GNU Lesser General Public
22 License along with this library; if not, see <http://www.gnu.org/licenses/>.
26 PLEASE READ THIS BEFORE MODIFYING!
28 This module is a general abstraction for the main select loop and
29 event handling. Do not ever put any localised hacks in here, instead
30 register one of the possible event types and implement that event
33 There are 2 types of event handling that are handled in this module:
35 1) a file descriptor becoming readable or writeable. This is mostly
36 used for network sockets, but can be used for any type of file
37 descriptor. You may only register one handler for each file
38 descriptor/io combination or you will get unpredictable results
39 (this means that you can have a handler for read events, and a
40 separate handler for write events, but not two handlers that are
41 both handling read events)
43 2) a timed event. You can register an event that happens at a
44 specific time. You can register as many of these as you
45 like. They are single shot - add a new timed event in the event
46 handler to get another event.
48 To setup a set of events you first need to create a event_context
49 structure using the function tevent_context_init(); This returns a
50 'struct tevent_context' that you use in all subsequent calls.
52 After that you can add/remove events that you are interested in
53 using tevent_add_*() and talloc_free()
55 Finally, you call tevent_loop_wait_once() to block waiting for one of the
56 events to occor or tevent_loop_wait() which will loop
61 #include "system/filesys.h"
63 #include "system/threads.h"
65 #define TEVENT_DEPRECATED 1
67 #include "tevent_internal.h"
68 #include "tevent_util.h"
70 #include <sys/eventfd.h>
73 static void tevent_abort(struct tevent_context *ev, const char *reason);
75 struct tevent_ops_list {
76 struct tevent_ops_list *next, *prev;
78 const struct tevent_ops *ops;
81 /* list of registered event backends */
82 static struct tevent_ops_list *tevent_backends = NULL;
83 static char *tevent_default_backend = NULL;
86 register an events backend
88 bool tevent_register_backend(const char *name, const struct tevent_ops *ops)
90 struct tevent_ops_list *e;
92 for (e = tevent_backends; e != NULL; e = e->next) {
93 if (0 == strcmp(e->name, name)) {
94 /* already registered, skip it */
99 e = talloc(NULL, struct tevent_ops_list);
100 if (e == NULL) return false;
104 DLIST_ADD(tevent_backends, e);
110 set the default event backend
112 void tevent_set_default_backend(const char *backend)
114 talloc_free(tevent_default_backend);
115 tevent_default_backend = talloc_strdup(NULL, backend);
119 initialise backends if not already done
121 static void tevent_backend_init(void)
131 tevent_select_init();
133 tevent_poll_mt_init();
134 #if defined(HAVE_EPOLL)
136 #elif defined(HAVE_SOLARIS_PORTS)
140 tevent_kqueue_init();
142 tevent_standard_init();
145 _PRIVATE_ const struct tevent_ops *tevent_find_ops_byname(const char *name)
147 struct tevent_ops_list *e;
149 tevent_backend_init();
152 name = tevent_default_backend;
158 for (e = tevent_backends; e != NULL; e = e->next) {
159 if (0 == strcmp(e->name, name)) {
168 list available backends
170 const char **tevent_backend_list(TALLOC_CTX *mem_ctx)
172 const char **list = NULL;
173 struct tevent_ops_list *e;
175 tevent_backend_init();
177 for (e=tevent_backends;e;e=e->next) {
178 list = ev_str_list_add(list, e->name);
181 talloc_steal(mem_ctx, list);
186 static void tevent_common_wakeup_fini(struct tevent_context *ev);
190 static pthread_mutex_t tevent_contexts_mutex = PTHREAD_MUTEX_INITIALIZER;
191 static struct tevent_context *tevent_contexts = NULL;
192 static pthread_once_t tevent_atfork_initialized = PTHREAD_ONCE_INIT;
194 static void tevent_atfork_prepare(void)
196 struct tevent_context *ev;
199 ret = pthread_mutex_lock(&tevent_contexts_mutex);
204 for (ev = tevent_contexts; ev != NULL; ev = ev->next) {
205 ret = pthread_mutex_lock(&ev->scheduled_mutex);
207 tevent_abort(ev, "pthread_mutex_lock failed");
212 static void tevent_atfork_parent(void)
214 struct tevent_context *ev;
217 for (ev = DLIST_TAIL(tevent_contexts); ev != NULL;
218 ev = DLIST_PREV(ev)) {
219 ret = pthread_mutex_unlock(&ev->scheduled_mutex);
221 tevent_abort(ev, "pthread_mutex_unlock failed");
225 ret = pthread_mutex_unlock(&tevent_contexts_mutex);
231 static void tevent_atfork_child(void)
233 struct tevent_context *ev;
236 for (ev = DLIST_TAIL(tevent_contexts); ev != NULL;
237 ev = DLIST_PREV(ev)) {
238 struct tevent_threaded_context *tctx;
240 for (tctx = ev->threaded_contexts; tctx != NULL;
242 tctx->event_ctx = NULL;
245 ev->threaded_contexts = NULL;
247 ret = pthread_mutex_unlock(&ev->scheduled_mutex);
249 tevent_abort(ev, "pthread_mutex_unlock failed");
253 ret = pthread_mutex_unlock(&tevent_contexts_mutex);
259 static void tevent_prep_atfork(void)
263 ret = pthread_atfork(tevent_atfork_prepare,
264 tevent_atfork_parent,
265 tevent_atfork_child);
273 int tevent_common_context_destructor(struct tevent_context *ev)
275 struct tevent_fd *fd, *fn;
276 struct tevent_timer *te, *tn;
277 struct tevent_immediate *ie, *in;
278 struct tevent_signal *se, *sn;
283 ret = pthread_mutex_lock(&tevent_contexts_mutex);
288 DLIST_REMOVE(tevent_contexts, ev);
290 ret = pthread_mutex_unlock(&tevent_contexts_mutex);
296 if (ev->threaded_contexts != NULL) {
298 * Threaded contexts are indicators that threads are
299 * about to send us immediates via
300 * tevent_threaded_schedule_immediate. The caller
301 * needs to make sure that the tevent context lives
302 * long enough to receive immediates from all threads.
304 tevent_abort(ev, "threaded contexts exist");
307 tevent_common_wakeup_fini(ev);
309 for (fd = ev->fd_events; fd; fd = fn) {
311 tevent_fd_set_flags(fd, 0);
312 fd->event_ctx = NULL;
313 DLIST_REMOVE(ev->fd_events, fd);
316 ev->last_zero_timer = NULL;
317 for (te = ev->timer_events; te; te = tn) {
319 te->event_ctx = NULL;
320 DLIST_REMOVE(ev->timer_events, te);
323 for (ie = ev->immediate_events; ie; ie = in) {
325 ie->event_ctx = NULL;
326 ie->cancel_fn = NULL;
327 DLIST_REMOVE(ev->immediate_events, ie);
330 for (se = ev->signal_events; se; se = sn) {
332 se->event_ctx = NULL;
333 DLIST_REMOVE(ev->signal_events, se);
335 * This is important, Otherwise signals
336 * are handled twice in child. eg, SIGHUP.
337 * one added in parent, and another one in
338 * the child. -- BoYang
340 tevent_cleanup_pending_signal_handlers(se);
343 /* removing nesting hook or we get an abort when nesting is
344 * not allowed. -- SSS
345 * Note that we need to leave the allowed flag at its current
346 * value, otherwise the use in tevent_re_initialise() will
347 * leave the event context with allowed forced to false, which
348 * will break users that expect nesting to be allowed
350 ev->nesting.level = 0;
351 ev->nesting.hook_fn = NULL;
352 ev->nesting.hook_private = NULL;
358 create a event_context structure for a specific implemementation.
359 This must be the first events call, and all subsequent calls pass
360 this event_context as the first element. Event handlers also
361 receive this as their first argument.
363 This function is for allowing third-party-applications to hook in gluecode
364 to their own event loop code, so that they can make async usage of our client libs
366 NOTE: use tevent_context_init() inside of samba!
368 struct tevent_context *tevent_context_init_ops(TALLOC_CTX *mem_ctx,
369 const struct tevent_ops *ops,
370 void *additional_data)
372 struct tevent_context *ev;
375 ev = talloc_zero(mem_ctx, struct tevent_context);
376 if (!ev) return NULL;
380 ret = pthread_once(&tevent_atfork_initialized, tevent_prep_atfork);
386 ret = pthread_mutex_init(&ev->scheduled_mutex, NULL);
392 ret = pthread_mutex_lock(&tevent_contexts_mutex);
394 pthread_mutex_destroy(&ev->scheduled_mutex);
399 DLIST_ADD(tevent_contexts, ev);
401 ret = pthread_mutex_unlock(&tevent_contexts_mutex);
408 talloc_set_destructor(ev, tevent_common_context_destructor);
411 ev->additional_data = additional_data;
413 ret = ev->ops->context_init(ev);
423 create a event_context structure. This must be the first events
424 call, and all subsequent calls pass this event_context as the first
425 element. Event handlers also receive this as their first argument.
427 struct tevent_context *tevent_context_init_byname(TALLOC_CTX *mem_ctx,
430 const struct tevent_ops *ops;
432 ops = tevent_find_ops_byname(name);
437 return tevent_context_init_ops(mem_ctx, ops, NULL);
442 create a event_context structure. This must be the first events
443 call, and all subsequent calls pass this event_context as the first
444 element. Event handlers also receive this as their first argument.
446 struct tevent_context *tevent_context_init(TALLOC_CTX *mem_ctx)
448 return tevent_context_init_byname(mem_ctx, NULL);
453 return NULL on failure (memory allocation error)
455 struct tevent_fd *_tevent_add_fd(struct tevent_context *ev,
459 tevent_fd_handler_t handler,
461 const char *handler_name,
462 const char *location)
464 return ev->ops->add_fd(ev, mem_ctx, fd, flags, handler, private_data,
465 handler_name, location);
469 set a close function on the fd event
471 void tevent_fd_set_close_fn(struct tevent_fd *fde,
472 tevent_fd_close_fn_t close_fn)
475 if (!fde->event_ctx) return;
476 fde->event_ctx->ops->set_fd_close_fn(fde, close_fn);
479 static void tevent_fd_auto_close_fn(struct tevent_context *ev,
480 struct tevent_fd *fde,
487 void tevent_fd_set_auto_close(struct tevent_fd *fde)
489 tevent_fd_set_close_fn(fde, tevent_fd_auto_close_fn);
493 return the fd event flags
495 uint16_t tevent_fd_get_flags(struct tevent_fd *fde)
498 if (!fde->event_ctx) return 0;
499 return fde->event_ctx->ops->get_fd_flags(fde);
503 set the fd event flags
505 void tevent_fd_set_flags(struct tevent_fd *fde, uint16_t flags)
508 if (!fde->event_ctx) return;
509 fde->event_ctx->ops->set_fd_flags(fde, flags);
512 bool tevent_signal_support(struct tevent_context *ev)
514 if (ev->ops->add_signal) {
520 static void (*tevent_abort_fn)(const char *reason);
522 void tevent_set_abort_fn(void (*abort_fn)(const char *reason))
524 tevent_abort_fn = abort_fn;
527 static void tevent_abort(struct tevent_context *ev, const char *reason)
529 tevent_debug(ev, TEVENT_DEBUG_FATAL,
530 "abort: %s\n", reason);
532 if (!tevent_abort_fn) {
536 tevent_abort_fn(reason);
541 return NULL on failure
543 struct tevent_timer *_tevent_add_timer(struct tevent_context *ev,
545 struct timeval next_event,
546 tevent_timer_handler_t handler,
548 const char *handler_name,
549 const char *location)
551 return ev->ops->add_timer(ev, mem_ctx, next_event, handler, private_data,
552 handler_name, location);
556 allocate an immediate event
557 return NULL on failure (memory allocation error)
559 struct tevent_immediate *_tevent_create_immediate(TALLOC_CTX *mem_ctx,
560 const char *location)
562 struct tevent_immediate *im;
564 im = talloc(mem_ctx, struct tevent_immediate);
565 if (im == NULL) return NULL;
569 im->event_ctx = NULL;
570 im->create_location = location;
572 im->private_data = NULL;
573 im->handler_name = NULL;
574 im->schedule_location = NULL;
575 im->cancel_fn = NULL;
576 im->additional_data = NULL;
582 schedule an immediate event
584 void _tevent_schedule_immediate(struct tevent_immediate *im,
585 struct tevent_context *ev,
586 tevent_immediate_handler_t handler,
588 const char *handler_name,
589 const char *location)
591 ev->ops->schedule_immediate(im, ev, handler, private_data,
592 handler_name, location);
598 sa_flags are flags to sigaction(2)
600 return NULL on failure
602 struct tevent_signal *_tevent_add_signal(struct tevent_context *ev,
606 tevent_signal_handler_t handler,
608 const char *handler_name,
609 const char *location)
611 return ev->ops->add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data,
612 handler_name, location);
615 void tevent_loop_allow_nesting(struct tevent_context *ev)
617 ev->nesting.allowed = true;
620 void tevent_loop_set_nesting_hook(struct tevent_context *ev,
621 tevent_nesting_hook hook,
624 if (ev->nesting.hook_fn &&
625 (ev->nesting.hook_fn != hook ||
626 ev->nesting.hook_private != private_data)) {
627 /* the way the nesting hook code is currently written
628 we cannot support two different nesting hooks at the
630 tevent_abort(ev, "tevent: Violation of nesting hook rules\n");
632 ev->nesting.hook_fn = hook;
633 ev->nesting.hook_private = private_data;
636 static void tevent_abort_nesting(struct tevent_context *ev, const char *location)
640 reason = talloc_asprintf(NULL, "tevent_loop_once() nesting at %s",
643 reason = "tevent_loop_once() nesting";
646 tevent_abort(ev, reason);
650 do a single event loop using the events defined in ev
652 int _tevent_loop_once(struct tevent_context *ev, const char *location)
655 void *nesting_stack_ptr = NULL;
659 if (ev->nesting.level > 1) {
660 if (!ev->nesting.allowed) {
661 tevent_abort_nesting(ev, location);
666 if (ev->nesting.level > 0) {
667 if (ev->nesting.hook_fn) {
669 ret2 = ev->nesting.hook_fn(ev,
670 ev->nesting.hook_private,
673 (void *)&nesting_stack_ptr,
682 tevent_trace_point_callback(ev, TEVENT_TRACE_BEFORE_LOOP_ONCE);
683 ret = ev->ops->loop_once(ev, location);
684 tevent_trace_point_callback(ev, TEVENT_TRACE_AFTER_LOOP_ONCE);
686 if (ev->nesting.level > 0) {
687 if (ev->nesting.hook_fn) {
689 ret2 = ev->nesting.hook_fn(ev,
690 ev->nesting.hook_private,
693 (void *)&nesting_stack_ptr,
708 this is a performance optimization for the samba4 nested event loop problems
710 int _tevent_loop_until(struct tevent_context *ev,
711 bool (*finished)(void *private_data),
713 const char *location)
716 void *nesting_stack_ptr = NULL;
720 if (ev->nesting.level > 1) {
721 if (!ev->nesting.allowed) {
722 tevent_abort_nesting(ev, location);
727 if (ev->nesting.level > 0) {
728 if (ev->nesting.hook_fn) {
730 ret2 = ev->nesting.hook_fn(ev,
731 ev->nesting.hook_private,
734 (void *)&nesting_stack_ptr,
743 while (!finished(private_data)) {
744 tevent_trace_point_callback(ev, TEVENT_TRACE_BEFORE_LOOP_ONCE);
745 ret = ev->ops->loop_once(ev, location);
746 tevent_trace_point_callback(ev, TEVENT_TRACE_AFTER_LOOP_ONCE);
752 if (ev->nesting.level > 0) {
753 if (ev->nesting.hook_fn) {
755 ret2 = ev->nesting.hook_fn(ev,
756 ev->nesting.hook_private,
759 (void *)&nesting_stack_ptr,
773 bool tevent_common_have_events(struct tevent_context *ev)
775 if (ev->fd_events != NULL) {
776 if (ev->fd_events != ev->wakeup_fde) {
779 if (ev->fd_events->next != NULL) {
784 * At this point we just have the wakeup pipe event as
785 * the only fd_event. That one does not count as a
786 * regular event, so look at the other event types.
790 return ((ev->timer_events != NULL) ||
791 (ev->immediate_events != NULL) ||
792 (ev->signal_events != NULL));
796 return on failure or (with 0) if all fd events are removed
798 int tevent_common_loop_wait(struct tevent_context *ev,
799 const char *location)
802 * loop as long as we have events pending
804 while (tevent_common_have_events(ev)) {
806 ret = _tevent_loop_once(ev, location);
808 tevent_debug(ev, TEVENT_DEBUG_FATAL,
809 "_tevent_loop_once() failed: %d - %s\n",
810 ret, strerror(errno));
815 tevent_debug(ev, TEVENT_DEBUG_WARNING,
816 "tevent_common_loop_wait() out of events\n");
821 return on failure or (with 0) if all fd events are removed
823 int _tevent_loop_wait(struct tevent_context *ev, const char *location)
825 return ev->ops->loop_wait(ev, location);
830 re-initialise a tevent context. This leaves you with the same
831 event context, but all events are wiped and the structure is
832 re-initialised. This is most useful after a fork()
834 zero is returned on success, non-zero on failure
836 int tevent_re_initialise(struct tevent_context *ev)
838 tevent_common_context_destructor(ev);
840 return ev->ops->context_init(ev);
843 static void wakeup_pipe_handler(struct tevent_context *ev,
844 struct tevent_fd *fde,
845 uint16_t flags, void *_private)
851 * This is the boilerplate for eventfd, but it works
852 * for pipes too. And as we don't care about the data
853 * we read, we're fine.
856 ret = read(fde->fd, &val, sizeof(val));
857 } while (ret == -1 && errno == EINTR);
861 * Initialize the wakeup pipe and pipe fde
864 int tevent_common_wakeup_init(struct tevent_context *ev)
868 if (ev->wakeup_fde != NULL) {
873 ret = eventfd(0, EFD_NONBLOCK);
881 ret = pipe(pipe_fds);
885 ev->wakeup_fd = pipe_fds[0];
886 ev->wakeup_write_fd = pipe_fds[1];
888 ev_set_blocking(ev->wakeup_fd, false);
889 ev_set_blocking(ev->wakeup_write_fd, false);
893 ev->wakeup_fde = tevent_add_fd(ev, ev, ev->wakeup_fd,
895 wakeup_pipe_handler, NULL);
896 if (ev->wakeup_fde == NULL) {
897 close(ev->wakeup_fd);
899 close(ev->wakeup_write_fd);
907 int tevent_common_wakeup(struct tevent_context *ev)
911 if (ev->wakeup_fde == NULL) {
918 ret = write(ev->wakeup_fd, &val, sizeof(val));
921 ret = write(ev->wakeup_write_fd, &c, 1);
923 } while ((ret == -1) && (errno == EINTR));
928 static void tevent_common_wakeup_fini(struct tevent_context *ev)
930 if (ev->wakeup_fde == NULL) {
934 TALLOC_FREE(ev->wakeup_fde);
936 close(ev->wakeup_fd);
938 close(ev->wakeup_write_fd);