2 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
3 * Copyright 2007-2012 Niels Provos, Nick Mathewson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 #include "event2/event-config.h"
28 #include "evconfig-private.h"
30 #ifdef EVENT__HAVE_EPOLL
33 #include <sys/types.h>
34 #include <sys/resource.h>
35 #ifdef EVENT__HAVE_SYS_TIME_H
38 #include <sys/queue.h>
39 #include <sys/epoll.h>
47 #ifdef EVENT__HAVE_FCNTL_H
50 #ifdef EVENT__HAVE_SYS_TIMERFD_H
51 #include <sys/timerfd.h>
54 #include "event-internal.h"
55 #include "evsignal-internal.h"
56 #include "event2/thread.h"
57 #include "evthread-internal.h"
58 #include "log-internal.h"
59 #include "evmap-internal.h"
60 #include "changelist-internal.h"
61 #include "time-internal.h"
63 /* Since Linux 2.6.17, epoll is able to report about peer half-closed connection
64 using special EPOLLRDHUP flag on a read event.
66 #if !defined(EPOLLRDHUP)
68 #define EARLY_CLOSE_IF_HAVE_RDHUP 0
70 #define EARLY_CLOSE_IF_HAVE_RDHUP EV_FEATURE_EARLY_CLOSE
73 #include "epolltable-internal.h"
75 #if defined(EVENT__HAVE_SYS_TIMERFD_H) && \
76 defined(EVENT__HAVE_TIMERFD_CREATE) && \
77 defined(HAVE_POSIX_MONOTONIC) && defined(TFD_NONBLOCK) && \
79 /* Note that we only use timerfd if TFD_NONBLOCK and TFD_CLOEXEC are available
80 and working. This means that we can't support it on 2.6.25 (where timerfd
81 was introduced) or 2.6.26, since 2.6.27 introduced those flags.
87 struct epoll_event *events;
95 static void *epoll_init(struct event_base *);
96 static int epoll_dispatch(struct event_base *, struct timeval *);
97 static void epoll_dealloc(struct event_base *);
99 static const struct eventop epollops_changelist = {
100 "epoll (with changelist)",
102 event_changelist_add_,
103 event_changelist_del_,
107 EV_FEATURE_ET|EV_FEATURE_O1| EARLY_CLOSE_IF_HAVE_RDHUP,
108 EVENT_CHANGELIST_FDINFO_SIZE
112 static int epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
113 short old, short events, void *p);
114 static int epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
115 short old, short events, void *p);
117 const struct eventop epollops = {
120 epoll_nochangelist_add,
121 epoll_nochangelist_del,
125 EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_EARLY_CLOSE,
129 #define INITIAL_NEVENT 32
130 #define MAX_NEVENT 4096
132 /* On Linux kernels at least up to 2.6.24.4, epoll can't handle timeout
133 * values bigger than (LONG_MAX - 999ULL)/HZ. HZ in the wild can be
134 * as big as 1000, and LONG_MAX can be as small as (1<<31)-1, so the
135 * largest number of msec we can support here is 2147482. Let's
136 * round that down by 47 seconds.
138 #define MAX_EPOLL_TIMEOUT_MSEC (35*60*1000)
141 epoll_init(struct event_base *base)
144 struct epollop *epollop;
146 #ifdef EVENT__HAVE_EPOLL_CREATE1
147 /* First, try the shiny new epoll_create1 interface, if we have it. */
148 epfd = epoll_create1(EPOLL_CLOEXEC);
151 /* Initialize the kernel queue using the old interface. (The
152 size field is ignored since 2.6.8.) */
153 if ((epfd = epoll_create(32000)) == -1) {
155 event_warn("epoll_create");
158 evutil_make_socket_closeonexec(epfd);
161 if (!(epollop = mm_calloc(1, sizeof(struct epollop)))) {
166 epollop->epfd = epfd;
168 /* Initialize fields */
169 epollop->events = mm_calloc(INITIAL_NEVENT, sizeof(struct epoll_event));
170 if (epollop->events == NULL) {
175 epollop->nevents = INITIAL_NEVENT;
177 if ((base->flags & EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST) != 0 ||
178 ((base->flags & EVENT_BASE_FLAG_IGNORE_ENV) == 0 &&
179 evutil_getenv_("EVENT_EPOLL_USE_CHANGELIST") != NULL)) {
181 base->evsel = &epollops_changelist;
186 The epoll interface ordinarily gives us one-millisecond precision,
187 so on Linux it makes perfect sense to use the CLOCK_MONOTONIC_COARSE
188 timer. But when the user has set the new PRECISE_TIMER flag for an
189 event_base, we can try to use timerfd to give them finer granularity.
191 if ((base->flags & EVENT_BASE_FLAG_PRECISE_TIMER) &&
192 base->monotonic_timer.monotonic_clock == CLOCK_MONOTONIC) {
194 fd = epollop->timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC);
195 if (epollop->timerfd >= 0) {
196 struct epoll_event epev;
197 memset(&epev, 0, sizeof(epev));
198 epev.data.fd = epollop->timerfd;
199 epev.events = EPOLLIN;
200 if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, fd, &epev) < 0) {
201 event_warn("epoll_ctl(timerfd)");
203 epollop->timerfd = -1;
206 if (errno != EINVAL && errno != ENOSYS) {
207 /* These errors probably mean that we were
208 * compiled with timerfd/TFD_* support, but
209 * we're running on a kernel that lacks those.
211 event_warn("timerfd_create");
213 epollop->timerfd = -1;
216 epollop->timerfd = -1;
226 change_to_string(int change)
228 change &= (EV_CHANGE_ADD|EV_CHANGE_DEL);
229 if (change == EV_CHANGE_ADD) {
231 } else if (change == EV_CHANGE_DEL) {
233 } else if (change == 0) {
241 epoll_op_to_string(int op)
243 return op == EPOLL_CTL_ADD?"ADD":
244 op == EPOLL_CTL_DEL?"DEL":
245 op == EPOLL_CTL_MOD?"MOD":
249 #define PRINT_CHANGES(op, events, ch, status) \
250 "Epoll %s(%d) on fd %d " status ". " \
251 "Old events were %d; " \
252 "read change was %d (%s); " \
253 "write change was %d (%s); " \
254 "close change was %d (%s)", \
255 epoll_op_to_string(op), \
260 change_to_string(ch->read_change), \
262 change_to_string(ch->write_change), \
264 change_to_string(ch->close_change)
267 epoll_apply_one_change(struct event_base *base,
268 struct epollop *epollop,
269 const struct event_change *ch)
271 struct epoll_event epev;
275 idx = EPOLL_OP_TABLE_INDEX(ch);
276 op = epoll_op_table[idx].op;
277 events = epoll_op_table[idx].events;
280 EVUTIL_ASSERT(op == 0);
284 if ((ch->read_change|ch->write_change) & EV_CHANGE_ET)
287 memset(&epev, 0, sizeof(epev));
288 epev.data.fd = ch->fd;
289 epev.events = events;
290 if (epoll_ctl(epollop->epfd, op, ch->fd, &epev) == 0) {
291 event_debug((PRINT_CHANGES(op, epev.events, ch, "okay")));
297 if (errno == ENOENT) {
298 /* If a MOD operation fails with ENOENT, the
299 * fd was probably closed and re-opened. We
300 * should retry the operation as an ADD.
302 if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, ch->fd, &epev) == -1) {
303 event_warn("Epoll MOD(%d) on %d retried as ADD; that failed too",
304 (int)epev.events, ch->fd);
307 event_debug(("Epoll MOD(%d) on %d retried as ADD; succeeded.",
315 if (errno == EEXIST) {
316 /* If an ADD operation fails with EEXIST,
317 * either the operation was redundant (as with a
318 * precautionary add), or we ran into a fun
319 * kernel bug where using dup*() to duplicate the
320 * same file into the same fd gives you the same epitem
321 * rather than a fresh one. For the second case,
322 * we must retry with MOD. */
323 if (epoll_ctl(epollop->epfd, EPOLL_CTL_MOD, ch->fd, &epev) == -1) {
324 event_warn("Epoll ADD(%d) on %d retried as MOD; that failed too",
325 (int)epev.events, ch->fd);
328 event_debug(("Epoll ADD(%d) on %d retried as MOD; succeeded.",
336 if (errno == ENOENT || errno == EBADF || errno == EPERM) {
337 /* If a delete fails with one of these errors,
338 * that's fine too: we closed the fd before we
339 * got around to calling epoll_dispatch. */
340 event_debug(("Epoll DEL(%d) on fd %d gave %s: DEL was unnecessary.",
351 event_warn(PRINT_CHANGES(op, epev.events, ch, "failed"));
356 epoll_apply_changes(struct event_base *base)
358 struct event_changelist *changelist = &base->changelist;
359 struct epollop *epollop = base->evbase;
360 struct event_change *ch;
365 for (i = 0; i < changelist->n_changes; ++i) {
366 ch = &changelist->changes[i];
367 if (epoll_apply_one_change(base, epollop, ch) < 0)
375 epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
376 short old, short events, void *p)
378 struct event_change ch;
381 ch.read_change = ch.write_change = ch.close_change = 0;
382 if (events & EV_WRITE)
383 ch.write_change = EV_CHANGE_ADD |
385 if (events & EV_READ)
386 ch.read_change = EV_CHANGE_ADD |
388 if (events & EV_CLOSED)
389 ch.close_change = EV_CHANGE_ADD |
392 return epoll_apply_one_change(base, base->evbase, &ch);
396 epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
397 short old, short events, void *p)
399 struct event_change ch;
402 ch.read_change = ch.write_change = ch.close_change = 0;
403 if (events & EV_WRITE)
404 ch.write_change = EV_CHANGE_DEL |
406 if (events & EV_READ)
407 ch.read_change = EV_CHANGE_DEL |
409 if (events & EV_CLOSED)
410 ch.close_change = EV_CHANGE_DEL |
413 return epoll_apply_one_change(base, base->evbase, &ch);
417 epoll_dispatch(struct event_base *base, struct timeval *tv)
419 struct epollop *epollop = base->evbase;
420 struct epoll_event *events = epollop->events;
425 if (epollop->timerfd >= 0) {
426 struct itimerspec is;
427 is.it_interval.tv_sec = 0;
428 is.it_interval.tv_nsec = 0;
430 /* No timeout; disarm the timer. */
431 is.it_value.tv_sec = 0;
432 is.it_value.tv_nsec = 0;
434 if (tv->tv_sec == 0 && tv->tv_usec == 0) {
435 /* we need to exit immediately; timerfd can't
439 is.it_value.tv_sec = tv->tv_sec;
440 is.it_value.tv_nsec = tv->tv_usec * 1000;
442 /* TODO: we could avoid unnecessary syscalls here by only
443 calling timerfd_settime when the top timeout changes, or
444 when we're called with a different timeval.
446 if (timerfd_settime(epollop->timerfd, 0, &is, NULL) < 0) {
447 event_warn("timerfd_settime");
452 timeout = evutil_tv_to_msec_(tv);
453 if (timeout < 0 || timeout > MAX_EPOLL_TIMEOUT_MSEC) {
454 /* Linux kernels can wait forever if the timeout is
455 * too big; see comment on MAX_EPOLL_TIMEOUT_MSEC. */
456 timeout = MAX_EPOLL_TIMEOUT_MSEC;
460 epoll_apply_changes(base);
461 event_changelist_remove_all_(&base->changelist, base);
463 EVBASE_RELEASE_LOCK(base, th_base_lock);
465 res = epoll_wait(epollop->epfd, events, epollop->nevents, timeout);
467 EVBASE_ACQUIRE_LOCK(base, th_base_lock);
470 if (errno != EINTR) {
471 event_warn("epoll_wait");
478 event_debug(("%s: epoll_wait reports %d", __func__, res));
479 EVUTIL_ASSERT(res <= epollop->nevents);
481 for (i = 0; i < res; i++) {
482 int what = events[i].events;
485 if (events[i].data.fd == epollop->timerfd)
489 if (what & (EPOLLHUP|EPOLLERR)) {
490 ev = EV_READ | EV_WRITE;
496 if (what & EPOLLRDHUP)
503 evmap_io_active_(base, events[i].data.fd, ev | EV_ET);
506 if (res == epollop->nevents && epollop->nevents < MAX_NEVENT) {
507 /* We used all of the event space this time. We should
508 be ready for more events next time. */
509 int new_nevents = epollop->nevents * 2;
510 struct epoll_event *new_events;
512 new_events = mm_realloc(epollop->events,
513 new_nevents * sizeof(struct epoll_event));
515 epollop->events = new_events;
516 epollop->nevents = new_nevents;
525 epoll_dealloc(struct event_base *base)
527 struct epollop *epollop = base->evbase;
529 evsig_dealloc_(base);
531 mm_free(epollop->events);
532 if (epollop->epfd >= 0)
533 close(epollop->epfd);
535 if (epollop->timerfd >= 0)
536 close(epollop->timerfd);
539 memset(epollop, 0, sizeof(struct epollop));
543 #endif /* EVENT__HAVE_EPOLL */