diff options
Diffstat (limited to 'sntp/libevent/epoll.c')
| -rw-r--r-- | sntp/libevent/epoll.c | 541 |
1 files changed, 541 insertions, 0 deletions
diff --git a/sntp/libevent/epoll.c b/sntp/libevent/epoll.c new file mode 100644 index 0000000..aa41f84 --- /dev/null +++ b/sntp/libevent/epoll.c @@ -0,0 +1,541 @@ +/* + * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu> + * Copyright 2007-2012 Niels Provos, Nick Mathewson + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#include "event2/event-config.h" +#include "evconfig-private.h" + +#ifdef EVENT__HAVE_EPOLL + +#include <stdint.h> +#include <sys/types.h> +#include <sys/resource.h> +#ifdef EVENT__HAVE_SYS_TIME_H +#include <sys/time.h> +#endif +#include <sys/queue.h> +#include <sys/epoll.h> +#include <signal.h> +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> +#ifdef EVENT__HAVE_FCNTL_H +#include <fcntl.h> +#endif +#ifdef EVENT__HAVE_SYS_TIMERFD_H +#include <sys/timerfd.h> +#endif + +#include "event-internal.h" +#include "evsignal-internal.h" +#include "event2/thread.h" +#include "evthread-internal.h" +#include "log-internal.h" +#include "evmap-internal.h" +#include "changelist-internal.h" +#include "time-internal.h" + +/* Since Linux 2.6.17, epoll is able to report about peer half-closed connection + using special EPOLLRDHUP flag on a read event. +*/ +#if !defined(EPOLLRDHUP) +#define EPOLLRDHUP 0 +#define EARLY_CLOSE_IF_HAVE_RDHUP 0 +#else +#define EARLY_CLOSE_IF_HAVE_RDHUP EV_FEATURE_EARLY_CLOSE +#endif + +#include "epolltable-internal.h" + +#if defined(EVENT__HAVE_SYS_TIMERFD_H) && \ + defined(EVENT__HAVE_TIMERFD_CREATE) && \ + defined(HAVE_POSIX_MONOTONIC) && defined(TFD_NONBLOCK) && \ + defined(TFD_CLOEXEC) +/* Note that we only use timerfd if TFD_NONBLOCK and TFD_CLOEXEC are available + and working. This means that we can't support it on 2.6.25 (where timerfd + was introduced) or 2.6.26, since 2.6.27 introduced those flags. + */ +#define USING_TIMERFD +#endif + +struct epollop { + struct epoll_event *events; + int nevents; + int epfd; +#ifdef USING_TIMERFD + int timerfd; +#endif +}; + +static void *epoll_init(struct event_base *); +static int epoll_dispatch(struct event_base *, struct timeval *); +static void epoll_dealloc(struct event_base *); + +static const struct eventop epollops_changelist = { + "epoll (with changelist)", + epoll_init, + event_changelist_add_, + event_changelist_del_, + epoll_dispatch, + epoll_dealloc, + 1, /* need reinit */ + EV_FEATURE_ET|EV_FEATURE_O1| EARLY_CLOSE_IF_HAVE_RDHUP, + EVENT_CHANGELIST_FDINFO_SIZE +}; + + +static int epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd, + short old, short events, void *p); +static int epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd, + short old, short events, void *p); + +const struct eventop epollops = { + "epoll", + epoll_init, + epoll_nochangelist_add, + epoll_nochangelist_del, + epoll_dispatch, + epoll_dealloc, + 1, /* need reinit */ + EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_EARLY_CLOSE, + 0 +}; + +#define INITIAL_NEVENT 32 +#define MAX_NEVENT 4096 + +/* On Linux kernels at least up to 2.6.24.4, epoll can't handle timeout + * values bigger than (LONG_MAX - 999ULL)/HZ. HZ in the wild can be + * as big as 1000, and LONG_MAX can be as small as (1<<31)-1, so the + * largest number of msec we can support here is 2147482. Let's + * round that down by 47 seconds. + */ +#define MAX_EPOLL_TIMEOUT_MSEC (35*60*1000) + +static void * +epoll_init(struct event_base *base) +{ + int epfd = -1; + struct epollop *epollop; + +#ifdef EVENT__HAVE_EPOLL_CREATE1 + /* First, try the shiny new epoll_create1 interface, if we have it. */ + epfd = epoll_create1(EPOLL_CLOEXEC); +#endif + if (epfd == -1) { + /* Initialize the kernel queue using the old interface. (The + size field is ignored since 2.6.8.) */ + if ((epfd = epoll_create(32000)) == -1) { + if (errno != ENOSYS) + event_warn("epoll_create"); + return (NULL); + } + evutil_make_socket_closeonexec(epfd); + } + + if (!(epollop = mm_calloc(1, sizeof(struct epollop)))) { + close(epfd); + return (NULL); + } + + epollop->epfd = epfd; + + /* Initialize fields */ + epollop->events = mm_calloc(INITIAL_NEVENT, sizeof(struct epoll_event)); + if (epollop->events == NULL) { + mm_free(epollop); + close(epfd); + return (NULL); + } + epollop->nevents = INITIAL_NEVENT; + + if ((base->flags & EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST) != 0 || + ((base->flags & EVENT_BASE_FLAG_IGNORE_ENV) == 0 && + evutil_getenv_("EVENT_EPOLL_USE_CHANGELIST") != NULL)) { + + base->evsel = &epollops_changelist; + } + +#ifdef USING_TIMERFD + /* + The epoll interface ordinarily gives us one-millisecond precision, + so on Linux it makes perfect sense to use the CLOCK_MONOTONIC_COARSE + timer. But when the user has set the new PRECISE_TIMER flag for an + event_base, we can try to use timerfd to give them finer granularity. + */ + if ((base->flags & EVENT_BASE_FLAG_PRECISE_TIMER) && + base->monotonic_timer.monotonic_clock == CLOCK_MONOTONIC) { + int fd; + fd = epollop->timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC); + if (epollop->timerfd >= 0) { + struct epoll_event epev; + memset(&epev, 0, sizeof(epev)); + epev.data.fd = epollop->timerfd; + epev.events = EPOLLIN; + if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, fd, &epev) < 0) { + event_warn("epoll_ctl(timerfd)"); + close(fd); + epollop->timerfd = -1; + } + } else { + if (errno != EINVAL && errno != ENOSYS) { + /* These errors probably mean that we were + * compiled with timerfd/TFD_* support, but + * we're running on a kernel that lacks those. + */ + event_warn("timerfd_create"); + } + epollop->timerfd = -1; + } + } else { + epollop->timerfd = -1; + } +#endif + + evsig_init_(base); + + return (epollop); +} + +static const char * +change_to_string(int change) +{ + change &= (EV_CHANGE_ADD|EV_CHANGE_DEL); + if (change == EV_CHANGE_ADD) { + return "add"; + } else if (change == EV_CHANGE_DEL) { + return "del"; + } else if (change == 0) { + return "none"; + } else { + return "???"; + } +} + +static const char * +epoll_op_to_string(int op) +{ + return op == EPOLL_CTL_ADD?"ADD": + op == EPOLL_CTL_DEL?"DEL": + op == EPOLL_CTL_MOD?"MOD": + "???"; +} + +static int +epoll_apply_one_change(struct event_base *base, + struct epollop *epollop, + const struct event_change *ch) +{ + struct epoll_event epev; + int op, events = 0; + int idx; + + idx = EPOLL_OP_TABLE_INDEX(ch); + op = epoll_op_table[idx].op; + events = epoll_op_table[idx].events; + + if (!events) { + EVUTIL_ASSERT(op == 0); + return 0; + } + + if ((ch->read_change|ch->write_change) & EV_CHANGE_ET) + events |= EPOLLET; + + memset(&epev, 0, sizeof(epev)); + epev.data.fd = ch->fd; + epev.events = events; + if (epoll_ctl(epollop->epfd, op, ch->fd, &epev) == 0) { + event_debug(("Epoll %s(%d) on fd %d okay. [old events were %d; read change was %d; write change was %d; close change was %d]", + epoll_op_to_string(op), + (int)epev.events, + (int)ch->fd, + ch->old_events, + ch->read_change, + ch->write_change, + ch->close_change)); + return 0; + } + + switch (op) { + case EPOLL_CTL_MOD: + if (errno == ENOENT) { + /* If a MOD operation fails with ENOENT, the + * fd was probably closed and re-opened. We + * should retry the operation as an ADD. + */ + if (epoll_ctl(epollop->epfd, EPOLL_CTL_ADD, ch->fd, &epev) == -1) { + event_warn("Epoll MOD(%d) on %d retried as ADD; that failed too", + (int)epev.events, ch->fd); + return -1; + } else { + event_debug(("Epoll MOD(%d) on %d retried as ADD; succeeded.", + (int)epev.events, + ch->fd)); + return 0; + } + } + break; + case EPOLL_CTL_ADD: + if (errno == EEXIST) { + /* If an ADD operation fails with EEXIST, + * either the operation was redundant (as with a + * precautionary add), or we ran into a fun + * kernel bug where using dup*() to duplicate the + * same file into the same fd gives you the same epitem + * rather than a fresh one. For the second case, + * we must retry with MOD. */ + if (epoll_ctl(epollop->epfd, EPOLL_CTL_MOD, ch->fd, &epev) == -1) { + event_warn("Epoll ADD(%d) on %d retried as MOD; that failed too", + (int)epev.events, ch->fd); + return -1; + } else { + event_debug(("Epoll ADD(%d) on %d retried as MOD; succeeded.", + (int)epev.events, + ch->fd)); + return 0; + } + } + break; + case EPOLL_CTL_DEL: + if (errno == ENOENT || errno == EBADF || errno == EPERM) { + /* If a delete fails with one of these errors, + * that's fine too: we closed the fd before we + * got around to calling epoll_dispatch. */ + event_debug(("Epoll DEL(%d) on fd %d gave %s: DEL was unnecessary.", + (int)epev.events, + ch->fd, + strerror(errno))); + return 0; + } + break; + default: + break; + } + + event_warn("Epoll %s(%d) on fd %d failed. Old events were %d; read change was %d (%s); write change was %d (%s); close change was %d (%s)", + epoll_op_to_string(op), + (int)epev.events, + ch->fd, + ch->old_events, + ch->read_change, + change_to_string(ch->read_change), + ch->write_change, + change_to_string(ch->write_change), + ch->close_change, + change_to_string(ch->close_change)); + + return -1; +} + +static int +epoll_apply_changes(struct event_base *base) +{ + struct event_changelist *changelist = &base->changelist; + struct epollop *epollop = base->evbase; + struct event_change *ch; + + int r = 0; + int i; + + for (i = 0; i < changelist->n_changes; ++i) { + ch = &changelist->changes[i]; + if (epoll_apply_one_change(base, epollop, ch) < 0) + r = -1; + } + + return (r); +} + +static int +epoll_nochangelist_add(struct event_base *base, evutil_socket_t fd, + short old, short events, void *p) +{ + struct event_change ch; + ch.fd = fd; + ch.old_events = old; + ch.read_change = ch.write_change = ch.close_change = 0; + if (events & EV_WRITE) + ch.write_change = EV_CHANGE_ADD | + (events & EV_ET); + if (events & EV_READ) + ch.read_change = EV_CHANGE_ADD | + (events & EV_ET); + if (events & EV_CLOSED) + ch.close_change = EV_CHANGE_ADD | + (events & EV_ET); + + return epoll_apply_one_change(base, base->evbase, &ch); +} + +static int +epoll_nochangelist_del(struct event_base *base, evutil_socket_t fd, + short old, short events, void *p) +{ + struct event_change ch; + ch.fd = fd; + ch.old_events = old; + ch.read_change = ch.write_change = ch.close_change = 0; + if (events & EV_WRITE) + ch.write_change = EV_CHANGE_DEL; + if (events & EV_READ) + ch.read_change = EV_CHANGE_DEL; + if (events & EV_CLOSED) + ch.close_change = EV_CHANGE_DEL; + + return epoll_apply_one_change(base, base->evbase, &ch); +} + +static int +epoll_dispatch(struct event_base *base, struct timeval *tv) +{ + struct epollop *epollop = base->evbase; + struct epoll_event *events = epollop->events; + int i, res; + long timeout = -1; + +#ifdef USING_TIMERFD + if (epollop->timerfd >= 0) { + struct itimerspec is; + is.it_interval.tv_sec = 0; + is.it_interval.tv_nsec = 0; + if (tv == NULL) { + /* No timeout; disarm the timer. */ + is.it_value.tv_sec = 0; + is.it_value.tv_nsec = 0; + } else { + if (tv->tv_sec == 0 && tv->tv_usec == 0) { + /* we need to exit immediately; timerfd can't + * do that. */ + timeout = 0; + } + is.it_value.tv_sec = tv->tv_sec; + is.it_value.tv_nsec = tv->tv_usec * 1000; + } + /* TODO: we could avoid unnecessary syscalls here by only + calling timerfd_settime when the top timeout changes, or + when we're called with a different timeval. + */ + if (timerfd_settime(epollop->timerfd, 0, &is, NULL) < 0) { + event_warn("timerfd_settime"); + } + } else +#endif + if (tv != NULL) { + timeout = evutil_tv_to_msec_(tv); + if (timeout < 0 || timeout > MAX_EPOLL_TIMEOUT_MSEC) { + /* Linux kernels can wait forever if the timeout is + * too big; see comment on MAX_EPOLL_TIMEOUT_MSEC. */ + timeout = MAX_EPOLL_TIMEOUT_MSEC; + } + } + + epoll_apply_changes(base); + event_changelist_remove_all_(&base->changelist, base); + + EVBASE_RELEASE_LOCK(base, th_base_lock); + + res = epoll_wait(epollop->epfd, events, epollop->nevents, timeout); + + EVBASE_ACQUIRE_LOCK(base, th_base_lock); + + if (res == -1) { + if (errno != EINTR) { + event_warn("epoll_wait"); + return (-1); + } + + return (0); + } + + event_debug(("%s: epoll_wait reports %d", __func__, res)); + EVUTIL_ASSERT(res <= epollop->nevents); + + for (i = 0; i < res; i++) { + int what = events[i].events; + short ev = 0; +#ifdef USING_TIMERFD + if (events[i].data.fd == epollop->timerfd) + continue; +#endif + + if (what & (EPOLLHUP|EPOLLERR)) { + ev = EV_READ | EV_WRITE; + } else { + if (what & EPOLLIN) + ev |= EV_READ; + if (what & EPOLLOUT) + ev |= EV_WRITE; + 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 */ |