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NetBSD/lib/libevent/event.c

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/* $NetBSD: event.c,v 1.8 2007/01/26 19:34:30 cbiere Exp $ */
/* $OpenBSD: event.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
/*
* Copyright (c) 2000-2004 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Niels Provos.
* 4. 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 "config.h"
#endif
#include <sys/types.h>
#include <sys/tree.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <sys/_time.h>
#endif
#include <sys/queue.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
#include "event.h"
#include "event-internal.h"
#include "log.h"
#ifdef HAVE_SELECT
extern const struct eventop selectops;
#endif
#ifdef HAVE_POLL
extern const struct eventop pollops;
#endif
#ifdef HAVE_WORKING_KQUEUE
extern const struct eventop kqops;
#endif
/* In order of preference */
const struct eventop *eventops[] = {
#ifdef HAVE_WORKING_KQUEUE
&kqops,
#endif
#ifdef HAVE_POLL
&pollops,
#endif
#ifdef HAVE_SELECT
&selectops,
#endif
NULL
};
/* Global state */
struct event_list signalqueue;
struct event_base *current_base = NULL;
/* Handle signals - This is a deprecated interface */
int (*event_sigcb)(void); /* Signal callback when gotsig is set */
volatile int event_gotsig; /* Set in signal handler */
/* Prototypes */
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 int
compare(struct event *a, struct event *b)
{
if (timercmp(&a->ev_timeout, &b->ev_timeout, <))
return (-1);
else if (timercmp(&a->ev_timeout, &b->ev_timeout, >))
return (1);
if (a < b)
return (-1);
else if (a > b)
return (1);
return (0);
}
RB_PROTOTYPE(event_tree, event, ev_timeout_node, compare);
RB_GENERATE(event_tree, event, ev_timeout_node, compare);
void *
event_init(void)
{
int i;
if ((current_base = calloc(1, sizeof(struct event_base))) == NULL)
event_err(1, "%s: calloc");
event_sigcb = NULL;
event_gotsig = 0;
gettimeofday(&current_base->event_tv, NULL);
RB_INIT(&current_base->timetree);
TAILQ_INIT(&current_base->eventqueue);
TAILQ_INIT(&signalqueue);
current_base->evbase = NULL;
for (i = 0; eventops[i] && !current_base->evbase; i++) {
current_base->evsel = eventops[i];
current_base->evbase = current_base->evsel->init();
}
if (current_base->evbase == NULL)
event_errx(1, "%s: no event mechanism available", __func__);
if (getenv("EVENT_SHOW_METHOD"))
event_msgx("libevent using: %s\n",
current_base->evsel->name);
/* allocate a single active event queue */
event_base_priority_init(current_base, 1);
return (current_base);
}
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 (base->nactivequeues && npriorities != base->nactivequeues) {
for (i = 0; i < base->nactivequeues; ++i) {
free(base->activequeues[i]);
}
free(base->activequeues);
}
/* Allocate our priority queues */
base->nactivequeues = npriorities;
base->activequeues = (struct event_list **)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] = 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);
}
/*
* 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 *ev;
struct event_list *activeq = NULL;
int i;
short ncalls;
if (!base->event_count_active)
return;
for (i = 0; i < base->nactivequeues; ++i) {
if (TAILQ_FIRST(base->activequeues[i]) != NULL) {
activeq = base->activequeues[i];
break;
}
}
assert(activeq != NULL);
while ((ev = TAILQ_FIRST(activeq)) != NULL) {
event_queue_remove(base, ev, EVLIST_ACTIVE);
/* 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);
}
}
}
/*
* 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));
}
static void
event_loopexit_cb(int fd, short what, void *arg)
{
struct event_base *base = arg;
base->event_gotterm = 1;
}
/* not thread safe */
int
event_loopexit(struct timeval *tv)
{
return (event_once(-1, EV_TIMEOUT, event_loopexit_cb,
current_base, tv));
}
int
event_base_loopexit(struct event_base *event_base, struct timeval *tv)
{
return (event_once(-1, EV_TIMEOUT, event_loopexit_cb,
event_base, tv));
}
/* 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;
void *evbase = base->evbase;
struct timeval tv;
int res, done;
/* Calculate the initial events that we are waiting for */
if (evsel->recalc(base, evbase, 0) == -1)
return (-1);
done = 0;
while (!done) {
/* Terminate the loop if we have been asked to */
if (base->event_gotterm) {
base->event_gotterm = 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);
}
}
}
/* Check if time is running backwards */
gettimeofday(&tv, NULL);
if (timercmp(&tv, &base->event_tv, <)) {
struct timeval off;
event_debug(("%s: time is running backwards, corrected",
__func__));
timersub(&base->event_tv, &tv, &off);
timeout_correct(base, &off);
}
base->event_tv = tv;
if (!base->event_count_active && !(flags & EVLOOP_NONBLOCK))
timeout_next(base, &tv);
else
timerclear(&tv);
/* If we have no events, we just exit */
if (!event_haveevents(base)) {
event_debug(("%s: no events registered.", __func__));
return (1);
}
res = evsel->dispatch(base, evbase, &tv);
if (res == -1)
return (-1);
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;
if (evsel->recalc(base, evbase, 0) == -1)
return (-1);
}
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)(int, short, void *);
void *arg;
};
/* One-time callback, it deletes itself */
static void
event_once_cb(int fd, short events, void *arg)
{
struct event_once *eonce = arg;
(*eonce->cb)(fd, events, eonce->arg);
free(eonce);
}
/* Schedules an event once */
int
event_once(int fd, short events,
void (*callback)(int, short, void *), void *arg, struct timeval *tv)
{
struct event_once *eonce;
struct timeval etv;
/* We cannot support signals that just fire once */
if (events & EV_SIGNAL)
return (-1);
if ((eonce = calloc(1, sizeof(struct event_once))) == NULL)
return (-1);
eonce->cb = callback;
eonce->arg = arg;
if (events == EV_TIMEOUT) {
if (tv == NULL) {
timerclear(&etv);
tv = &etv;
}
evtimer_set(&eonce->ev, event_once_cb, eonce);
} else if (events & (EV_READ|EV_WRITE)) {
events &= EV_READ|EV_WRITE;
event_set(&eonce->ev, fd, events, event_once_cb, eonce);
} else {
/* Bad event combination */
free(eonce);
return (-1);
}
event_add(&eonce->ev, tv);
return (0);
}
void
event_set(struct event *ev, int fd, short events,
void (*callback)(int, 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_flags = EVLIST_INIT;
ev->ev_ncalls = 0;
ev->ev_pncalls = NULL;
/* by default, we put new events into the middle priority */
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;
return (0);
}
/*
* Set's the priority of an event - if an event is already scheduled
* changing the priority is going to fail.
*/
int
event_priority_set(struct event *ev, int pri)
{
if (ev->ev_flags & EVLIST_ACTIVE)
return (-1);
if (pri < 0 || pri >= ev->ev_base->nactivequeues)
return (-1);
ev->ev_pri = pri;
return (0);
}
/*
* Checks if a specific event is pending or scheduled.
*/
int
event_pending(struct event *ev, short event, struct timeval *tv)
{
int flags = 0;
if (ev->ev_flags & EVLIST_INSERTED)
flags |= (ev->ev_events & (EV_READ|EV_WRITE));
if (ev->ev_flags & EVLIST_ACTIVE)
flags |= ev->ev_res;
if (ev->ev_flags & EVLIST_TIMEOUT)
flags |= EV_TIMEOUT;
if (ev->ev_flags & EVLIST_SIGNAL)
flags |= EV_SIGNAL;
event &= (EV_TIMEOUT|EV_READ|EV_WRITE|EV_SIGNAL);
/* See if there is a timeout that we should report */
if (tv != NULL && (flags & event & EV_TIMEOUT))
*tv = ev->ev_timeout;
return (flags & event);
}
int
event_add(struct event *ev, struct timeval *tv)
{
struct event_base *base = ev->ev_base;
const struct eventop *evsel = base->evsel;
void *evbase = base->evbase;
event_debug((
"event_add: event: %p, %s%s%scall %p",
ev,
ev->ev_events & EV_READ ? "EV_READ " : " ",
ev->ev_events & EV_WRITE ? "EV_WRITE " : " ",
tv ? "EV_TIMEOUT " : " ",
ev->ev_callback));
assert(!(ev->ev_flags & ~EVLIST_ALL));
if (tv != NULL) {
struct timeval now;
if (ev->ev_flags & EVLIST_TIMEOUT)
event_queue_remove(base, ev, EVLIST_TIMEOUT);
/* Check if it is active due to a timeout. Rescheduling
* this timeout before the callback can be executed
* removes it from the active list. */
if ((ev->ev_flags & EVLIST_ACTIVE) &&
(ev->ev_res & EV_TIMEOUT)) {
/* See if we are just active executing this
* event in a loop
*/
if (ev->ev_ncalls && ev->ev_pncalls) {
/* Abort loop */
*ev->ev_pncalls = 0;
}
event_queue_remove(base, ev, EVLIST_ACTIVE);
}
gettimeofday(&now, NULL);
timeradd(&now, tv, &ev->ev_timeout);
event_debug((
"event_add: timeout in %d seconds, call %p",
tv->tv_sec, ev->ev_callback));
event_queue_insert(base, ev, EVLIST_TIMEOUT);
}
if ((ev->ev_events & (EV_READ|EV_WRITE)) &&
!(ev->ev_flags & (EVLIST_INSERTED|EVLIST_ACTIVE))) {
event_queue_insert(base, ev, EVLIST_INSERTED);
return (evsel->add(evbase, ev));
} else if ((ev->ev_events & EV_SIGNAL) &&
!(ev->ev_flags & EVLIST_SIGNAL)) {
event_queue_insert(base, ev, EVLIST_SIGNAL);
return (evsel->add(evbase, ev));
}
return (0);
}
int
event_del(struct event *ev)
{
struct event_base *base;
const struct eventop *evsel;
void *evbase;
event_debug(("event_del: %p, callback %p",
ev, ev->ev_callback));
/* An event without a base has not been added */
if (ev->ev_base == NULL)
return (-1);
base = ev->ev_base;
evsel = base->evsel;
evbase = base->evbase;
assert(!(ev->ev_flags & ~EVLIST_ALL));
/* See if we are just active executing this event in a loop */
if (ev->ev_ncalls && ev->ev_pncalls) {
/* Abort loop */
*ev->ev_pncalls = 0;
}
if (ev->ev_flags & EVLIST_TIMEOUT)
event_queue_remove(base, ev, EVLIST_TIMEOUT);
if (ev->ev_flags & EVLIST_ACTIVE)
event_queue_remove(base, ev, EVLIST_ACTIVE);
if (ev->ev_flags & EVLIST_INSERTED) {
event_queue_remove(base, ev, EVLIST_INSERTED);
return (evsel->del(evbase, ev));
} else if (ev->ev_flags & EVLIST_SIGNAL) {
event_queue_remove(base, ev, EVLIST_SIGNAL);
return (evsel->del(evbase, ev));
}
return (0);
}
void
event_active(struct event *ev, int res, short ncalls)
{
/* We get different kinds of events, add them together */
if (ev->ev_flags & EVLIST_ACTIVE) {
ev->ev_res |= res;
return;
}
ev->ev_res = res;
ev->ev_ncalls = ncalls;
ev->ev_pncalls = NULL;
event_queue_insert(ev->ev_base, ev, EVLIST_ACTIVE);
}
int
timeout_next(struct event_base *base, struct timeval *tv)
{
struct timeval dflt = TIMEOUT_DEFAULT;
struct timeval now;
struct event *ev;
if ((ev = RB_MIN(event_tree, &base->timetree)) == NULL) {
*tv = dflt;
return (0);
}
if (gettimeofday(&now, NULL) == -1)
return (-1);
if (timercmp(&ev->ev_timeout, &now, <=)) {
timerclear(tv);
return (0);
}
timersub(&ev->ev_timeout, &now, tv);
assert(tv->tv_sec >= 0);
assert(tv->tv_usec >= 0);
event_debug(("timeout_next: in %d seconds", tv->tv_sec));
return (0);
}
static void
timeout_correct(struct event_base *base, struct timeval *off)
{
struct event *ev;
/*
* We can modify the key element of the node without destroying
* the key, beause we apply it to all in the right order.
*/
RB_FOREACH(ev, event_tree, &base->timetree)
timersub(&ev->ev_timeout, off, &ev->ev_timeout);
}
void
timeout_process(struct event_base *base)
{
struct timeval now;
struct event *ev, *next;
gettimeofday(&now, NULL);
for (ev = RB_MIN(event_tree, &base->timetree); ev; ev = next) {
if (timercmp(&ev->ev_timeout, &now, >))
break;
next = RB_NEXT(event_tree, &base->timetree, ev);
event_queue_remove(base, ev, EVLIST_TIMEOUT);
/* delete this event from the I/O queues */
event_del(ev);
event_debug(("timeout_process: call %p",
ev->ev_callback));
event_active(ev, EV_TIMEOUT, 1);
}
}
void
event_queue_remove(struct event_base *base, struct event *ev, int queue)
{
int docount = 1;
if (!(ev->ev_flags & queue))
event_errx(1, "%s: %p(fd %d) not on queue %x", __func__,
ev, ev->ev_fd, queue);
if (ev->ev_flags & EVLIST_INTERNAL)
docount = 0;
if (docount)
base->event_count--;
ev->ev_flags &= ~queue;
switch (queue) {
case EVLIST_ACTIVE:
if (docount)
base->event_count_active--;
TAILQ_REMOVE(base->activequeues[ev->ev_pri],
ev, ev_active_next);
break;
case EVLIST_SIGNAL:
TAILQ_REMOVE(&signalqueue, ev, ev_signal_next);
break;
case EVLIST_TIMEOUT:
RB_REMOVE(event_tree, &base->timetree, ev);
break;
case EVLIST_INSERTED:
TAILQ_REMOVE(&base->eventqueue, ev, ev_next);
break;
default:
event_errx(1, "%s: unknown queue %x", __func__, queue);
}
}
void
event_queue_insert(struct event_base *base, struct event *ev, int queue)
{
int docount = 1;
if (ev->ev_flags & queue) {
/* Double insertion is possible for active events */
if (queue & EVLIST_ACTIVE)
return;
event_errx(1, "%s: %p(fd %d) already on queue %x", __func__,
ev, ev->ev_fd, queue);
}
if (ev->ev_flags & EVLIST_INTERNAL)
docount = 0;
if (docount)
base->event_count++;
ev->ev_flags |= queue;
switch (queue) {
case EVLIST_ACTIVE:
if (docount)
base->event_count_active++;
TAILQ_INSERT_TAIL(base->activequeues[ev->ev_pri],
ev,ev_active_next);
break;
case EVLIST_SIGNAL:
TAILQ_INSERT_TAIL(&signalqueue, ev, ev_signal_next);
break;
case EVLIST_TIMEOUT: {
struct event *tmp = RB_INSERT(event_tree, &base->timetree, ev);
(void)tmp;
assert(tmp == NULL);
break;
}
case EVLIST_INSERTED:
TAILQ_INSERT_TAIL(&base->eventqueue, ev, ev_next);
break;
default:
event_errx(1, "%s: unknown queue %x", __func__, queue);
}
}
/* Functions for debugging */
const char *
event_get_version(void)
{
return (VERSION);
}
/*
* No thread-safe interface needed - the information should be the same
* for all threads.
*/
const char *
event_get_method(void)
{
return (current_base->evsel->name);
}
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