event.c

/*
 * 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. 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

#ifdef WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#endif
#include <sys/types.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>
#ifndef WIN32
#include <unistd.h>
#endif
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <assert.h>
#include <time.h>

#include "event.h"
#include "event-internal.h"
#include "evutil.h"
#include "log.h"

#ifdef HAVE_EVENT_PORTS
extern const struct eventop evportops;
#endif
#ifdef HAVE_SELECT
extern const struct eventop selectops;
#endif
#ifdef HAVE_POLL
extern const struct eventop pollops;
#endif
#ifdef HAVE_EPOLL
extern const struct eventop epollops;
#endif
#ifdef HAVE_WORKING_KQUEUE
extern const struct eventop kqops;
#endif
#ifdef 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 HAVE_EVENT_PORTS
        &evportops,
#endif
#ifdef HAVE_WORKING_KQUEUE
        &kqops,
#endif
#ifdef HAVE_EPOLL
        &epollops,
#endif
#ifdef HAVE_DEVPOLL
        &devpollops,
#endif
#ifdef HAVE_POLL
        &pollops,
#endif
#ifdef HAVE_SELECT
        &selectops,
#endif
#ifdef WIN32
        &win32ops,
#endif
        NULL
};

/* Global state */
struct event_base *current_base = NULL;
extern struct event_base *evsignal_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 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
detect_monotonic(void)
{
#if defined(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(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)
{
        int i;
        struct event_base *base;

        if ((base = 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);
        base->sig.ev_signal_pair[0] = -1;
        base->sig.ev_signal_pair[1] = -1;
        
        base->evbase = NULL;
        for (i = 0; eventops[i] && !base->evbase; i++) {
                base->evsel = eventops[i];

                base->evbase = base->evsel->init(base);
        }

        if (base->evbase == NULL)
                event_errx(1, "%s: no event mechanism available", __func__);

        if (getenv("EVENT_SHOW_METHOD")) 
                event_msgx("libevent using: %s\n",
                           base->evsel->name);

        /* allocate a single active event queue */
        event_base_priority_init(base, 1);

        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);
        /* 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->dealloc != NULL)
                base->evsel->dealloc(base, base->evbase);

        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)
                free(base->activequeues[i]);
        free(base->activequeues);

        assert(TAILQ_EMPTY(&base->eventqueue));

        free(base);
}

/* reinitialized the event base after a fork */
int
event_reinit(struct event_base *base)
{
        const struct eventop *evsel = base->evsel;
        void *evbase = base->evbase;
        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);
        evbase = base->evbase = evsel->init(base);
        if (base->evbase == NULL)
                event_errx(1, "%s: could not reinitialize event mechanism",
                    __func__);

        TAILQ_FOREACH(ev, &base->eventqueue, ev_next) {
                if (evsel->add(evbase, ev) == -1)
                        res = -1;
        }

        return (res);
}

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;

        for (i = 0; i < base->nactivequeues; ++i) {
                if (TAILQ_FIRST(base->activequeues[i]) != NULL) {
                        activeq = base->activequeues[i];
                        break;
                }
        }

        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(ev);
                
                /* 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;
                }
        }
}

/*
 * 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(int 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));
}

/* not thread safe */
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);

        event_base->event_break = 1;
        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;
        void *evbase = base->evbase;
        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)
                evsignal_base = base;
        done = 0;
        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)) {
                        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, evbase, 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)(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);
}

/* not threadsafe, event scheduled once. */
int
event_once(int fd, short events,
    void (*callback)(int, 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, int fd, short events,
    void (*callback)(int, short, void *), void *arg, const struct timeval *tv)
{
        struct event_once *eonce;
        struct timeval etv;
        int res;

        /* 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) {
                        evutil_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);
        }

        res = event_base_set(base, &eonce->ev);
        if (res == 0)
                res = event_add(&eonce->ev, tv);
        if (res != 0) {
                free(eonce);
                return (res);
        }

        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_res = 0;
        ev->ev_flags = EVLIST_INIT;
        ev->ev_ncalls = 0;
        ev->ev_pncalls = 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;

        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)
{
        struct timeval  now, res;
        int flags = 0;

        if (ev->ev_flags & EVLIST_INSERTED)
                flags |= (ev->ev_events & (EV_READ|EV_WRITE|EV_SIGNAL));
        if (ev->ev_flags & EVLIST_ACTIVE)
                flags |= ev->ev_res;
        if (ev->ev_flags & EVLIST_TIMEOUT)
                flags |= EV_TIMEOUT;

        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)) {
                gettime(ev->ev_base, &now);
                evutil_timersub(&ev->ev_timeout, &now, &res);
                /* correctly remap to real time */
                evutil_gettimeofday(&now, NULL);
                evutil_timeradd(&now, &res, tv);
        }

        return (flags & event);
}

int
event_add(struct event *ev, const struct timeval *tv)
{
        struct event_base *base = ev->ev_base;
        const struct eventop *evsel = base->evsel;
        void *evbase = base->evbase;
        int res = 0;

        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));

        /*
         * prepare for timeout insertion further below, if we get a
         * failure on any step, we should not change any state.
         */
        if (tv != NULL && !(ev->ev_flags & EVLIST_TIMEOUT)) {
                if (min_heap_reserve(&base->timeheap,
                        1 + min_heap_size(&base->timeheap)) == -1)
                        return (-1);  /* ENOMEM == errno */
        }

        if ((ev->ev_events & (EV_READ|EV_WRITE|EV_SIGNAL)) &&
            !(ev->ev_flags & (EVLIST_INSERTED|EVLIST_ACTIVE))) {
                res = evsel->add(evbase, ev);
                if (res != -1)
                        event_queue_insert(base, ev, EVLIST_INSERTED);
        }

        /* 
         * we should change the timout state only if the previous event
         * addition succeeded.
         */
        if (res != -1 && tv != NULL) {
                struct timeval now;

                /* 
                 * we already reserved memory above for the case where we
                 * are not replacing an exisiting timeout.
                 */
                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);
                }

                gettime(base, &now);
                evutil_timeradd(&now, tv, &ev->ev_timeout);

                event_debug((
                         "event_add: timeout in %ld seconds, call %p",
                         tv->tv_sec, ev->ev_callback));

                event_queue_insert(base, ev, EVLIST_TIMEOUT);
        }

        return (res);
}

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));
        }

        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);
}

static int
timeout_next(struct event_base *base, struct timeval **tv_p)
{
        struct timeval now;
        struct event *ev;
        struct timeval *tv = *tv_p;

        if ((ev = min_heap_top(&base->timeheap)) == NULL) {
                /* if no time-based events are active wait for I/O */
                *tv_p = NULL;
                return (0);
        }

        if (gettime(base, &now) == -1)
                return (-1);

        if (evutil_timercmp(&ev->ev_timeout, &now, <=)) {
                evutil_timerclear(tv);
                return (0);
        }

        evutil_timersub(&ev->ev_timeout, &now, tv);

        assert(tv->tv_sec >= 0);
        assert(tv->tv_usec >= 0);

        event_debug(("timeout_next: in %ld seconds", tv->tv_sec));
        return (0);
}

/*
 * Determines if the time is running backwards by comparing the current
 * time against the last time we checked.  Not needed when using clock
 * monotonic.
 */

static void
timeout_correct(struct event_base *base, struct timeval *tv)
{
        struct event **pev;
        unsigned int size;
        struct timeval off;

        if (use_monotonic)
                return;

        /* Check if time is running backwards */
        gettime(base, tv);
        if (evutil_timercmp(tv, &base->event_tv, >=)) {
                base->event_tv = *tv;
                return;
        }

        event_debug(("%s: time is running backwards, corrected",
                    __func__));
        evutil_timersub(&base->event_tv, tv, &off);

        /*
         * We can modify the key element of the node without destroying
         * the key, beause we apply it to all in the right order.
         */
        pev = base->timeheap.p;
        size = base->timeheap.n;
        for (; size-- > 0; ++pev) {
                struct timeval *ev_tv = &(**pev).ev_timeout;
                evutil_timersub(ev_tv, &off, ev_tv);
        }
        /* Now remember what the new time turned out to be. */
        base->event_tv = *tv;
}

void
timeout_process(struct event_base *base)
{
        struct timeval now;
        struct event *ev;

        if (min_heap_empty(&base->timeheap))
                return;

        gettime(base, &now);

        while ((ev = min_heap_top(&base->timeheap))) {
                if (evutil_timercmp(&ev->ev_timeout, &now, >))
                        break;

                /* 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)
{
        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)
                base->event_count--;

        ev->ev_flags &= ~queue;
        switch (queue) {
        case EVLIST_INSERTED:
                TAILQ_REMOVE(&base->eventqueue, ev, ev_next);
                break;
        case EVLIST_ACTIVE:
                base->event_count_active--;
                TAILQ_REMOVE(base->activequeues[ev->ev_pri],
                    ev, ev_active_next);
                break;
        case EVLIST_TIMEOUT:
                min_heap_erase(&base->timeheap, ev);
                break;
        default:
                event_errx(1, "%s: unknown queue %x", __func__, queue);
        }
}

void
event_queue_insert(struct event_base *base, struct event *ev, int queue)
{
        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)
                base->event_count++;

        ev->ev_flags |= queue;
        switch (queue) {
        case EVLIST_INSERTED:
                TAILQ_INSERT_TAIL(&base->eventqueue, ev, ev_next);
                break;
        case EVLIST_ACTIVE:
                base->event_count_active++;
                TAILQ_INSERT_TAIL(base->activequeues[ev->ev_pri],
                    ev,ev_active_next);
                break;
        case EVLIST_TIMEOUT: {
                min_heap_push(&base->timeheap, ev);
                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);
}