source: trunk/server/lib/tevent/tevent_epoll.c

Last change on this file was 745, checked in by Silvan Scherrer, 13 years ago

Samba Server: updated trunk to 3.6.0
File size: 11.8 KB
Line 
1/*
2 Unix SMB/CIFS implementation.
3
4 main select loop and event handling - epoll implementation
5
6 Copyright (C) Andrew Tridgell 2003-2005
7 Copyright (C) Stefan Metzmacher 2005-2009
8
9 ** NOTE! The following LGPL license applies to the tevent
10 ** library. This does NOT imply that all of Samba is released
11 ** under the LGPL
12
13 This library is free software; you can redistribute it and/or
14 modify it under the terms of the GNU Lesser General Public
15 License as published by the Free Software Foundation; either
16 version 3 of the License, or (at your option) any later version.
17
18 This library is distributed in the hope that it will be useful,
19 but WITHOUT ANY WARRANTY; without even the implied warranty of
20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 Lesser General Public License for more details.
22
23 You should have received a copy of the GNU Lesser General Public
24 License along with this library; if not, see <http://www.gnu.org/licenses/>.
25*/
26
27#include "replace.h"
28#include "system/filesys.h"
29#include "system/select.h"
30#include "tevent.h"
31#include "tevent_internal.h"
32#include "tevent_util.h"
33
34struct epoll_event_context {
35 /* a pointer back to the generic event_context */
36 struct tevent_context *ev;
37
38 /* when using epoll this is the handle from epoll_create */
39 int epoll_fd;
40
41 pid_t pid;
42};
43
44/*
45 called when a epoll call fails
46*/
47static void epoll_panic(struct epoll_event_context *epoll_ev, const char *reason)
48{
49 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
50 "%s (%s) - calling abort()\n", reason, strerror(errno));
51 abort();
52}
53
54/*
55 map from TEVENT_FD_* to EPOLLIN/EPOLLOUT
56*/
57static uint32_t epoll_map_flags(uint16_t flags)
58{
59 uint32_t ret = 0;
60 if (flags & TEVENT_FD_READ) ret |= (EPOLLIN | EPOLLERR | EPOLLHUP);
61 if (flags & TEVENT_FD_WRITE) ret |= (EPOLLOUT | EPOLLERR | EPOLLHUP);
62 return ret;
63}
64
65/*
66 free the epoll fd
67*/
68static int epoll_ctx_destructor(struct epoll_event_context *epoll_ev)
69{
70 close(epoll_ev->epoll_fd);
71 epoll_ev->epoll_fd = -1;
72 return 0;
73}
74
75/*
76 init the epoll fd
77*/
78static int epoll_init_ctx(struct epoll_event_context *epoll_ev)
79{
80 epoll_ev->epoll_fd = epoll_create(64);
81 epoll_ev->pid = getpid();
82 talloc_set_destructor(epoll_ev, epoll_ctx_destructor);
83 if (epoll_ev->epoll_fd == -1) {
84 return -1;
85 }
86 return 0;
87}
88
89static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde);
90
91/*
92 reopen the epoll handle when our pid changes
93 see http://junkcode.samba.org/ftp/unpacked/junkcode/epoll_fork.c for an
94 demonstration of why this is needed
95 */
96static void epoll_check_reopen(struct epoll_event_context *epoll_ev)
97{
98 struct tevent_fd *fde;
99
100 if (epoll_ev->pid == getpid()) {
101 return;
102 }
103
104 close(epoll_ev->epoll_fd);
105 epoll_ev->epoll_fd = epoll_create(64);
106 if (epoll_ev->epoll_fd == -1) {
107 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
108 "Failed to recreate epoll handle after fork\n");
109 return;
110 }
111 epoll_ev->pid = getpid();
112 for (fde=epoll_ev->ev->fd_events;fde;fde=fde->next) {
113 epoll_add_event(epoll_ev, fde);
114 }
115}
116
117#define EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT (1<<0)
118#define EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR (1<<1)
119#define EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR (1<<2)
120
121/*
122 add the epoll event to the given fd_event
123*/
124static void epoll_add_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
125{
126 struct epoll_event event;
127
128 if (epoll_ev->epoll_fd == -1) return;
129
130 fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
131
132 /* if we don't want events yet, don't add an epoll_event */
133 if (fde->flags == 0) return;
134
135 ZERO_STRUCT(event);
136 event.events = epoll_map_flags(fde->flags);
137 event.data.ptr = fde;
138 if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_ADD, fde->fd, &event) != 0) {
139 epoll_panic(epoll_ev, "EPOLL_CTL_ADD failed");
140 }
141 fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
142
143 /* only if we want to read we want to tell the event handler about errors */
144 if (fde->flags & TEVENT_FD_READ) {
145 fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
146 }
147}
148
149/*
150 delete the epoll event for given fd_event
151*/
152static void epoll_del_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
153{
154 struct epoll_event event;
155
156 if (epoll_ev->epoll_fd == -1) return;
157
158 fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
159
160 /* if there's no epoll_event, we don't need to delete it */
161 if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT)) return;
162
163 ZERO_STRUCT(event);
164 event.events = epoll_map_flags(fde->flags);
165 event.data.ptr = fde;
166 if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_DEL, fde->fd, &event) != 0) {
167 tevent_debug(epoll_ev->ev, TEVENT_DEBUG_FATAL,
168 "epoll_del_event failed! probable early close bug (%s)\n",
169 strerror(errno));
170 }
171 fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT;
172}
173
174/*
175 change the epoll event to the given fd_event
176*/
177static void epoll_mod_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
178{
179 struct epoll_event event;
180 if (epoll_ev->epoll_fd == -1) return;
181
182 fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
183
184 ZERO_STRUCT(event);
185 event.events = epoll_map_flags(fde->flags);
186 event.data.ptr = fde;
187 if (epoll_ctl(epoll_ev->epoll_fd, EPOLL_CTL_MOD, fde->fd, &event) != 0) {
188 epoll_panic(epoll_ev, "EPOLL_CTL_MOD failed");
189 }
190
191 /* only if we want to read we want to tell the event handler about errors */
192 if (fde->flags & TEVENT_FD_READ) {
193 fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
194 }
195}
196
197static void epoll_change_event(struct epoll_event_context *epoll_ev, struct tevent_fd *fde)
198{
199 bool got_error = (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR);
200 bool want_read = (fde->flags & TEVENT_FD_READ);
201 bool want_write= (fde->flags & TEVENT_FD_WRITE);
202
203 if (epoll_ev->epoll_fd == -1) return;
204
205 fde->additional_flags &= ~EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR;
206
207 /* there's already an event */
208 if (fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_HAS_EVENT) {
209 if (want_read || (want_write && !got_error)) {
210 epoll_mod_event(epoll_ev, fde);
211 return;
212 }
213 /*
214 * if we want to match the select behavior, we need to remove the epoll_event
215 * when the caller isn't interested in events.
216 *
217 * this is because epoll reports EPOLLERR and EPOLLHUP, even without asking for them
218 */
219 epoll_del_event(epoll_ev, fde);
220 return;
221 }
222
223 /* there's no epoll_event attached to the fde */
224 if (want_read || (want_write && !got_error)) {
225 epoll_add_event(epoll_ev, fde);
226 return;
227 }
228}
229
230/*
231 event loop handling using epoll
232*/
233static int epoll_event_loop(struct epoll_event_context *epoll_ev, struct timeval *tvalp)
234{
235 int ret, i;
236#define MAXEVENTS 1
237 struct epoll_event events[MAXEVENTS];
238 int timeout = -1;
239
240 if (epoll_ev->epoll_fd == -1) return -1;
241
242 if (tvalp) {
243 /* it's better to trigger timed events a bit later than to early */
244 timeout = ((tvalp->tv_usec+999) / 1000) + (tvalp->tv_sec*1000);
245 }
246
247 if (epoll_ev->ev->signal_events &&
248 tevent_common_check_signal(epoll_ev->ev)) {
249 return 0;
250 }
251
252 ret = epoll_wait(epoll_ev->epoll_fd, events, MAXEVENTS, timeout);
253
254 if (ret == -1 && errno == EINTR && epoll_ev->ev->signal_events) {
255 if (tevent_common_check_signal(epoll_ev->ev)) {
256 return 0;
257 }
258 }
259
260 if (ret == -1 && errno != EINTR) {
261 epoll_panic(epoll_ev, "epoll_wait() failed");
262 return -1;
263 }
264
265 if (ret == 0 && tvalp) {
266 /* we don't care about a possible delay here */
267 tevent_common_loop_timer_delay(epoll_ev->ev);
268 return 0;
269 }
270
271 for (i=0;i<ret;i++) {
272 struct tevent_fd *fde = talloc_get_type(events[i].data.ptr,
273 struct tevent_fd);
274 uint16_t flags = 0;
275
276 if (fde == NULL) {
277 epoll_panic(epoll_ev, "epoll_wait() gave bad data");
278 return -1;
279 }
280 if (events[i].events & (EPOLLHUP|EPOLLERR)) {
281 fde->additional_flags |= EPOLL_ADDITIONAL_FD_FLAG_GOT_ERROR;
282 /*
283 * if we only wait for TEVENT_FD_WRITE, we should not tell the
284 * event handler about it, and remove the epoll_event,
285 * as we only report errors when waiting for read events,
286 * to match the select() behavior
287 */
288 if (!(fde->additional_flags & EPOLL_ADDITIONAL_FD_FLAG_REPORT_ERROR)) {
289 epoll_del_event(epoll_ev, fde);
290 continue;
291 }
292 flags |= TEVENT_FD_READ;
293 }
294 if (events[i].events & EPOLLIN) flags |= TEVENT_FD_READ;
295 if (events[i].events & EPOLLOUT) flags |= TEVENT_FD_WRITE;
296 if (flags) {
297 fde->handler(epoll_ev->ev, fde, flags, fde->private_data);
298 break;
299 }
300 }
301
302 return 0;
303}
304
305/*
306 create a epoll_event_context structure.
307*/
308static int epoll_event_context_init(struct tevent_context *ev)
309{
310 int ret;
311 struct epoll_event_context *epoll_ev;
312
313 epoll_ev = talloc_zero(ev, struct epoll_event_context);
314 if (!epoll_ev) return -1;
315 epoll_ev->ev = ev;
316 epoll_ev->epoll_fd = -1;
317
318 ret = epoll_init_ctx(epoll_ev);
319 if (ret != 0) {
320 talloc_free(epoll_ev);
321 return ret;
322 }
323
324 ev->additional_data = epoll_ev;
325 return 0;
326}
327
328/*
329 destroy an fd_event
330*/
331static int epoll_event_fd_destructor(struct tevent_fd *fde)
332{
333 struct tevent_context *ev = fde->event_ctx;
334 struct epoll_event_context *epoll_ev = NULL;
335
336 if (ev) {
337 epoll_ev = talloc_get_type(ev->additional_data,
338 struct epoll_event_context);
339
340 epoll_check_reopen(epoll_ev);
341
342 epoll_del_event(epoll_ev, fde);
343 }
344
345 return tevent_common_fd_destructor(fde);
346}
347
348/*
349 add a fd based event
350 return NULL on failure (memory allocation error)
351*/
352static struct tevent_fd *epoll_event_add_fd(struct tevent_context *ev, TALLOC_CTX *mem_ctx,
353 int fd, uint16_t flags,
354 tevent_fd_handler_t handler,
355 void *private_data,
356 const char *handler_name,
357 const char *location)
358{
359 struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
360 struct epoll_event_context);
361 struct tevent_fd *fde;
362
363 epoll_check_reopen(epoll_ev);
364
365 fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
366 handler, private_data,
367 handler_name, location);
368 if (!fde) return NULL;
369
370 talloc_set_destructor(fde, epoll_event_fd_destructor);
371
372 epoll_add_event(epoll_ev, fde);
373
374 return fde;
375}
376
377/*
378 set the fd event flags
379*/
380static void epoll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
381{
382 struct tevent_context *ev;
383 struct epoll_event_context *epoll_ev;
384
385 if (fde->flags == flags) return;
386
387 ev = fde->event_ctx;
388 epoll_ev = talloc_get_type(ev->additional_data, struct epoll_event_context);
389
390 fde->flags = flags;
391
392 epoll_check_reopen(epoll_ev);
393
394 epoll_change_event(epoll_ev, fde);
395}
396
397/*
398 do a single event loop using the events defined in ev
399*/
400static int epoll_event_loop_once(struct tevent_context *ev, const char *location)
401{
402 struct epoll_event_context *epoll_ev = talloc_get_type(ev->additional_data,
403 struct epoll_event_context);
404 struct timeval tval;
405
406 if (ev->signal_events &&
407 tevent_common_check_signal(ev)) {
408 return 0;
409 }
410
411 if (ev->immediate_events &&
412 tevent_common_loop_immediate(ev)) {
413 return 0;
414 }
415
416 tval = tevent_common_loop_timer_delay(ev);
417 if (tevent_timeval_is_zero(&tval)) {
418 return 0;
419 }
420
421 epoll_check_reopen(epoll_ev);
422
423 return epoll_event_loop(epoll_ev, &tval);
424}
425
426static const struct tevent_ops epoll_event_ops = {
427 .context_init = epoll_event_context_init,
428 .add_fd = epoll_event_add_fd,
429 .set_fd_close_fn = tevent_common_fd_set_close_fn,
430 .get_fd_flags = tevent_common_fd_get_flags,
431 .set_fd_flags = epoll_event_set_fd_flags,
432 .add_timer = tevent_common_add_timer,
433 .schedule_immediate = tevent_common_schedule_immediate,
434 .add_signal = tevent_common_add_signal,
435 .loop_once = epoll_event_loop_once,
436 .loop_wait = tevent_common_loop_wait,
437};
438
439_PRIVATE_ bool tevent_epoll_init(void)
440{
441 return tevent_register_backend("epoll", &epoll_event_ops);
442}
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