476 lines
13 KiB
C
476 lines
13 KiB
C
/* $NetBSD: epoll.c,v 1.1.1.1 2013/04/11 16:43:19 christos Exp $ */
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/*
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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 <sys/cdefs.h>
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__RCSID("$NetBSD: epoll.c,v 1.1.1.1 2013/04/11 16:43:19 christos Exp $");
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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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#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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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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};
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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,
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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,
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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;
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struct epollop *epollop;
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/* Initialize the kernel queue. (The size field is ignored since
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* 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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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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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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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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if (1) {
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/* The logic here is a little tricky. If we had no events set
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on the fd before, we need to set op="ADD" and set
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events=the events we want to add. If we had any events set
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on the fd before, and we want any events to remain on the
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fd, we need to say op="MOD" and set events=the events we
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want to remain. But if we want to delete the last event,
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we say op="DEL" and set events=the remaining events. What
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fun!
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*/
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/* TODO: Turn this into a switch or a table lookup. */
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if ((ch->read_change & EV_CHANGE_ADD) ||
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(ch->write_change & EV_CHANGE_ADD)) {
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/* If we are adding anything at all, we'll want to do
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* either an ADD or a MOD. */
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events = 0;
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op = EPOLL_CTL_ADD;
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if (ch->read_change & EV_CHANGE_ADD) {
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events |= EPOLLIN;
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} else if (ch->read_change & EV_CHANGE_DEL) {
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;
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} else if (ch->old_events & EV_READ) {
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events |= EPOLLIN;
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}
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if (ch->write_change & EV_CHANGE_ADD) {
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events |= EPOLLOUT;
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} else if (ch->write_change & EV_CHANGE_DEL) {
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;
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} else if (ch->old_events & EV_WRITE) {
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events |= EPOLLOUT;
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}
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if ((ch->read_change|ch->write_change) & EV_ET)
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events |= EPOLLET;
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if (ch->old_events) {
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/* If MOD fails, we retry as an ADD, and if
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* ADD fails we will retry as a MOD. So the
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* only hard part here is to guess which one
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* will work. As a heuristic, we'll try
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* MOD first if we think there were old
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* events and ADD if we think there were none.
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*
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* We can be wrong about the MOD if the file
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* has in fact been closed and re-opened.
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*
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* We can be wrong about the ADD if the
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* the fd has been re-created with a dup()
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* of the same file that it was before.
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*/
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op = EPOLL_CTL_MOD;
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}
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} else if ((ch->read_change & EV_CHANGE_DEL) ||
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(ch->write_change & EV_CHANGE_DEL)) {
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/* If we're deleting anything, we'll want to do a MOD
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* or a DEL. */
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op = EPOLL_CTL_DEL;
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if (ch->read_change & EV_CHANGE_DEL) {
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if (ch->write_change & EV_CHANGE_DEL) {
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events = EPOLLIN|EPOLLOUT;
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} else if (ch->old_events & EV_WRITE) {
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events = EPOLLOUT;
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op = EPOLL_CTL_MOD;
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} else {
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events = EPOLLIN;
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}
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} else if (ch->write_change & EV_CHANGE_DEL) {
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if (ch->old_events & EV_READ) {
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events = EPOLLIN;
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op = EPOLL_CTL_MOD;
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} else {
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events = EPOLLOUT;
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}
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}
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}
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if (!events)
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return 0;
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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) == -1) {
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if (op == EPOLL_CTL_MOD && 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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}
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} else if (op == EPOLL_CTL_ADD && 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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}
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} else if (op == EPOLL_CTL_DEL &&
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(errno == ENOENT || errno == EBADF ||
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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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} else {
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event_warn("Epoll %s(%d) on fd %d failed. Old events were %d; read change was %d (%s); write change was %d (%s)",
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epoll_op_to_string(op),
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(int)epev.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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return -1;
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}
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} else {
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event_debug(("Epoll %s(%d) on fd %d okay. [old events were %d; read change was %d; write change was %d]",
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epoll_op_to_string(op),
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(int)epev.events,
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(int)ch->fd,
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ch->old_events,
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ch->read_change,
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ch->write_change));
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}
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}
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return 0;
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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 = 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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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 = 0;
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if (events & EV_WRITE)
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ch.write_change = EV_CHANGE_DEL;
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if (events & EV_READ)
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ch.read_change = EV_CHANGE_DEL;
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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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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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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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}
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if (!ev)
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continue;
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evmap_io_active(base, events[i].data.fd, ev | EV_ET);
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}
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if (res == epollop->nevents && epollop->nevents < MAX_NEVENT) {
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/* We used all of the event space this time. We should
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be ready for more events next time. */
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int new_nevents = epollop->nevents * 2;
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struct epoll_event *new_events;
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new_events = mm_realloc(epollop->events,
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new_nevents * sizeof(struct epoll_event));
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if (new_events) {
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epollop->events = new_events;
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epollop->nevents = new_nevents;
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}
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}
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return (0);
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}
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static void
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epoll_dealloc(struct event_base *base)
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{
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struct epollop *epollop = base->evbase;
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evsig_dealloc(base);
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if (epollop->events)
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mm_free(epollop->events);
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if (epollop->epfd >= 0)
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close(epollop->epfd);
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memset(epollop, 0, sizeof(struct epollop));
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mm_free(epollop);
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}
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