544 lines
14 KiB
C
544 lines
14 KiB
C
/*
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* Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
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* Copyright 2007-2012 Niels Provos, Nick Mathewson
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "event2/event-config.h"
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#include "evconfig-private.h"
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#ifdef EVENT__HAVE_EPOLL
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#include <stdint.h>
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#include <sys/types.h>
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#include <sys/resource.h>
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#ifdef EVENT__HAVE_SYS_TIME_H
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#include <sys/time.h>
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#endif
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#include <sys/queue.h>
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#include <sys/epoll.h>
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#include <signal.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#ifdef EVENT__HAVE_FCNTL_H
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#include <fcntl.h>
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#endif
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#ifdef EVENT__HAVE_SYS_TIMERFD_H
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#include <sys/timerfd.h>
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#endif
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#include "event-internal.h"
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#include "evsignal-internal.h"
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#include "event2/thread.h"
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#include "evthread-internal.h"
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#include "log-internal.h"
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#include "evmap-internal.h"
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#include "changelist-internal.h"
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#include "time-internal.h"
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/* Since Linux 2.6.17, epoll is able to report about peer half-closed connection
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using special EPOLLRDHUP flag on a read event.
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*/
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#if !defined(EPOLLRDHUP)
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#define EPOLLRDHUP 0
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#define EARLY_CLOSE_IF_HAVE_RDHUP 0
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#else
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#define EARLY_CLOSE_IF_HAVE_RDHUP EV_FEATURE_EARLY_CLOSE
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#endif
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#include "epolltable-internal.h"
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#if defined(EVENT__HAVE_SYS_TIMERFD_H) && \
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defined(EVENT__HAVE_TIMERFD_CREATE) && \
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defined(HAVE_POSIX_MONOTONIC) && defined(TFD_NONBLOCK) && \
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defined(TFD_CLOEXEC)
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/* Note that we only use timerfd if TFD_NONBLOCK and TFD_CLOEXEC are available
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and working. This means that we can't support it on 2.6.25 (where timerfd
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was introduced) or 2.6.26, since 2.6.27 introduced those flags.
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*/
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#define USING_TIMERFD
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#endif
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struct epollop {
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struct epoll_event *events;
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int nevents;
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int epfd;
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#ifdef USING_TIMERFD
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int timerfd;
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#endif
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};
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static void *epoll_init(struct event_base *);
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static int epoll_dispatch(struct event_base *, struct timeval *);
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static void epoll_dealloc(struct event_base *);
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static const struct eventop epollops_changelist = {
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"epoll (with changelist)",
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epoll_init,
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event_changelist_add_,
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event_changelist_del_,
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epoll_dispatch,
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epoll_dealloc,
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1, /* need reinit */
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EV_FEATURE_ET|EV_FEATURE_O1| EARLY_CLOSE_IF_HAVE_RDHUP,
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EVENT_CHANGELIST_FDINFO_SIZE
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};
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static int epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
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short old, short events, void *p);
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static int epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
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short old, short events, void *p);
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const struct eventop epollops = {
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"epoll",
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epoll_init,
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epoll_nochangelist_add,
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epoll_nochangelist_del,
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epoll_dispatch,
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epoll_dealloc,
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1, /* need reinit */
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EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_EARLY_CLOSE,
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0
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};
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#define INITIAL_NEVENT 32
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#define MAX_NEVENT 4096
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/* On Linux kernels at least up to 2.6.24.4, epoll can't handle timeout
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* values bigger than (LONG_MAX - 999ULL)/HZ. HZ in the wild can be
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* as big as 1000, and LONG_MAX can be as small as (1<<31)-1, so the
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* largest number of msec we can support here is 2147482. Let's
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* round that down by 47 seconds.
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*/
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#define MAX_EPOLL_TIMEOUT_MSEC (35*60*1000)
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static void *
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epoll_init(struct event_base *base)
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{
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int epfd = -1;
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struct epollop *epollop;
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#ifdef EVENT__HAVE_EPOLL_CREATE1
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/* First, try the shiny new epoll_create1 interface, if we have it. */
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epfd = epoll_create1(EPOLL_CLOEXEC);
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#endif
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if (epfd == -1) {
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/* Initialize the kernel queue using the old interface. (The
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size field is ignored since 2.6.8.) */
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if ((epfd = epoll_create(32000)) == -1) {
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if (errno != ENOSYS)
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event_warn("epoll_create");
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return (NULL);
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}
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evutil_make_socket_closeonexec(epfd);
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}
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if (!(epollop = mm_calloc(1, sizeof(struct epollop)))) {
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close(epfd);
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return (NULL);
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}
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epollop->epfd = epfd;
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/* Initialize fields */
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epollop->events = mm_calloc(INITIAL_NEVENT, sizeof(struct epoll_event));
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if (epollop->events == NULL) {
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mm_free(epollop);
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close(epfd);
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return (NULL);
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}
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epollop->nevents = INITIAL_NEVENT;
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if ((base->flags & EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST) != 0 ||
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((base->flags & EVENT_BASE_FLAG_IGNORE_ENV) == 0 &&
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evutil_getenv_("EVENT_EPOLL_USE_CHANGELIST") != NULL)) {
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base->evsel = &epollops_changelist;
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}
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#ifdef USING_TIMERFD
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/*
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The epoll interface ordinarily gives us one-millisecond precision,
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so on Linux it makes perfect sense to use the CLOCK_MONOTONIC_COARSE
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timer. But when the user has set the new PRECISE_TIMER flag for an
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event_base, we can try to use timerfd to give them finer granularity.
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*/
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if ((base->flags & EVENT_BASE_FLAG_PRECISE_TIMER) &&
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base->monotonic_timer.monotonic_clock == CLOCK_MONOTONIC) {
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int fd;
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fd = epollop->timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC);
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if (epollop->timerfd >= 0) {
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struct epoll_event epev;
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memset(&epev, 0, sizeof(epev));
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epev.data.fd = epollop->timerfd;
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epev.events = EPOLLIN;
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if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, fd, &epev) < 0) {
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event_warn("epoll_ctl(timerfd)");
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close(fd);
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epollop->timerfd = -1;
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}
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} else {
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if (errno != EINVAL && errno != ENOSYS) {
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/* These errors probably mean that we were
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* compiled with timerfd/TFD_* support, but
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* we're running on a kernel that lacks those.
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*/
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event_warn("timerfd_create");
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}
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epollop->timerfd = -1;
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}
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} else {
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epollop->timerfd = -1;
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}
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#endif
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evsig_init_(base);
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return (epollop);
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}
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static const char *
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change_to_string(int change)
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{
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change &= (EV_CHANGE_ADD|EV_CHANGE_DEL);
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if (change == EV_CHANGE_ADD) {
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return "add";
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} else if (change == EV_CHANGE_DEL) {
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return "del";
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} else if (change == 0) {
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return "none";
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} else {
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return "???";
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}
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}
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static const char *
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epoll_op_to_string(int op)
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{
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return op == EPOLL_CTL_ADD?"ADD":
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op == EPOLL_CTL_DEL?"DEL":
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op == EPOLL_CTL_MOD?"MOD":
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"???";
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}
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#define PRINT_CHANGES(op, events, ch, status) \
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"Epoll %s(%d) on fd %d " status ". " \
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"Old events were %d; " \
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"read change was %d (%s); " \
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"write change was %d (%s); " \
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"close change was %d (%s)", \
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epoll_op_to_string(op), \
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events, \
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ch->fd, \
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ch->old_events, \
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ch->read_change, \
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change_to_string(ch->read_change), \
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ch->write_change, \
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change_to_string(ch->write_change), \
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ch->close_change, \
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change_to_string(ch->close_change)
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static int
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epoll_apply_one_change(struct event_base *base,
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struct epollop *epollop,
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const struct event_change *ch)
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{
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struct epoll_event epev;
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int op, events = 0;
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int idx;
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idx = EPOLL_OP_TABLE_INDEX(ch);
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op = epoll_op_table[idx].op;
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events = epoll_op_table[idx].events;
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if (!events) {
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EVUTIL_ASSERT(op == 0);
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return 0;
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}
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if ((ch->read_change|ch->write_change) & EV_CHANGE_ET)
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events |= EPOLLET;
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memset(&epev, 0, sizeof(epev));
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epev.data.fd = ch->fd;
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epev.events = events;
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if (epoll_ctl(epollop->epfd, op, ch->fd, &epev) == 0) {
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event_debug((PRINT_CHANGES(op, epev.events, ch, "okay")));
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return 0;
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}
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switch (op) {
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case EPOLL_CTL_MOD:
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if (errno == ENOENT) {
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/* If a MOD operation fails with ENOENT, the
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* fd was probably closed and re-opened. We
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* should retry the operation as an ADD.
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*/
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if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, ch->fd, &epev) == -1) {
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event_warn("Epoll MOD(%d) on %d retried as ADD; that failed too",
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(int)epev.events, ch->fd);
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return -1;
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} else {
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event_debug(("Epoll MOD(%d) on %d retried as ADD; succeeded.",
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(int)epev.events,
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ch->fd));
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return 0;
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}
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}
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break;
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case EPOLL_CTL_ADD:
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if (errno == EEXIST) {
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/* If an ADD operation fails with EEXIST,
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* either the operation was redundant (as with a
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* precautionary add), or we ran into a fun
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* kernel bug where using dup*() to duplicate the
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* same file into the same fd gives you the same epitem
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* rather than a fresh one. For the second case,
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* we must retry with MOD. */
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if (epoll_ctl(epollop->epfd, EPOLL_CTL_MOD, ch->fd, &epev) == -1) {
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event_warn("Epoll ADD(%d) on %d retried as MOD; that failed too",
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(int)epev.events, ch->fd);
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return -1;
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} else {
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event_debug(("Epoll ADD(%d) on %d retried as MOD; succeeded.",
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(int)epev.events,
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ch->fd));
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return 0;
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}
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}
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break;
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case EPOLL_CTL_DEL:
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if (errno == ENOENT || errno == EBADF || errno == EPERM) {
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/* If a delete fails with one of these errors,
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* that's fine too: we closed the fd before we
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* got around to calling epoll_dispatch. */
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event_debug(("Epoll DEL(%d) on fd %d gave %s: DEL was unnecessary.",
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(int)epev.events,
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ch->fd,
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strerror(errno)));
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return 0;
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}
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break;
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default:
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break;
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}
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event_warn(PRINT_CHANGES(op, epev.events, ch, "failed"));
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return -1;
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}
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static int
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epoll_apply_changes(struct event_base *base)
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{
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struct event_changelist *changelist = &base->changelist;
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struct epollop *epollop = base->evbase;
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struct event_change *ch;
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int r = 0;
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int i;
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for (i = 0; i < changelist->n_changes; ++i) {
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ch = &changelist->changes[i];
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if (epoll_apply_one_change(base, epollop, ch) < 0)
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r = -1;
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}
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return (r);
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}
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static int
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epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd,
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short old, short events, void *p)
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{
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struct event_change ch;
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ch.fd = fd;
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ch.old_events = old;
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ch.read_change = ch.write_change = ch.close_change = 0;
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if (events & EV_WRITE)
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ch.write_change = EV_CHANGE_ADD |
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(events & EV_ET);
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if (events & EV_READ)
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ch.read_change = EV_CHANGE_ADD |
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(events & EV_ET);
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if (events & EV_CLOSED)
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ch.close_change = EV_CHANGE_ADD |
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(events & EV_ET);
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return epoll_apply_one_change(base, base->evbase, &ch);
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}
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static int
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epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd,
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short old, short events, void *p)
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{
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struct event_change ch;
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ch.fd = fd;
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ch.old_events = old;
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ch.read_change = ch.write_change = ch.close_change = 0;
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if (events & EV_WRITE)
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ch.write_change = EV_CHANGE_DEL |
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(events & EV_ET);
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if (events & EV_READ)
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ch.read_change = EV_CHANGE_DEL |
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(events & EV_ET);
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if (events & EV_CLOSED)
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ch.close_change = EV_CHANGE_DEL |
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(events & EV_ET);
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return epoll_apply_one_change(base, base->evbase, &ch);
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}
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static int
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epoll_dispatch(struct event_base *base, struct timeval *tv)
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{
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struct epollop *epollop = base->evbase;
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struct epoll_event *events = epollop->events;
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int i, res;
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long timeout = -1;
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#ifdef USING_TIMERFD
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if (epollop->timerfd >= 0) {
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struct itimerspec is;
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is.it_interval.tv_sec = 0;
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is.it_interval.tv_nsec = 0;
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if (tv == NULL) {
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/* No timeout; disarm the timer. */
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is.it_value.tv_sec = 0;
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is.it_value.tv_nsec = 0;
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} else {
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if (tv->tv_sec == 0 && tv->tv_usec == 0) {
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/* we need to exit immediately; timerfd can't
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* do that. */
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timeout = 0;
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}
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is.it_value.tv_sec = tv->tv_sec;
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is.it_value.tv_nsec = tv->tv_usec * 1000;
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}
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/* TODO: we could avoid unnecessary syscalls here by only
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calling timerfd_settime when the top timeout changes, or
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when we're called with a different timeval.
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*/
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if (timerfd_settime(epollop->timerfd, 0, &is, NULL) < 0) {
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event_warn("timerfd_settime");
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}
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} else
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#endif
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if (tv != NULL) {
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timeout = evutil_tv_to_msec_(tv);
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if (timeout < 0 || timeout > MAX_EPOLL_TIMEOUT_MSEC) {
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/* Linux kernels can wait forever if the timeout is
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* too big; see comment on MAX_EPOLL_TIMEOUT_MSEC. */
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timeout = MAX_EPOLL_TIMEOUT_MSEC;
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}
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}
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epoll_apply_changes(base);
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event_changelist_remove_all_(&base->changelist, base);
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EVBASE_RELEASE_LOCK(base, th_base_lock);
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res = epoll_wait(epollop->epfd, events, epollop->nevents, timeout);
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EVBASE_ACQUIRE_LOCK(base, th_base_lock);
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if (res == -1) {
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if (errno != EINTR) {
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event_warn("epoll_wait");
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return (-1);
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}
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return (0);
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}
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event_debug(("%s: epoll_wait reports %d", __func__, res));
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EVUTIL_ASSERT(res <= epollop->nevents);
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for (i = 0; i < res; i++) {
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int what = events[i].events;
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short ev = 0;
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#ifdef USING_TIMERFD
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if (events[i].data.fd == epollop->timerfd)
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continue;
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#endif
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if (what & (EPOLLHUP|EPOLLERR)) {
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ev = EV_READ | EV_WRITE;
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} else {
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if (what & EPOLLIN)
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ev |= EV_READ;
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if (what & EPOLLOUT)
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ev |= EV_WRITE;
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if (what & EPOLLRDHUP)
|
|
ev |= EV_CLOSED;
|
|
}
|
|
|
|
if (!ev)
|
|
continue;
|
|
|
|
evmap_io_active_(base, events[i].data.fd, ev | EV_ET);
|
|
}
|
|
|
|
if (res == epollop->nevents && epollop->nevents < MAX_NEVENT) {
|
|
/* We used all of the event space this time. We should
|
|
be ready for more events next time. */
|
|
int new_nevents = epollop->nevents * 2;
|
|
struct epoll_event *new_events;
|
|
|
|
new_events = mm_realloc(epollop->events,
|
|
new_nevents * sizeof(struct epoll_event));
|
|
if (new_events) {
|
|
epollop->events = new_events;
|
|
epollop->nevents = new_nevents;
|
|
}
|
|
}
|
|
|
|
return (0);
|
|
}
|
|
|
|
|
|
static void
|
|
epoll_dealloc(struct event_base *base)
|
|
{
|
|
struct epollop *epollop = base->evbase;
|
|
|
|
evsig_dealloc_(base);
|
|
if (epollop->events)
|
|
mm_free(epollop->events);
|
|
if (epollop->epfd >= 0)
|
|
close(epollop->epfd);
|
|
#ifdef USING_TIMERFD
|
|
if (epollop->timerfd >= 0)
|
|
close(epollop->timerfd);
|
|
#endif
|
|
|
|
memset(epollop, 0, sizeof(struct epollop));
|
|
mm_free(epollop);
|
|
}
|
|
|
|
#endif /* EVENT__HAVE_EPOLL */
|