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event.c
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/*
* Copyright (c) 2000-2007 Niels Provos <[email protected]>
* Copyright (c) 2007-2009 Niels Provos and 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.
*/
#ifdef HAVE_CONFIG_H
#include "event-config.h"
#endif
#ifdef WIN32
#include <winsock2.h>
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#endif
#include <sys/types.h>
#ifndef WIN32
#ifdef _EVENT_HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <sys/_time.h>
#endif
#endif
#include <sys/queue.h>
#ifdef _EVENT_HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#ifdef _EVENT_HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef _EVENT_HAVE_SYS_EVENTFD_H
#include <sys/eventfd.h>
#endif
#include <ctype.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <assert.h>
#include <time.h>
#include "event2/event.h"
#include "event2/event_struct.h"
#include "event2/event_compat.h"
#include "event-internal.h"
#include "defer-internal.h"
#include "evthread-internal.h"
#include "event2/thread.h"
#include "event2/util.h"
#include "log-internal.h"
#include "evmap-internal.h"
#ifdef _EVENT_HAVE_EVENT_PORTS
extern const struct eventop evportops;
#endif
#ifdef _EVENT_HAVE_SELECT
extern const struct eventop selectops;
#endif
#ifdef _EVENT_HAVE_POLL
extern const struct eventop pollops;
#endif
#ifdef _EVENT_HAVE_EPOLL
extern const struct eventop epollops;
#endif
#ifdef _EVENT_HAVE_WORKING_KQUEUE
extern const struct eventop kqops;
#endif
#ifdef _EVENT_HAVE_DEVPOLL
extern const struct eventop devpollops;
#endif
#ifdef WIN32
extern const struct eventop win32ops;
#endif
/* In order of preference */
static const struct eventop *eventops[] = {
#ifdef _EVENT_HAVE_EVENT_PORTS
&evportops,
#endif
#ifdef _EVENT_HAVE_WORKING_KQUEUE
&kqops,
#endif
#ifdef _EVENT_HAVE_EPOLL
&epollops,
#endif
#ifdef _EVENT_HAVE_DEVPOLL
&devpollops,
#endif
#ifdef _EVENT_HAVE_POLL
&pollops,
#endif
#ifdef _EVENT_HAVE_SELECT
&selectops,
#endif
#ifdef WIN32
&win32ops,
#endif
NULL
};
/* Global state */
struct event_base *current_base = NULL;
extern struct event_base *evsig_base;
static int use_monotonic;
/* Handle signals - This is a deprecated interface */
int (*event_sigcb)(void); /* Signal callback when gotsig is set */
volatile sig_atomic_t event_gotsig; /* Set in signal handler */
/* Prototypes */
static inline int event_add_internal(struct event *ev,
const struct timeval *tv);
static inline int event_del_internal(struct event *ev);
static inline void event_active_internal(struct event *ev, int res,short count);
static void event_queue_insert(struct event_base *, struct event *, int);
static void event_queue_remove(struct event_base *, struct event *, int);
static int event_haveevents(struct event_base *);
static void event_process_active(struct event_base *);
static int timeout_next(struct event_base *, struct timeval **);
static void timeout_process(struct event_base *);
static void timeout_correct(struct event_base *, struct timeval *);
static void event_signal_closure(struct event_base *, struct event *ev);
static void event_persist_closure(struct event_base *, struct event *ev);
static int evthread_notify_base(struct event_base *base);
static void
detect_monotonic(void)
{
#if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
use_monotonic = 1;
#endif
}
static int
gettime(struct event_base *base, struct timeval *tp)
{
if (base->tv_cache.tv_sec) {
*tp = base->tv_cache;
return (0);
}
#if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
if (use_monotonic) {
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
return (-1);
tp->tv_sec = ts.tv_sec;
tp->tv_usec = ts.tv_nsec / 1000;
return (0);
}
#endif
return (evutil_gettimeofday(tp, NULL));
}
struct event_base *
event_init(void)
{
struct event_base *base = event_base_new();
if (base != NULL)
current_base = base;
return (base);
}
struct event_base *
event_base_new(void)
{
return (event_base_new_with_config(NULL));
}
static int
event_config_is_avoided_method(struct event_config *cfg, const char *method)
{
struct event_config_entry *entry;
TAILQ_FOREACH(entry, &cfg->entries, next) {
if (entry->avoid_method != NULL &&
strcmp(entry->avoid_method, method) == 0)
return (1);
}
return (0);
}
static int
event_is_method_disabled(const char *name)
{
char environment[64];
int i;
evutil_snprintf(environment, sizeof(environment), "EVENT_NO%s", name);
for (i = 8; environment[i] != '\0'; ++i)
environment[i] = toupper(environment[i]);
return (getenv(environment) != NULL);
}
enum event_method_feature
event_base_get_features(struct event_base *base)
{
return base->evsel->features;
}
struct event_base *
event_base_new_with_config(struct event_config *cfg)
{
int i;
struct event_base *base;
if ((base = mm_calloc(1, sizeof(struct event_base))) == NULL)
event_err(1, "%s: calloc", __func__);
event_sigcb = NULL;
event_gotsig = 0;
detect_monotonic();
gettime(base, &base->event_tv);
min_heap_ctor(&base->timeheap);
TAILQ_INIT(&base->eventqueue);
TAILQ_INIT(&base->deferred_cb_list);
base->sig.ev_signal_pair[0] = -1;
base->sig.ev_signal_pair[1] = -1;
evmap_io_initmap(&base->io);
evmap_signal_initmap(&base->sigmap);
base->evbase = NULL;
for (i = 0; eventops[i] && !base->evbase; i++) {
if (cfg != NULL) {
/* determine if this backend should be avoided */
if (event_config_is_avoided_method(cfg,
eventops[i]->name))
continue;
if ((eventops[i]->features & cfg->require_features)
!= cfg->require_features)
continue;
}
/* also obey the environment variables */
if (event_is_method_disabled(eventops[i]->name))
continue;
base->evsel = eventops[i];
base->evbase = base->evsel->init(base);
}
if (base->evbase == NULL) {
if (cfg == NULL)
event_errx(1, "%s: no event mechanism available",
__func__);
else {
event_base_free(base);
return NULL;
}
}
if (getenv("EVENT_SHOW_METHOD"))
event_msgx("libevent using: %s", base->evsel->name);
/* allocate a single active event queue */
event_base_priority_init(base, 1);
/* prepare for threading */
base->th_notify_fd[0] = -1;
base->th_notify_fd[1] = -1;
if (!cfg || !(cfg->flags & EVENT_BASE_FLAG_NOLOCK)) {
int r;
EVTHREAD_ALLOC_LOCK(base->th_base_lock);
r = evthread_make_base_notifiable(base);
if (r<0) {
event_base_free(base);
return NULL;
}
}
return (base);
}
void
event_base_free(struct event_base *base)
{
int i, n_deleted=0;
struct event *ev;
if (base == NULL && current_base)
base = current_base;
if (base == current_base)
current_base = NULL;
/* XXX(niels) - check for internal events first */
assert(base);
/* threading fds if we have them */
if (base->th_notify_fd[0] != -1) {
event_del(&base->th_notify);
EVUTIL_CLOSESOCKET(base->th_notify_fd[0]);
EVUTIL_CLOSESOCKET(base->th_notify_fd[1]);
base->th_notify_fd[0] = -1;
base->th_notify_fd[1] = -1;
}
EVTHREAD_FREE_LOCK(base->th_base_lock);
/* Delete all non-internal events. */
for (ev = TAILQ_FIRST(&base->eventqueue); ev; ) {
struct event *next = TAILQ_NEXT(ev, ev_next);
if (!(ev->ev_flags & EVLIST_INTERNAL)) {
event_del(ev);
++n_deleted;
}
ev = next;
}
while ((ev = min_heap_top(&base->timeheap)) != NULL) {
event_del(ev);
++n_deleted;
}
for (i = 0; i < base->nactivequeues; ++i) {
for (ev = TAILQ_FIRST(base->activequeues[i]); ev; ) {
struct event *next = TAILQ_NEXT(ev, ev_active_next);
if (!(ev->ev_flags & EVLIST_INTERNAL)) {
event_del(ev);
++n_deleted;
}
ev = next;
}
}
if (n_deleted)
event_debug(("%s: %d events were still set in base",
__func__, n_deleted));
if (base->evsel != NULL && base->evsel->dealloc != NULL)
base->evsel->dealloc(base);
for (i = 0; i < base->nactivequeues; ++i)
assert(TAILQ_EMPTY(base->activequeues[i]));
assert(min_heap_empty(&base->timeheap));
min_heap_dtor(&base->timeheap);
for (i = 0; i < base->nactivequeues; ++i)
mm_free(base->activequeues[i]);
mm_free(base->activequeues);
assert(TAILQ_EMPTY(&base->eventqueue));
evmap_io_clear(&base->io);
evmap_signal_clear(&base->sigmap);
mm_free(base);
}
/* reinitialized the event base after a fork */
int
event_reinit(struct event_base *base)
{
const struct eventop *evsel = base->evsel;
int res = 0;
struct event *ev;
/* check if this event mechanism requires reinit */
if (!evsel->need_reinit)
return (0);
/* prevent internal delete */
if (base->sig.ev_signal_added) {
/* we cannot call event_del here because the base has
* not been reinitialized yet. */
event_queue_remove(base, &base->sig.ev_signal,
EVLIST_INSERTED);
if (base->sig.ev_signal.ev_flags & EVLIST_ACTIVE)
event_queue_remove(base, &base->sig.ev_signal,
EVLIST_ACTIVE);
base->sig.ev_signal_added = 0;
}
if (base->evsel->dealloc != NULL)
base->evsel->dealloc(base);
base->evbase = evsel->init(base);
if (base->evbase == NULL)
event_errx(1, "%s: could not reinitialize event mechanism",
__func__);
evmap_io_clear(&base->io);
evmap_signal_clear(&base->sigmap);
TAILQ_FOREACH(ev, &base->eventqueue, ev_next) {
if (ev->ev_events & (EV_READ|EV_WRITE)) {
if (evmap_io_add(base, ev->ev_fd, ev) == -1)
res = -1;
} else if (ev->ev_events & EV_SIGNAL) {
if (evmap_signal_add(base, ev->ev_fd, ev) == -1)
res = -1;
}
}
return (res);
}
const char **
event_get_supported_methods(void)
{
static const char **methods;
const struct eventop **method;
const char **tmp;
int i = 0, k;
/* count all methods */
for (method = &eventops[0]; *method != NULL; ++method) {
if (event_is_method_disabled((*method)->name))
continue;
++i;
}
/* allocate one more than we need for the NULL pointer */
tmp = mm_malloc((i + 1) * sizeof(char *));
if (tmp == NULL)
return (NULL);
/* populate the array with the supported methods */
for (k = 0, i = 0; eventops[k] != NULL; ++k) {
if (event_is_method_disabled(eventops[k]->name))
continue;
tmp[i++] = eventops[k]->name;
}
tmp[i] = NULL;
if (methods != NULL)
mm_free(methods);
methods = tmp;
return (methods);
}
struct event_config *
event_config_new(void)
{
struct event_config *cfg = mm_malloc(sizeof(*cfg));
if (cfg == NULL)
return (NULL);
TAILQ_INIT(&cfg->entries);
cfg->require_features = 0;
return (cfg);
}
static void
event_config_entry_free(struct event_config_entry *entry)
{
if (entry->avoid_method != NULL)
mm_free((char *)entry->avoid_method);
mm_free(entry);
}
void
event_config_free(struct event_config *cfg)
{
struct event_config_entry *entry;
while ((entry = TAILQ_FIRST(&cfg->entries)) != NULL) {
TAILQ_REMOVE(&cfg->entries, entry, next);
event_config_entry_free(entry);
}
mm_free(cfg);
}
int
event_config_avoid_method(struct event_config *cfg, const char *method)
{
struct event_config_entry *entry = mm_malloc(sizeof(*entry));
if (entry == NULL)
return (-1);
if ((entry->avoid_method = mm_strdup(method)) == NULL) {
mm_free(entry);
return (-1);
}
TAILQ_INSERT_TAIL(&cfg->entries, entry, next);
return (0);
}
int
event_config_require_features(struct event_config *cfg,
enum event_method_feature features)
{
if (!cfg)
return (-1);
cfg->require_features = features;
return (0);
}
int
event_priority_init(int npriorities)
{
return event_base_priority_init(current_base, npriorities);
}
int
event_base_priority_init(struct event_base *base, int npriorities)
{
int i;
if (base->event_count_active)
return (-1);
if (npriorities == base->nactivequeues)
return (0);
if (base->nactivequeues) {
for (i = 0; i < base->nactivequeues; ++i) {
mm_free(base->activequeues[i]);
}
mm_free(base->activequeues);
}
/* Allocate our priority queues */
base->nactivequeues = npriorities;
base->activequeues = (struct event_list **)mm_calloc(
base->nactivequeues,
npriorities * sizeof(struct event_list *));
if (base->activequeues == NULL)
event_err(1, "%s: calloc", __func__);
for (i = 0; i < base->nactivequeues; ++i) {
base->activequeues[i] = mm_malloc(sizeof(struct event_list));
if (base->activequeues[i] == NULL)
event_err(1, "%s: malloc", __func__);
TAILQ_INIT(base->activequeues[i]);
}
return (0);
}
int
event_haveevents(struct event_base *base)
{
return (base->event_count > 0);
}
static void
event_persist_closure(struct event_base *base, struct event *ev)
{
/* reschedule the persistent event if we have a timeout */
if (ev->ev_io_timeout.tv_sec || ev->ev_io_timeout.tv_usec)
event_add(ev, &ev->ev_io_timeout);
(*ev->ev_callback)((int)ev->ev_fd, ev->ev_res, ev->ev_arg);
}
static void
event_signal_closure(struct event_base *base, struct event *ev)
{
short ncalls;
/* Allows deletes to work */
ncalls = ev->ev_ncalls;
ev->ev_pncalls = &ncalls;
while (ncalls) {
ncalls--;
ev->ev_ncalls = ncalls;
(*ev->ev_callback)((int)ev->ev_fd, ev->ev_res, ev->ev_arg);
if (event_gotsig || base->event_break)
return;
}
}
/*
Helper for event_process_active to process all the events in a single queue,
releasing the lock as we go. This function requires that the lock be held
when it's invoked. Returns -1 if we get a signal or an event_break that
means we should stop processing any active events now. Otherwise returns
the number of non-internal events that we processed.
*/
static int
event_process_active_single_queue(struct event_base *base,
struct event_list *activeq)
{
struct event *ev;
int count = 0;
assert(activeq != NULL);
for (ev = TAILQ_FIRST(activeq); ev; ev = TAILQ_FIRST(activeq)) {
if (ev->ev_events & EV_PERSIST)
event_queue_remove(base, ev, EVLIST_ACTIVE);
else
event_del_internal(ev);
if (!(ev->ev_flags & EVLIST_INTERNAL))
++count;
event_debug((
"event_process_active: event: %p, %s%scall %p",
ev,
ev->ev_res & EV_READ ? "EV_READ " : " ",
ev->ev_res & EV_WRITE ? "EV_WRITE " : " ",
ev->ev_callback));
EVBASE_RELEASE_LOCK(base,
EVTHREAD_WRITE, th_base_lock);
if (ev->ev_closure != NULL)
(*ev->ev_closure)(base, ev);
else
(*ev->ev_callback)(
(int)ev->ev_fd, ev->ev_res, ev->ev_arg);
if (event_gotsig || base->event_break)
return -1;
EVBASE_ACQUIRE_LOCK(base, EVTHREAD_WRITE, th_base_lock);
}
return count;
}
static int
event_process_deferred_callbacks(struct event_base *base)
{
int count = 0;
struct deferred_cb *cb;
while ((cb = TAILQ_FIRST(&base->deferred_cb_list))) {
cb->queued = 0;
TAILQ_REMOVE(&base->deferred_cb_list, cb, cb_next);
--base->event_count_active;
EVBASE_RELEASE_LOCK(base, EVTHREAD_WRITE, th_base_lock);
cb->cb(cb, cb->arg);
++count;
if (event_gotsig || base->event_break)
return -1;
EVBASE_ACQUIRE_LOCK(base, EVTHREAD_WRITE, th_base_lock);
}
return count;
}
/*
* Active events are stored in priority queues. Lower priorities are always
* process before higher priorities. Low priority events can starve high
* priority ones.
*/
static void
event_process_active(struct event_base *base)
{
struct event_list *activeq = NULL;
int i, c;
EVBASE_ACQUIRE_LOCK(base, EVTHREAD_WRITE, th_base_lock);
for (i = 0; i < base->nactivequeues; ++i) {
if (TAILQ_FIRST(base->activequeues[i]) != NULL) {
activeq = base->activequeues[i];
c = event_process_active_single_queue(base, activeq);
if (c < 0)
return; /* already unlocked */
else if (c > 0)
break; /* Processed a real event; do not
* consider lower-priority events */
/* If we get here, all of the events we processed
* were internal. Continue. */
}
}
event_process_deferred_callbacks(base);
EVBASE_RELEASE_LOCK(base, EVTHREAD_WRITE, th_base_lock);
}
/*
* Wait continously for events. We exit only if no events are left.
*/
int
event_dispatch(void)
{
return (event_loop(0));
}
int
event_base_dispatch(struct event_base *event_base)
{
return (event_base_loop(event_base, 0));
}
const char *
event_base_get_method(struct event_base *base)
{
assert(base);
return (base->evsel->name);
}
static void
event_loopexit_cb(evutil_socket_t fd, short what, void *arg)
{
struct event_base *base = arg;
base->event_gotterm = 1;
}
/* not thread safe */
int
event_loopexit(const struct timeval *tv)
{
return (event_once(-1, EV_TIMEOUT, event_loopexit_cb,
current_base, tv));
}
int
event_base_loopexit(struct event_base *event_base, const struct timeval *tv)
{
return (event_base_once(event_base, -1, EV_TIMEOUT, event_loopexit_cb,
event_base, tv));
}
int
event_loopbreak(void)
{
return (event_base_loopbreak(current_base));
}
int
event_base_loopbreak(struct event_base *event_base)
{
if (event_base == NULL)
return (-1);
EVBASE_ACQUIRE_LOCK(event_base, EVTHREAD_WRITE, th_base_lock);
event_base->event_break = 1;
EVBASE_RELEASE_LOCK(event_base, EVTHREAD_WRITE, th_base_lock);
if (!EVBASE_IN_THREAD(event_base)) {
return evthread_notify_base(event_base);
} else {
return (0);
}
}
/* not thread safe */
int
event_loop(int flags)
{
return event_base_loop(current_base, flags);
}
int
event_base_loop(struct event_base *base, int flags)
{
const struct eventop *evsel = base->evsel;
struct timeval tv;
struct timeval *tv_p;
int res, done;
/* clear time cache */
base->tv_cache.tv_sec = 0;
if (base->sig.ev_signal_added)
evsig_base = base;
done = 0;
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
base->th_owner_id = EVTHREAD_GET_ID();
#endif
while (!done) {
/* Terminate the loop if we have been asked to */
if (base->event_gotterm) {
base->event_gotterm = 0;
break;
}
if (base->event_break) {
base->event_break = 0;
break;
}
/* You cannot use this interface for multi-threaded apps */
while (event_gotsig) {
event_gotsig = 0;
if (event_sigcb) {
res = (*event_sigcb)();
if (res == -1) {
errno = EINTR;
return (-1);
}
}
}
timeout_correct(base, &tv);
tv_p = &tv;
if (!base->event_count_active && !(flags & EVLOOP_NONBLOCK)) {
timeout_next(base, &tv_p);
} else {
/*
* if we have active events, we just poll new events
* without waiting.
*/
evutil_timerclear(&tv);
}
/* If we have no events, we just exit */
if (!event_haveevents(base) && !base->event_count_active) {
event_debug(("%s: no events registered.", __func__));
return (1);
}
/* update last old time */
gettime(base, &base->event_tv);
/* clear time cache */
base->tv_cache.tv_sec = 0;
res = evsel->dispatch(base, tv_p);
if (res == -1)
return (-1);
gettime(base, &base->tv_cache);
timeout_process(base);
if (base->event_count_active) {
event_process_active(base);
if (!base->event_count_active && (flags & EVLOOP_ONCE))
done = 1;
} else if (flags & EVLOOP_NONBLOCK)
done = 1;
}
/* clear time cache */
base->tv_cache.tv_sec = 0;
event_debug(("%s: asked to terminate loop.", __func__));
return (0);
}
/* Sets up an event for processing once */
struct event_once {
struct event ev;
void (*cb)(evutil_socket_t, short, void *);
void *arg;
};
/* One-time callback, it deletes itself */
static void
event_once_cb(evutil_socket_t fd, short events, void *arg)
{
struct event_once *eonce = arg;
(*eonce->cb)(fd, events, eonce->arg);
mm_free(eonce);
}
/* not threadsafe, event scheduled once. */
int
event_once(evutil_socket_t fd, short events,
void (*callback)(evutil_socket_t, short, void *),
void *arg, const struct timeval *tv)
{
return event_base_once(current_base, fd, events, callback, arg, tv);
}
/* Schedules an event once */
int
event_base_once(struct event_base *base, evutil_socket_t fd, short events,
void (*callback)(evutil_socket_t, short, void *),
void *arg, const struct timeval *tv)
{
struct event_once *eonce;
struct timeval etv;
int res = 0;
/* We cannot support signals that just fire once */
if (events & EV_SIGNAL)
return (-1);
if ((eonce = mm_calloc(1, sizeof(struct event_once))) == NULL)
return (-1);
eonce->cb = callback;
eonce->arg = arg;
if (events == EV_TIMEOUT) {
if (tv == NULL) {
evutil_timerclear(&etv);
tv = &etv;
}
evtimer_assign(&eonce->ev, base, event_once_cb, eonce);
} else if (events & (EV_READ|EV_WRITE)) {
events &= EV_READ|EV_WRITE;
event_assign(&eonce->ev, base, fd, events, event_once_cb, eonce);
} else {
/* Bad event combination */
mm_free(eonce);
return (-1);
}
if (res == 0)
res = event_add(&eonce->ev, tv);
if (res != 0) {
mm_free(eonce);
return (res);
}
return (0);
}
void
event_set(struct event *ev, evutil_socket_t fd, short events,
void (*callback)(evutil_socket_t, short, void *), void *arg)
{
/* Take the current base - caller needs to set the real base later */
ev->ev_base = current_base;
ev->ev_callback = callback;
ev->ev_arg = arg;
ev->ev_fd = fd;
ev->ev_events = events;
ev->ev_res = 0;
ev->ev_flags = EVLIST_INIT;
ev->ev_ncalls = 0;
ev->ev_pncalls = NULL;
if (events & EV_SIGNAL) {
if ((events & (EV_READ|EV_WRITE)) != 0)
event_errx(1, "%s: EV_SIGNAL incompatible use",
__func__);
ev->ev_closure = event_signal_closure;
} else {
if (events & EV_PERSIST) {
timerclear(&ev->ev_io_timeout);
ev->ev_closure = event_persist_closure;
} else {
ev->ev_closure = NULL;
}
}
min_heap_elem_init(ev);
/* by default, we put new events into the middle priority */
if (current_base)
ev->ev_pri = current_base->nactivequeues/2;
}
int
event_base_set(struct event_base *base, struct event *ev)
{
/* Only innocent events may be assigned to a different base */
if (ev->ev_flags != EVLIST_INIT)
return (-1);
ev->ev_base = base;
ev->ev_pri = base->nactivequeues/2;