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"
62 #define TEVENT_DEPRECATED 1
64 #include "tevent_internal.h"
65 #include "tevent_util.h"
67 struct tevent_ops_list {
68 struct tevent_ops_list *next, *prev;
70 const struct tevent_ops *ops;
73 /* list of registered event backends */
74 static struct tevent_ops_list *tevent_backends = NULL;
75 static char *tevent_default_backend = NULL;
78 register an events backend
80 bool tevent_register_backend(const char *name, const struct tevent_ops *ops)
82 struct tevent_ops_list *e;
84 for (e = tevent_backends; e != NULL; e = e->next) {
85 if (0 == strcmp(e->name, name)) {
86 /* already registered, skip it */
91 e = talloc(NULL, struct tevent_ops_list);
92 if (e == NULL) return false;
96 DLIST_ADD(tevent_backends, e);
102 set the default event backend
104 void tevent_set_default_backend(const char *backend)
106 talloc_free(tevent_default_backend);
107 tevent_default_backend = talloc_strdup(NULL, backend);
111 initialise backends if not already done
113 static void tevent_backend_init(void)
115 tevent_select_init();
117 tevent_poll_mt_init();
121 tevent_standard_init();
124 _PRIVATE_ const struct tevent_ops *tevent_find_ops_byname(const char *name)
126 struct tevent_ops_list *e;
128 tevent_backend_init();
131 name = tevent_default_backend;
137 for (e = tevent_backends; e != NULL; e = e->next) {
138 if (0 == strcmp(e->name, name)) {
147 list available backends
149 const char **tevent_backend_list(TALLOC_CTX *mem_ctx)
151 const char **list = NULL;
152 struct tevent_ops_list *e;
154 tevent_backend_init();
156 for (e=tevent_backends;e;e=e->next) {
157 list = ev_str_list_add(list, e->name);
160 talloc_steal(mem_ctx, list);
165 int tevent_common_context_destructor(struct tevent_context *ev)
167 struct tevent_fd *fd, *fn;
168 struct tevent_timer *te, *tn;
169 struct tevent_immediate *ie, *in;
170 struct tevent_signal *se, *sn;
173 talloc_free(ev->pipe_fde);
174 close(ev->pipe_fds[0]);
175 close(ev->pipe_fds[1]);
179 for (fd = ev->fd_events; fd; fd = fn) {
181 fd->event_ctx = NULL;
182 DLIST_REMOVE(ev->fd_events, fd);
185 for (te = ev->timer_events; te; te = tn) {
187 te->event_ctx = NULL;
188 DLIST_REMOVE(ev->timer_events, te);
191 for (ie = ev->immediate_events; ie; ie = in) {
193 ie->event_ctx = NULL;
194 ie->cancel_fn = NULL;
195 DLIST_REMOVE(ev->immediate_events, ie);
198 for (se = ev->signal_events; se; se = sn) {
200 se->event_ctx = NULL;
201 DLIST_REMOVE(ev->signal_events, se);
203 * This is important, Otherwise signals
204 * are handled twice in child. eg, SIGHUP.
205 * one added in parent, and another one in
206 * the child. -- BoYang
208 tevent_cleanup_pending_signal_handlers(se);
211 /* removing nesting hook or we get an abort when nesting is
212 * not allowed. -- SSS
213 * Note that we need to leave the allowed flag at its current
214 * value, otherwise the use in tevent_re_initialise() will
215 * leave the event context with allowed forced to false, which
216 * will break users that expect nesting to be allowed
218 ev->nesting.level = 0;
219 ev->nesting.hook_fn = NULL;
220 ev->nesting.hook_private = NULL;
226 create a event_context structure for a specific implemementation.
227 This must be the first events call, and all subsequent calls pass
228 this event_context as the first element. Event handlers also
229 receive this as their first argument.
231 This function is for allowing third-party-applications to hook in gluecode
232 to their own event loop code, so that they can make async usage of our client libs
234 NOTE: use tevent_context_init() inside of samba!
236 struct tevent_context *tevent_context_init_ops(TALLOC_CTX *mem_ctx,
237 const struct tevent_ops *ops,
238 void *additional_data)
240 struct tevent_context *ev;
243 ev = talloc_zero(mem_ctx, struct tevent_context);
244 if (!ev) return NULL;
246 talloc_set_destructor(ev, tevent_common_context_destructor);
249 ev->additional_data = additional_data;
251 ret = ev->ops->context_init(ev);
261 create a event_context structure. This must be the first events
262 call, and all subsequent calls pass this event_context as the first
263 element. Event handlers also receive this as their first argument.
265 struct tevent_context *tevent_context_init_byname(TALLOC_CTX *mem_ctx,
268 struct tevent_ops_list *e;
270 tevent_backend_init();
273 name = tevent_default_backend;
279 for (e=tevent_backends;e;e=e->next) {
280 if (strcmp(name, e->name) == 0) {
281 return tevent_context_init_ops(mem_ctx, e->ops, NULL);
289 create a event_context structure. This must be the first events
290 call, and all subsequent calls pass this event_context as the first
291 element. Event handlers also receive this as their first argument.
293 struct tevent_context *tevent_context_init(TALLOC_CTX *mem_ctx)
295 return tevent_context_init_byname(mem_ctx, NULL);
300 return NULL on failure (memory allocation error)
302 struct tevent_fd *_tevent_add_fd(struct tevent_context *ev,
306 tevent_fd_handler_t handler,
308 const char *handler_name,
309 const char *location)
311 return ev->ops->add_fd(ev, mem_ctx, fd, flags, handler, private_data,
312 handler_name, location);
316 set a close function on the fd event
318 void tevent_fd_set_close_fn(struct tevent_fd *fde,
319 tevent_fd_close_fn_t close_fn)
322 if (!fde->event_ctx) return;
323 fde->event_ctx->ops->set_fd_close_fn(fde, close_fn);
326 static void tevent_fd_auto_close_fn(struct tevent_context *ev,
327 struct tevent_fd *fde,
334 void tevent_fd_set_auto_close(struct tevent_fd *fde)
336 tevent_fd_set_close_fn(fde, tevent_fd_auto_close_fn);
340 return the fd event flags
342 uint16_t tevent_fd_get_flags(struct tevent_fd *fde)
345 if (!fde->event_ctx) return 0;
346 return fde->event_ctx->ops->get_fd_flags(fde);
350 set the fd event flags
352 void tevent_fd_set_flags(struct tevent_fd *fde, uint16_t flags)
355 if (!fde->event_ctx) return;
356 fde->event_ctx->ops->set_fd_flags(fde, flags);
359 bool tevent_signal_support(struct tevent_context *ev)
361 if (ev->ops->add_signal) {
367 static void (*tevent_abort_fn)(const char *reason);
369 void tevent_set_abort_fn(void (*abort_fn)(const char *reason))
371 tevent_abort_fn = abort_fn;
374 static void tevent_abort(struct tevent_context *ev, const char *reason)
376 tevent_debug(ev, TEVENT_DEBUG_FATAL,
377 "abort: %s\n", reason);
379 if (!tevent_abort_fn) {
383 tevent_abort_fn(reason);
388 return NULL on failure
390 struct tevent_timer *_tevent_add_timer(struct tevent_context *ev,
392 struct timeval next_event,
393 tevent_timer_handler_t handler,
395 const char *handler_name,
396 const char *location)
398 return ev->ops->add_timer(ev, mem_ctx, next_event, handler, private_data,
399 handler_name, location);
403 allocate an immediate event
404 return NULL on failure (memory allocation error)
406 struct tevent_immediate *_tevent_create_immediate(TALLOC_CTX *mem_ctx,
407 const char *location)
409 struct tevent_immediate *im;
411 im = talloc(mem_ctx, struct tevent_immediate);
412 if (im == NULL) return NULL;
416 im->event_ctx = NULL;
417 im->create_location = location;
419 im->private_data = NULL;
420 im->handler_name = NULL;
421 im->schedule_location = NULL;
422 im->cancel_fn = NULL;
423 im->additional_data = NULL;
429 schedule an immediate event
431 void _tevent_schedule_immediate(struct tevent_immediate *im,
432 struct tevent_context *ev,
433 tevent_immediate_handler_t handler,
435 const char *handler_name,
436 const char *location)
438 ev->ops->schedule_immediate(im, ev, handler, private_data,
439 handler_name, location);
445 sa_flags are flags to sigaction(2)
447 return NULL on failure
449 struct tevent_signal *_tevent_add_signal(struct tevent_context *ev,
453 tevent_signal_handler_t handler,
455 const char *handler_name,
456 const char *location)
458 return ev->ops->add_signal(ev, mem_ctx, signum, sa_flags, handler, private_data,
459 handler_name, location);
462 void tevent_loop_allow_nesting(struct tevent_context *ev)
464 ev->nesting.allowed = true;
467 void tevent_loop_set_nesting_hook(struct tevent_context *ev,
468 tevent_nesting_hook hook,
471 if (ev->nesting.hook_fn &&
472 (ev->nesting.hook_fn != hook ||
473 ev->nesting.hook_private != private_data)) {
474 /* the way the nesting hook code is currently written
475 we cannot support two different nesting hooks at the
477 tevent_abort(ev, "tevent: Violation of nesting hook rules\n");
479 ev->nesting.hook_fn = hook;
480 ev->nesting.hook_private = private_data;
483 static void tevent_abort_nesting(struct tevent_context *ev, const char *location)
487 reason = talloc_asprintf(NULL, "tevent_loop_once() nesting at %s",
490 reason = "tevent_loop_once() nesting";
493 tevent_abort(ev, reason);
497 do a single event loop using the events defined in ev
499 int _tevent_loop_once(struct tevent_context *ev, const char *location)
502 void *nesting_stack_ptr = NULL;
506 if (ev->nesting.level > 1) {
507 if (!ev->nesting.allowed) {
508 tevent_abort_nesting(ev, location);
513 if (ev->nesting.level > 0) {
514 if (ev->nesting.hook_fn) {
516 ret2 = ev->nesting.hook_fn(ev,
517 ev->nesting.hook_private,
520 (void *)&nesting_stack_ptr,
529 ret = ev->ops->loop_once(ev, location);
531 if (ev->nesting.level > 0) {
532 if (ev->nesting.hook_fn) {
534 ret2 = ev->nesting.hook_fn(ev,
535 ev->nesting.hook_private,
538 (void *)&nesting_stack_ptr,
553 this is a performance optimization for the samba4 nested event loop problems
555 int _tevent_loop_until(struct tevent_context *ev,
556 bool (*finished)(void *private_data),
558 const char *location)
561 void *nesting_stack_ptr = NULL;
565 if (ev->nesting.level > 1) {
566 if (!ev->nesting.allowed) {
567 tevent_abort_nesting(ev, location);
572 if (ev->nesting.level > 0) {
573 if (ev->nesting.hook_fn) {
575 ret2 = ev->nesting.hook_fn(ev,
576 ev->nesting.hook_private,
579 (void *)&nesting_stack_ptr,
588 while (!finished(private_data)) {
589 ret = ev->ops->loop_once(ev, location);
595 if (ev->nesting.level > 0) {
596 if (ev->nesting.hook_fn) {
598 ret2 = ev->nesting.hook_fn(ev,
599 ev->nesting.hook_private,
602 (void *)&nesting_stack_ptr,
617 return on failure or (with 0) if all fd events are removed
619 int tevent_common_loop_wait(struct tevent_context *ev,
620 const char *location)
623 * loop as long as we have events pending
625 while (ev->fd_events ||
627 ev->immediate_events ||
630 ret = _tevent_loop_once(ev, location);
632 tevent_debug(ev, TEVENT_DEBUG_FATAL,
633 "_tevent_loop_once() failed: %d - %s\n",
634 ret, strerror(errno));
639 tevent_debug(ev, TEVENT_DEBUG_WARNING,
640 "tevent_common_loop_wait() out of events\n");
645 return on failure or (with 0) if all fd events are removed
647 int _tevent_loop_wait(struct tevent_context *ev, const char *location)
649 return ev->ops->loop_wait(ev, location);
654 re-initialise a tevent context. This leaves you with the same
655 event context, but all events are wiped and the structure is
656 re-initialised. This is most useful after a fork()
658 zero is returned on success, non-zero on failure
660 int tevent_re_initialise(struct tevent_context *ev)
662 tevent_common_context_destructor(ev);
664 return ev->ops->context_init(ev);