event.c

/*
 * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
 * Copyright (c) 2007-2012 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.
 */
#include "event2/event-config.h"

#ifdef WIN32
#include <winsock2.h>
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#endif
#include <sys/types.h>
#if !defined(WIN32) && defined(_EVENT_HAVE_SYS_TIME_H)
#include <sys/time.h>
#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 <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"
#include "iocp-internal.h"
#include "changelist-internal.h"
#include "ht-internal.h"
#include "util-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

/* Array of backends 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; deprecated */
struct event_base *event_global_current_base_ = NULL;
#define current_base event_global_current_base_

/* Global state */

static int use_monotonic;

/* Prototypes */
static inline int event_add_internal(struct event *ev,
    const struct timeval *tv, int tv_is_absolute);
static inline int event_del_internal(struct event *ev);

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 int	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 inline void	event_signal_closure(struct event_base *, struct event *ev);
static inline void	event_persist_closure(struct event_base *, struct event *ev);

static int	evthread_notify_base(struct event_base *base);

#ifndef _EVENT_DISABLE_DEBUG_MODE
/* These functions implement a hashtable of which 'struct event *' structures
 * have been setup or added.  We don't want to trust the content of the struct
 * event itself, since we're trying to work through cases where an event gets
 * clobbered or freed.  Instead, we keep a hashtable indexed by the pointer.
 */

struct event_debug_entry {
	HT_ENTRY(event_debug_entry) node;
	const struct event *ptr;
	unsigned added : 1;
};

static inline unsigned
hash_debug_entry(const struct event_debug_entry *e)
{
	/* We need to do this silliness to convince compilers that we
	 * honestly mean to cast e->ptr to an integer, and discard any
	 * part of it that doesn't fit in an unsigned.
	 */
	unsigned u = (unsigned) ((ev_uintptr_t) e->ptr);
	/* Our hashtable implementation is pretty sensitive to low bits,
	 * and every struct event is over 64 bytes in size, so we can
	 * just say >>6. */
	return (u >> 6);
}

static inline int
eq_debug_entry(const struct event_debug_entry *a,
    const struct event_debug_entry *b)
{
	return a->ptr == b->ptr;
}

int _event_debug_mode_on = 0;
/* Set if it's too late to enable event_debug_mode. */
static int event_debug_mode_too_late = 0;
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
static void *_event_debug_map_lock = NULL;
#endif
static HT_HEAD(event_debug_map, event_debug_entry) global_debug_map =
	HT_INITIALIZER();

HT_PROTOTYPE(event_debug_map, event_debug_entry, node, hash_debug_entry,
    eq_debug_entry)
HT_GENERATE(event_debug_map, event_debug_entry, node, hash_debug_entry,
    eq_debug_entry, 0.5, mm_malloc, mm_realloc, mm_free)

/* Macro: record that ev is now setup (that is, ready for an add) */
#define _event_debug_note_setup(ev) do {				\
	if (_event_debug_mode_on) {					\
		struct event_debug_entry *dent,find;			\
		find.ptr = (ev);					\
		EVLOCK_LOCK(_event_debug_map_lock, 0);			\
		dent = HT_FIND(event_debug_map, &global_debug_map, &find); \
		if (dent) {						\
			dent->added = 0;				\
		} else {						\
			dent = mm_malloc(sizeof(*dent));		\
			if (!dent)					\
				event_err(1,				\
				    "Out of memory in debugging code");	\
			dent->ptr = (ev);				\
			dent->added = 0;				\
			HT_INSERT(event_debug_map, &global_debug_map, dent); \
		}							\
		EVLOCK_UNLOCK(_event_debug_map_lock, 0);		\
	}								\
	event_debug_mode_too_late = 1;					\
	} while (0)
/* Macro: record that ev is no longer setup */
#define _event_debug_note_teardown(ev) do {				\
	if (_event_debug_mode_on) {					\
		struct event_debug_entry *dent,find;			\
		find.ptr = (ev);					\
		EVLOCK_LOCK(_event_debug_map_lock, 0);			\
		dent = HT_REMOVE(event_debug_map, &global_debug_map, &find); \
		if (dent)						\
			mm_free(dent);					\
		EVLOCK_UNLOCK(_event_debug_map_lock, 0);		\
	}								\
	event_debug_mode_too_late = 1;					\
	} while (0)
/* Macro: record that ev is now added */
#define _event_debug_note_add(ev)	do {				\
	if (_event_debug_mode_on) {					\
		struct event_debug_entry *dent,find;			\
		find.ptr = (ev);					\
		EVLOCK_LOCK(_event_debug_map_lock, 0);			\
		dent = HT_FIND(event_debug_map, &global_debug_map, &find); \
		if (dent) {						\
			dent->added = 1;				\
		} else {						\
			event_errx(_EVENT_ERR_ABORT,			\
			    "%s: noting an add on a non-setup event %p" \
			    " (events: 0x%x, fd: %d, flags: 0x%x)",	\
			    __func__, (ev), (ev)->ev_events,		\
			    (ev)->ev_fd, (ev)->ev_flags);		\
		}							\
		EVLOCK_UNLOCK(_event_debug_map_lock, 0);		\
	}								\
	event_debug_mode_too_late = 1;					\
	} while (0)
/* Macro: record that ev is no longer added */
#define _event_debug_note_del(ev) do {					\
	if (_event_debug_mode_on) {					\
		struct event_debug_entry *dent,find;			\
		find.ptr = (ev);					\
		EVLOCK_LOCK(_event_debug_map_lock, 0);			\
		dent = HT_FIND(event_debug_map, &global_debug_map, &find); \
		if (dent) {						\
			dent->added = 0;				\
		} else {						\
			event_errx(_EVENT_ERR_ABORT,			\
			    "%s: noting a del on a non-setup event %p"	\
			    " (events: 0x%x, fd: %d, flags: 0x%x)",	\
			    __func__, (ev), (ev)->ev_events,		\
			    (ev)->ev_fd, (ev)->ev_flags);		\
		}							\
		EVLOCK_UNLOCK(_event_debug_map_lock, 0);		\
	}								\
	event_debug_mode_too_late = 1;					\
	} while (0)
/* Macro: assert that ev is setup (i.e., okay to add or inspect) */
#define _event_debug_assert_is_setup(ev) do {				\
	if (_event_debug_mode_on) {					\
		struct event_debug_entry *dent,find;			\
		find.ptr = (ev);					\
		EVLOCK_LOCK(_event_debug_map_lock, 0);			\
		dent = HT_FIND(event_debug_map, &global_debug_map, &find); \
		if (!dent) {						\
			event_errx(_EVENT_ERR_ABORT,			\
			    "%s called on a non-initialized event %p"	\
			    " (events: 0x%x, fd: %d, flags: 0x%x)",	\
			    __func__, (ev), (ev)->ev_events,		\
			    (ev)->ev_fd, (ev)->ev_flags);		\
		}							\
		EVLOCK_UNLOCK(_event_debug_map_lock, 0);		\
	}								\
	} while (0)
/* Macro: assert that ev is not added (i.e., okay to tear down or set
 * up again) */
#define _event_debug_assert_not_added(ev) do {				\
	if (_event_debug_mode_on) {					\
		struct event_debug_entry *dent,find;			\
		find.ptr = (ev);					\
		EVLOCK_LOCK(_event_debug_map_lock, 0);			\
		dent = HT_FIND(event_debug_map, &global_debug_map, &find); \
		if (dent && dent->added) {				\
			event_errx(_EVENT_ERR_ABORT,			\
			    "%s called on an already added event %p"	\
			    " (events: 0x%x, fd: %d, flags: 0x%x)",	\
			    __func__, (ev), (ev)->ev_events,		\
			    (ev)->ev_fd, (ev)->ev_flags);		\
		}							\
		EVLOCK_UNLOCK(_event_debug_map_lock, 0);		\
	}								\
	} while (0)
#else
#define _event_debug_note_setup(ev) \
	((void)0)
#define _event_debug_note_teardown(ev) \
	((void)0)
#define _event_debug_note_add(ev) \
	((void)0)
#define _event_debug_note_del(ev) \
	((void)0)
#define _event_debug_assert_is_setup(ev) \
	((void)0)
#define _event_debug_assert_not_added(ev) \
	((void)0)
#endif

#define EVENT_BASE_ASSERT_LOCKED(base)		\
	EVLOCK_ASSERT_LOCKED((base)->th_base_lock)

/* The first time this function is called, it sets use_monotonic to 1
 * if we have a clock function that supports monotonic time */
static void
detect_monotonic(void)
{
#if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
	struct timespec	ts;
	static int use_monotonic_initialized = 0;

	if (use_monotonic_initialized)
		return;

	if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
		use_monotonic = 1;

	use_monotonic_initialized = 1;
#endif
}

/* How often (in seconds) do we check for changes in wall clock time relative
 * to monotonic time?  Set this to -1 for 'never.' */
#define CLOCK_SYNC_INTERVAL -1

/** Set 'tp' to the current time according to 'base'.  We must hold the lock
 * on 'base'.  If there is a cached time, return it.  Otherwise, use
 * clock_gettime or gettimeofday as appropriate to find out the right time.
 * Return 0 on success, -1 on failure.
 */
static int
gettime(struct event_base *base, struct timeval *tp)
{
	EVENT_BASE_ASSERT_LOCKED(base);

	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;
		if (base->last_updated_clock_diff + CLOCK_SYNC_INTERVAL
		    < ts.tv_sec) {
			struct timeval tv;
			evutil_gettimeofday(&tv,NULL);
			evutil_timersub(&tv, tp, &base->tv_clock_diff);
			base->last_updated_clock_diff = ts.tv_sec;
		}

		return (0);
	}
#endif

	return (evutil_gettimeofday(tp, NULL));
}

int
event_base_gettimeofday_cached(struct event_base *base, struct timeval *tv)
{
	int r;
	if (!base) {
		base = current_base;
		if (!current_base)
			return evutil_gettimeofday(tv, NULL);
	}

	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	if (base->tv_cache.tv_sec == 0) {
		r = evutil_gettimeofday(tv, NULL);
	} else {
#if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
		evutil_timeradd(&base->tv_cache, &base->tv_clock_diff, tv);
#else
		*tv = base->tv_cache;
#endif
		r = 0;
	}
	EVBASE_RELEASE_LOCK(base, th_base_lock);
	return r;
}

/** Make 'base' have no current cached time. */
static inline void
clear_time_cache(struct event_base *base)
{
	base->tv_cache.tv_sec = 0;
}

/** Replace the cached time in 'base' with the current time. */
static inline void
update_time_cache(struct event_base *base)
{
	base->tv_cache.tv_sec = 0;
	if (!(base->flags & EVENT_BASE_FLAG_NO_CACHE_TIME))
	    gettime(base, &base->tv_cache);
}

struct event_base *
event_init(void)
{
	struct event_base *base = event_base_new_with_config(NULL);

	if (base == NULL) {
		event_errx(1, "%s: Unable to construct event_base", __func__);
		return NULL;
	}

	current_base = base;

	return (base);
}

struct event_base *
event_base_new(void)
{
	struct event_base *base = NULL;
	struct event_config *cfg = event_config_new();
	if (cfg) {
		base = event_base_new_with_config(cfg);
		event_config_free(cfg);
	}
	return base;
}

/** Return true iff 'method' is the name of a method that 'cfg' tells us to
 * avoid. */
static int
event_config_is_avoided_method(const 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);
}

/** Return true iff 'method' is disabled according to the environment. */
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] = EVUTIL_TOUPPER(environment[i]);
	/* Note that evutil_getenv() ignores the environment entirely if
	 * we're setuid */
	return (evutil_getenv(environment) != NULL);
}

int
event_base_get_features(const struct event_base *base)
{
	return base->evsel->features;
}

void
event_deferred_cb_queue_init(struct deferred_cb_queue *cb)
{
	memset(cb, 0, sizeof(struct deferred_cb_queue));
	TAILQ_INIT(&cb->deferred_cb_list);
}

/** Helper for the deferred_cb queue: wake up the event base. */
static void
notify_base_cbq_callback(struct deferred_cb_queue *cb, void *baseptr)
{
	struct event_base *base = baseptr;
	if (EVBASE_NEED_NOTIFY(base))
		evthread_notify_base(base);
}

struct deferred_cb_queue *
event_base_get_deferred_cb_queue(struct event_base *base)
{
	return base ? &base->defer_queue : NULL;
}

void
event_enable_debug_mode(void)
{
#ifndef _EVENT_DISABLE_DEBUG_MODE
	if (_event_debug_mode_on)
		event_errx(1, "%s was called twice!", __func__);
	if (event_debug_mode_too_late)
		event_errx(1, "%s must be called *before* creating any events "
		    "or event_bases",__func__);

	_event_debug_mode_on = 1;

	HT_INIT(event_debug_map, &global_debug_map);
#endif
}

#if 0
void
event_disable_debug_mode(void)
{
	struct event_debug_entry **ent, *victim;

	EVLOCK_LOCK(_event_debug_map_lock, 0);
	for (ent = HT_START(event_debug_map, &global_debug_map); ent; ) {
		victim = *ent;
		ent = HT_NEXT_RMV(event_debug_map,&global_debug_map, ent);
		mm_free(victim);
	}
	HT_CLEAR(event_debug_map, &global_debug_map);
	EVLOCK_UNLOCK(_event_debug_map_lock , 0);
}
#endif

struct event_base *
event_base_new_with_config(const struct event_config *cfg)
{
	int i;
	struct event_base *base;
	int should_check_environment;

#ifndef _EVENT_DISABLE_DEBUG_MODE
	event_debug_mode_too_late = 1;
#endif

	if ((base = mm_calloc(1, sizeof(struct event_base))) == NULL) {
		event_warn("%s: calloc", __func__);
		return NULL;
	}
	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->th_notify_fd[0] = -1;
	base->th_notify_fd[1] = -1;

	event_deferred_cb_queue_init(&base->defer_queue);
	base->defer_queue.notify_fn = notify_base_cbq_callback;
	base->defer_queue.notify_arg = base;
	if (cfg)
		base->flags = cfg->flags;

	evmap_io_initmap(&base->io);
	evmap_signal_initmap(&base->sigmap);
	event_changelist_init(&base->changelist);

	base->evbase = NULL;

	should_check_environment =
	    !(cfg && (cfg->flags & EVENT_BASE_FLAG_IGNORE_ENV));

	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 (should_check_environment &&
		    event_is_method_disabled(eventops[i]->name))
			continue;

		base->evsel = eventops[i];

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

	if (base->evbase == NULL) {
		event_warnx("%s: no event mechanism available",
		    __func__);
		base->evsel = NULL;
		event_base_free(base);
		return NULL;
	}

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

	/* allocate a single active event queue */
	if (event_base_priority_init(base, 1) < 0) {
		event_base_free(base);
		return NULL;
	}

	/* prepare for threading */

#ifndef _EVENT_DISABLE_THREAD_SUPPORT
	if (EVTHREAD_LOCKING_ENABLED() &&
	    (!cfg || !(cfg->flags & EVENT_BASE_FLAG_NOLOCK))) {
		int r;
		EVTHREAD_ALLOC_LOCK(base->th_base_lock,
		    EVTHREAD_LOCKTYPE_RECURSIVE);
		base->defer_queue.lock = base->th_base_lock;
		EVTHREAD_ALLOC_COND(base->current_event_cond);
		r = evthread_make_base_notifiable(base);
		if (r<0) {
			event_warnx("%s: Unable to make base notifiable.", __func__);
			event_base_free(base);
			return NULL;
		}
	}
#endif

#ifdef WIN32
	if (cfg && (cfg->flags & EVENT_BASE_FLAG_STARTUP_IOCP))
		event_base_start_iocp(base, cfg->n_cpus_hint);
#endif

	return (base);
}

int
event_base_start_iocp(struct event_base *base, int n_cpus)
{
#ifdef WIN32
	if (base->iocp)
		return 0;
	base->iocp = event_iocp_port_launch(n_cpus);
	if (!base->iocp) {
		event_warnx("%s: Couldn't launch IOCP", __func__);
		return -1;
	}
	return 0;
#else
	return -1;
#endif
}

void
event_base_stop_iocp(struct event_base *base)
{
#ifdef WIN32
	int rv;

	if (!base->iocp)
		return;
	rv = event_iocp_shutdown(base->iocp, -1);
	EVUTIL_ASSERT(rv >= 0);
	base->iocp = NULL;
#endif
}

void
event_base_free(struct event_base *base)
{
	int i, n_deleted=0;
	struct event *ev;
	/* XXXX grab the lock? If there is contention when one thread frees
	 * the base, then the contending thread will be very sad soon. */

	/* event_base_free(NULL) is how to free the current_base if we
	 * made it with event_init and forgot to hold a reference to it. */
	if (base == NULL && current_base)
		base = current_base;
	/* If we're freeing current_base, there won't be a current_base. */
	if (base == current_base)
		current_base = NULL;
	/* Don't actually free NULL. */
	if (base == NULL) {
		event_warnx("%s: no base to free", __func__);
		return;
	}
	/* XXX(niels) - check for internal events first */

#ifdef WIN32
	event_base_stop_iocp(base);
#endif

	/* 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]);
		if (base->th_notify_fd[1] != -1)
			EVUTIL_CLOSESOCKET(base->th_notify_fd[1]);
		base->th_notify_fd[0] = -1;
		base->th_notify_fd[1] = -1;
		event_debug_unassign(&base->th_notify);
	}

	/* 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->n_common_timeouts; ++i) {
		struct common_timeout_list *ctl =
		    base->common_timeout_queues[i];
		event_del(&ctl->timeout_event); /* Internal; doesn't count */
		event_debug_unassign(&ctl->timeout_event);
		for (ev = TAILQ_FIRST(&ctl->events); ev; ) {
			struct event *next = TAILQ_NEXT(ev,
			    ev_timeout_pos.ev_next_with_common_timeout);
			if (!(ev->ev_flags & EVLIST_INTERNAL)) {
				event_del(ev);
				++n_deleted;
			}
			ev = next;
		}
		mm_free(ctl);
	}
	if (base->common_timeout_queues)
		mm_free(base->common_timeout_queues);

	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)
		EVUTIL_ASSERT(TAILQ_EMPTY(&base->activequeues[i]));

	EVUTIL_ASSERT(min_heap_empty(&base->timeheap));
	min_heap_dtor(&base->timeheap);

	mm_free(base->activequeues);

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

	evmap_io_clear(&base->io);
	evmap_signal_clear(&base->sigmap);
	event_changelist_freemem(&base->changelist);

	EVTHREAD_FREE_LOCK(base->th_base_lock, EVTHREAD_LOCKTYPE_RECURSIVE);
	EVTHREAD_FREE_COND(base->current_event_cond);

	mm_free(base);
}

/* reinitialize the event base after a fork */
int
event_reinit(struct event_base *base)
{
	const struct eventop *evsel;
	int res = 0;
	struct event *ev;
	int was_notifiable = 0;

	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

	evsel = base->evsel;

#if 0
	/* Right now, reinit always takes effect, since even if the
	   backend doesn't require it, the signal socketpair code does.

	   XXX
	 */
	/* check if this event mechanism requires reinit */
	if (!evsel->need_reinit)
		goto done;
#endif

	/* 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);
		if (base->sig.ev_signal_pair[0] != -1)
			EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[0]);
		if (base->sig.ev_signal_pair[1] != -1)
			EVUTIL_CLOSESOCKET(base->sig.ev_signal_pair[1]);
		base->sig.ev_signal_added = 0;
	}
	if (base->th_notify_fd[0] != -1) {
		/* we cannot call event_del here because the base has
		 * not been reinitialized yet. */
		was_notifiable = 1;
		event_queue_remove(base, &base->th_notify,
		    EVLIST_INSERTED);
		if (base->th_notify.ev_flags & EVLIST_ACTIVE)
			event_queue_remove(base, &base->th_notify,
			    EVLIST_ACTIVE);
		base->sig.ev_signal_added = 0;
		EVUTIL_CLOSESOCKET(base->th_notify_fd[0]);
		if (base->th_notify_fd[1] != -1)
			EVUTIL_CLOSESOCKET(base->th_notify_fd[1]);
		base->th_notify_fd[0] = -1;
		base->th_notify_fd[1] = -1;
		event_debug_unassign(&base->th_notify);
	}

	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__);
		res = -1;
		goto done;
	}

	event_changelist_freemem(&base->changelist); /* XXX */
	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 (ev == &base->sig.ev_signal) {
				/* If we run into the ev_signal event, it's only
				 * in eventqueue because some signal event was
				 * added, which made evsig_add re-add ev_signal.
				 * So don't double-add it. */
				continue;
			}
			if (evmap_io_add(base, ev->ev_fd, ev) == -1)
				res = -1;
		} else if (ev->ev_events & EV_SIGNAL) {
			if (evmap_signal_add(base, (int)ev->ev_fd, ev) == -1)
				res = -1;
		}
	}

	if (was_notifiable && res == 0)
		res = evthread_make_base_notifiable(base);

done:
	EVBASE_RELEASE_LOCK(base, th_base_lock);
	return (res);
}

const char **
event_get_supported_methods(void)
{
	static const char **methods = NULL;
	const struct eventop **method;
	const char **tmp;
	int i = 0, k;

	/* count all methods */
	for (method = &eventops[0]; *method != NULL; ++method) {
		++i;
	}

	/* allocate one more than we need for the NULL pointer */
	tmp = mm_calloc((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) {
		tmp[i++] = eventops[k]->name;
	}
	tmp[i] = NULL;

	if (methods != NULL)
		mm_free((char**)methods);

	methods = tmp;

	return (methods);
}

struct event_config *
event_config_new(void)
{
	struct event_config *cfg = mm_calloc(1, sizeof(*cfg));

	if (cfg == NULL)
		return (NULL);

	TAILQ_INIT(&cfg->entries);

	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_set_flag(struct event_config *cfg, int flag)
{
	if (!cfg)
		return -1;
	cfg->flags |= flag;
	return 0;
}

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,
    int features)
{
	if (!cfg)
		return (-1);
	cfg->require_features = features;
	return (0);
}

int
event_config_set_num_cpus_hint(struct event_config *cfg, int cpus)
{
	if (!cfg)
		return (-1);
	cfg->n_cpus_hint = cpus;
	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 (N_ACTIVE_CALLBACKS(base) || npriorities < 1
	    || npriorities >= EVENT_MAX_PRIORITIES)
		return (-1);

	if (npriorities == base->nactivequeues)
		return (0);

	if (base->nactivequeues) {
		mm_free(base->activequeues);
		base->nactivequeues = 0;
	}

	/* Allocate our priority queues */
	base->activequeues = (struct event_list *)
	  mm_calloc(npriorities, sizeof(struct event_list));
	if (base->activequeues == NULL) {
		event_warn("%s: calloc", __func__);
		return (-1);
	}
	base->nactivequeues = npriorities;

	for (i = 0; i < base->nactivequeues; ++i) {
		TAILQ_INIT(&base->activequeues[i]);
	}

	return (0);
}

/* Returns true iff we're currently watching any events. */
static int
event_haveevents(struct event_base *base)
{
	/* Caller must hold th_base_lock */
	return (base->virtual_event_count > 0 || base->event_count > 0);
}

/* "closure" function called when processing active signal events */
static inline void
event_signal_closure(struct event_base *base, struct event *ev)
{
	short ncalls;
	int should_break;

	/* Allows deletes to work */
	ncalls = ev->ev_ncalls;
	if (ncalls != 0)
		ev->ev_pncalls = &ncalls;
	EVBASE_RELEASE_LOCK(base, th_base_lock);
	while (ncalls) {
		ncalls--;
		ev->ev_ncalls = ncalls;
		if (ncalls == 0)
			ev->ev_pncalls = NULL;
		(*ev->ev_callback)(ev->ev_fd, ev->ev_res, ev->ev_arg);

		EVBASE_ACQUIRE_LOCK(base, th_base_lock);
		should_break = base->event_break;
		EVBASE_RELEASE_LOCK(base, th_base_lock);

		if (should_break) {
			if (ncalls != 0)
				ev->ev_pncalls = NULL;
			return;
		}
	}
}

/* Common timeouts are special timeouts that are handled as queues rather than
 * in the minheap.  This is more efficient than the minheap if we happen to
 * know that we're going to get several thousands of timeout events all with
 * the same timeout value.
 *
 * Since all our timeout handling code assumes timevals can be copied,
 * assigned, etc, we can't use "magic pointer" to encode these common
 * timeouts.  Searching through a list to see if every timeout is common could
 * also get inefficient.  Instead, we take advantage of the fact that tv_usec
 * is 32 bits long, but only uses 20 of those bits (since it can never be over
 * 999999.)  We use the top bits to encode 4 bites of magic number, and 8 bits
 * of index into the event_base's aray of common timeouts.
 */

#define MICROSECONDS_MASK       COMMON_TIMEOUT_MICROSECONDS_MASK
#define COMMON_TIMEOUT_IDX_MASK 0x0ff00000
#define COMMON_TIMEOUT_IDX_SHIFT 20
#define COMMON_TIMEOUT_MASK     0xf0000000
#define COMMON_TIMEOUT_MAGIC    0x50000000

#define COMMON_TIMEOUT_IDX(tv) \
	(((tv)->tv_usec & COMMON_TIMEOUT_IDX_MASK)>>COMMON_TIMEOUT_IDX_SHIFT)

/** Return true iff if 'tv' is a common timeout in 'base' */
static inline int
is_common_timeout(const struct timeval *tv,
    const struct event_base *base)
{
	int idx;
	if ((tv->tv_usec & COMMON_TIMEOUT_MASK) != COMMON_TIMEOUT_MAGIC)
		return 0;
	idx = COMMON_TIMEOUT_IDX(tv);
	return idx < base->n_common_timeouts;
}

/* True iff tv1 and tv2 have the same common-timeout index, or if neither
 * one is a common timeout. */
static inline int
is_same_common_timeout(const struct timeval *tv1, const struct timeval *tv2)
{
	return (tv1->tv_usec & ~MICROSECONDS_MASK) ==
	    (tv2->tv_usec & ~MICROSECONDS_MASK);
}

/** Requires that 'tv' is a common timeout.  Return the corresponding
 * common_timeout_list. */
static inline struct common_timeout_list *
get_common_timeout_list(struct event_base *base, const struct timeval *tv)
{
	return base->common_timeout_queues[COMMON_TIMEOUT_IDX(tv)];
}

#if 0
static inline int
common_timeout_ok(const struct timeval *tv,
    struct event_base *base)
{
	const struct timeval *expect =
	    &get_common_timeout_list(base, tv)->duration;
	return tv->tv_sec == expect->tv_sec &&
	    tv->tv_usec == expect->tv_usec;
}
#endif

/* Add the timeout for the first event in given common timeout list to the
 * event_base's minheap. */
static void
common_timeout_schedule(struct common_timeout_list *ctl,
    const struct timeval *now, struct event *head)
{
	struct timeval timeout = head->ev_timeout;
	timeout.tv_usec &= MICROSECONDS_MASK;
	event_add_internal(&ctl->timeout_event, &timeout, 1);
}

/* Callback: invoked when the timeout for a common timeout queue triggers.
 * This means that (at least) the first event in that queue should be run,
 * and the timeout should be rescheduled if there are more events. */
static void
common_timeout_callback(evutil_socket_t fd, short what, void *arg)
{
	struct timeval now;
	struct common_timeout_list *ctl = arg;
	struct event_base *base = ctl->base;
	struct event *ev = NULL;
	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	gettime(base, &now);
	while (1) {
		ev = TAILQ_FIRST(&ctl->events);
		if (!ev || ev->ev_timeout.tv_sec > now.tv_sec ||
		    (ev->ev_timeout.tv_sec == now.tv_sec &&
			(ev->ev_timeout.tv_usec&MICROSECONDS_MASK) > now.tv_usec))
			break;
		event_del_internal(ev);
		event_active_nolock(ev, EV_TIMEOUT, 1);
	}
	if (ev)
		common_timeout_schedule(ctl, &now, ev);
	EVBASE_RELEASE_LOCK(base, th_base_lock);
}

#define MAX_COMMON_TIMEOUTS 256

const struct timeval *
event_base_init_common_timeout(struct event_base *base,
    const struct timeval *duration)
{
	int i;
	struct timeval tv;
	const struct timeval *result=NULL;
	struct common_timeout_list *new_ctl;

	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	if (duration->tv_usec > 1000000) {
		memcpy(&tv, duration, sizeof(struct timeval));
		if (is_common_timeout(duration, base))
			tv.tv_usec &= MICROSECONDS_MASK;
		tv.tv_sec += tv.tv_usec / 1000000;
		tv.tv_usec %= 1000000;
		duration = &tv;
	}
	for (i = 0; i < base->n_common_timeouts; ++i) {
		const struct common_timeout_list *ctl =
		    base->common_timeout_queues[i];
		if (duration->tv_sec == ctl->duration.tv_sec &&
		    duration->tv_usec ==
		    (ctl->duration.tv_usec & MICROSECONDS_MASK)) {
			EVUTIL_ASSERT(is_common_timeout(&ctl->duration, base));
			result = &ctl->duration;
			goto done;
		}
	}
	if (base->n_common_timeouts == MAX_COMMON_TIMEOUTS) {
		event_warnx("%s: Too many common timeouts already in use; "
		    "we only support %d per event_base", __func__,
		    MAX_COMMON_TIMEOUTS);
		goto done;
	}
	if (base->n_common_timeouts_allocated == base->n_common_timeouts) {
		int n = base->n_common_timeouts < 16 ? 16 :
		    base->n_common_timeouts*2;
		struct common_timeout_list **newqueues =
		    mm_realloc(base->common_timeout_queues,
			n*sizeof(struct common_timeout_queue *));
		if (!newqueues) {
			event_warn("%s: realloc",__func__);
			goto done;
		}
		base->n_common_timeouts_allocated = n;
		base->common_timeout_queues = newqueues;
	}
	new_ctl = mm_calloc(1, sizeof(struct common_timeout_list));
	if (!new_ctl) {
		event_warn("%s: calloc",__func__);
		goto done;
	}
	TAILQ_INIT(&new_ctl->events);
	new_ctl->duration.tv_sec = duration->tv_sec;
	new_ctl->duration.tv_usec =
	    duration->tv_usec | COMMON_TIMEOUT_MAGIC |
	    (base->n_common_timeouts << COMMON_TIMEOUT_IDX_SHIFT);
	evtimer_assign(&new_ctl->timeout_event, base,
	    common_timeout_callback, new_ctl);
	new_ctl->timeout_event.ev_flags |= EVLIST_INTERNAL;
	event_priority_set(&new_ctl->timeout_event, 0);
	new_ctl->base = base;
	base->common_timeout_queues[base->n_common_timeouts++] = new_ctl;
	result = &new_ctl->duration;

done:
	if (result)
		EVUTIL_ASSERT(is_common_timeout(result, base));

	EVBASE_RELEASE_LOCK(base, th_base_lock);
	return result;
}

/* Closure function invoked when we're activating a persistent event. */
static inline 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) {
		/* If there was a timeout, we want it to run at an interval of
		 * ev_io_timeout after the last time it was _scheduled_ for,
		 * not ev_io_timeout after _now_.  If it fired for another
		 * reason, though, the timeout ought to start ticking _now_. */
		struct timeval run_at, relative_to, delay, now;
		ev_uint32_t usec_mask = 0;
		EVUTIL_ASSERT(is_same_common_timeout(&ev->ev_timeout,
			&ev->ev_io_timeout));
		gettime(base, &now);
		if (is_common_timeout(&ev->ev_timeout, base)) {
			delay = ev->ev_io_timeout;
			usec_mask = delay.tv_usec & ~MICROSECONDS_MASK;
			delay.tv_usec &= MICROSECONDS_MASK;
			if (ev->ev_res & EV_TIMEOUT) {
				relative_to = ev->ev_timeout;
				relative_to.tv_usec &= MICROSECONDS_MASK;
			} else {
				relative_to = now;
			}
		} else {
			delay = ev->ev_io_timeout;
			if (ev->ev_res & EV_TIMEOUT) {
				relative_to = ev->ev_timeout;
			} else {
				relative_to = now;
			}
		}
		evutil_timeradd(&relative_to, &delay, &run_at);
		if (evutil_timercmp(&run_at, &now, <)) {
			/* Looks like we missed at least one invocation due to
			 * a clock jump, not running the event loop for a
			 * while, really slow callbacks, or
			 * something. Reschedule relative to now.
			 */
			evutil_timeradd(&now, &delay, &run_at);
		}
		run_at.tv_usec |= usec_mask;
		event_add_internal(ev, &run_at, 1);
	}
	EVBASE_RELEASE_LOCK(base, th_base_lock);
	(*ev->ev_callback)(ev->ev_fd, ev->ev_res, ev->ev_arg);
}

/*
  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;

	EVUTIL_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));

#ifndef _EVENT_DISABLE_THREAD_SUPPORT
		base->current_event = ev;
		base->current_event_waiters = 0;
#endif

		switch (ev->ev_closure) {
		case EV_CLOSURE_SIGNAL:
			event_signal_closure(base, ev);
			break;
		case EV_CLOSURE_PERSIST:
			event_persist_closure(base, ev);
			break;
		default:
		case EV_CLOSURE_NONE:
			EVBASE_RELEASE_LOCK(base, th_base_lock);
			(*ev->ev_callback)(
				ev->ev_fd, ev->ev_res, ev->ev_arg);
			break;
		}

		EVBASE_ACQUIRE_LOCK(base, th_base_lock);
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
		base->current_event = NULL;
		if (base->current_event_waiters) {
			base->current_event_waiters = 0;
			EVTHREAD_COND_BROADCAST(base->current_event_cond);
		}
#endif

		if (base->event_break)
			return -1;
		if (base->event_continue)
			break;
	}
	return count;
}

/*
   Process up to MAX_DEFERRED of the defered_cb entries in 'queue'.  If
   *breakptr becomes set to 1, stop.  Requires that we start out holding
   the lock on 'queue'; releases the lock around 'queue' for each deferred_cb
   we process.
 */
static int
event_process_deferred_callbacks(struct deferred_cb_queue *queue, int *breakptr)
{
	int count = 0;
	struct deferred_cb *cb;

#define MAX_DEFERRED 16
	while ((cb = TAILQ_FIRST(&queue->deferred_cb_list))) {
		cb->queued = 0;
		TAILQ_REMOVE(&queue->deferred_cb_list, cb, cb_next);
		--queue->active_count;
		UNLOCK_DEFERRED_QUEUE(queue);

		cb->cb(cb, cb->arg);

		LOCK_DEFERRED_QUEUE(queue);
		if (*breakptr)
			return -1;
		if (++count == MAX_DEFERRED)
			break;
	}
#undef MAX_DEFERRED
	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 int
event_process_active(struct event_base *base)
{
	/* Caller must hold th_base_lock */
	struct event_list *activeq = NULL;
	int i, c = 0;

	for (i = 0; i < base->nactivequeues; ++i) {
		if (TAILQ_FIRST(&base->activequeues[i]) != NULL) {
			base->event_running_priority = i;
			activeq = &base->activequeues[i];
			c = event_process_active_single_queue(base, activeq);
			if (c < 0) {
				base->event_running_priority = -1;
				return -1;
			} 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->defer_queue,&base->event_break);
	base->event_running_priority = -1;
	return c;
}

/*
 * Wait continuously 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(const struct event_base *base)
{
	EVUTIL_ASSERT(base);
	return (base->evsel->name);
}

/** Callback: used to implement event_base_loopexit by telling the event_base
 * that it's time to exit its loop. */
static void
event_loopexit_cb(evutil_socket_t fd, short what, void *arg)
{
	struct event_base *base = arg;
	base->event_gotterm = 1;
}

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)
{
	int r = 0;
	if (event_base == NULL)
		return (-1);

	EVBASE_ACQUIRE_LOCK(event_base, th_base_lock);
	event_base->event_break = 1;

	if (EVBASE_NEED_NOTIFY(event_base)) {
		r = evthread_notify_base(event_base);
	} else {
		r = (0);
	}
	EVBASE_RELEASE_LOCK(event_base, th_base_lock);
	return r;
}

int
event_base_got_break(struct event_base *event_base)
{
	int res;
	EVBASE_ACQUIRE_LOCK(event_base, th_base_lock);
	res = event_base->event_break;
	EVBASE_RELEASE_LOCK(event_base, th_base_lock);
	return res;
}

int
event_base_got_exit(struct event_base *event_base)
{
	int res;
	EVBASE_ACQUIRE_LOCK(event_base, th_base_lock);
	res = event_base->event_gotterm;
	EVBASE_RELEASE_LOCK(event_base, th_base_lock);
	return res;
}

/* 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, retval = 0;

	/* Grab the lock.  We will release it inside evsel.dispatch, and again
	 * as we invoke user callbacks. */
	EVBASE_ACQUIRE_LOCK(base, th_base_lock);

	if (base->running_loop) {
		event_warnx("%s: reentrant invocation.  Only one event_base_loop"
		    " can run on each event_base at once.", __func__);
		EVBASE_RELEASE_LOCK(base, th_base_lock);
		return -1;
	}

	base->running_loop = 1;

	clear_time_cache(base);

	if (base->sig.ev_signal_added && base->sig.ev_n_signals_added)
		evsig_set_base(base);

	done = 0;

#ifndef _EVENT_DISABLE_THREAD_SUPPORT
	base->th_owner_id = EVTHREAD_GET_ID();
#endif

	base->event_gotterm = base->event_break = 0;

	while (!done) {
		base->event_continue = 0;

		/* Terminate the loop if we have been asked to */
		if (base->event_gotterm) {
			break;
		}

		if (base->event_break) {
			break;
		}

		timeout_correct(base, &tv);

		tv_p = &tv;
		if (!N_ACTIVE_CALLBACKS(base) && !(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) && !N_ACTIVE_CALLBACKS(base)) {
			event_debug(("%s: no events registered.", __func__));
			retval = 1;
			goto done;
		}

		/* update last old time */
		gettime(base, &base->event_tv);

		clear_time_cache(base);

		res = evsel->dispatch(base, tv_p);

		if (res == -1) {
			event_debug(("%s: dispatch returned unsuccessfully.",
				__func__));
			retval = -1;
			goto done;
		}

		update_time_cache(base);

		timeout_process(base);

		if (N_ACTIVE_CALLBACKS(base)) {
			int n = event_process_active(base);
			if ((flags & EVLOOP_ONCE)
			    && N_ACTIVE_CALLBACKS(base) == 0
			    && n != 0)
				done = 1;
		} else if (flags & EVLOOP_NONBLOCK)
			done = 1;
	}
	event_debug(("%s: asked to terminate loop.", __func__));

done:
	clear_time_cache(base);
	base->running_loop = 0;

	EVBASE_RELEASE_LOCK(base, th_base_lock);

	return (retval);
}

/* 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 to implement event_base_once: invokes the user callback,
 * then deletes the allocated storage */
static void
event_once_cb(evutil_socket_t fd, short events, void *arg)
{
	struct event_once *eonce = arg;

	(*eonce->cb)(fd, events, eonce->arg);
	event_debug_unassign(&eonce->ev);
	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, or persistent
	 * events. */
	if (events & (EV_SIGNAL|EV_PERSIST))
		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);
}

int
event_assign(struct event *ev, struct event_base *base, evutil_socket_t fd, short events, void (*callback)(evutil_socket_t, short, void *), void *arg)
{
	if (!base)
		base = current_base;

	_event_debug_assert_not_added(ev);

	ev->ev_base = 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_warnx("%s: EV_SIGNAL is not compatible with "
			    "EV_READ or EV_WRITE", __func__);
			return -1;
		}
		ev->ev_closure = EV_CLOSURE_SIGNAL;
	} else {
		if (events & EV_PERSIST) {
			evutil_timerclear(&ev->ev_io_timeout);
			ev->ev_closure = EV_CLOSURE_PERSIST;
		} else {
			ev->ev_closure = EV_CLOSURE_NONE;
		}
	}

	min_heap_elem_init(ev);

	if (base != NULL) {
		/* by default, we put new events into the middle priority */
		ev->ev_pri = base->nactivequeues / 2;
	}

	_event_debug_note_setup(ev);

	return 0;
}

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);

	_event_debug_assert_is_setup(ev);

	ev->ev_base = base;
	ev->ev_pri = base->nactivequeues/2;

	return (0);
}

void
event_set(struct event *ev, evutil_socket_t fd, short events,
	  void (*callback)(evutil_socket_t, short, void *), void *arg)
{
	int r;
	r = event_assign(ev, current_base, fd, events, callback, arg);
	EVUTIL_ASSERT(r == 0);
}

struct event *
event_new(struct event_base *base, evutil_socket_t fd, short events, void (*cb)(evutil_socket_t, short, void *), void *arg)
{
	struct event *ev;
	ev = mm_malloc(sizeof(struct event));
	if (ev == NULL)
		return (NULL);
	if (event_assign(ev, base, fd, events, cb, arg) < 0) {
		mm_free(ev);
		return (NULL);
	}

	return (ev);
}

void
event_free(struct event *ev)
{
	_event_debug_assert_is_setup(ev);

	/* make sure that this event won't be coming back to haunt us. */
	event_del(ev);
	_event_debug_note_teardown(ev);
	mm_free(ev);

}

void
event_debug_unassign(struct event *ev)
{
	_event_debug_assert_not_added(ev);
	_event_debug_note_teardown(ev);

	ev->ev_flags &= ~EVLIST_INIT;
}

/*
 * 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)
{
	_event_debug_assert_is_setup(ev);

	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(const struct event *ev, short event, struct timeval *tv)
{
	int flags = 0;

	EVBASE_ACQUIRE_LOCK(ev->ev_base, th_base_lock);
	_event_debug_assert_is_setup(ev);

	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)) {
		struct timeval tmp = ev->ev_timeout;
		tmp.tv_usec &= MICROSECONDS_MASK;
#if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
		/* correctly remamp to real time */
		evutil_timeradd(&ev->ev_base->tv_clock_diff, &tmp, tv);
#else
		*tv = tmp;
#endif
	}

	EVBASE_RELEASE_LOCK(ev->ev_base, th_base_lock);

	return (flags & event);
}

int
event_initialized(const struct event *ev)
{
	if (!(ev->ev_flags & EVLIST_INIT))
		return 0;

	return 1;
}

void
event_get_assignment(const struct event *event, struct event_base **base_out, evutil_socket_t *fd_out, short *events_out, event_callback_fn *callback_out, void **arg_out)
{
	_event_debug_assert_is_setup(event);

	if (base_out)
		*base_out = event->ev_base;
	if (fd_out)
		*fd_out = event->ev_fd;
	if (events_out)
		*events_out = event->ev_events;
	if (callback_out)
		*callback_out = event->ev_callback;
	if (arg_out)
		*arg_out = event->ev_arg;
}

size_t
event_get_struct_event_size(void)
{
	return sizeof(struct event);
}

evutil_socket_t
event_get_fd(const struct event *ev)
{
	_event_debug_assert_is_setup(ev);
	return ev->ev_fd;
}

struct event_base *
event_get_base(const struct event *ev)
{
	_event_debug_assert_is_setup(ev);
	return ev->ev_base;
}

short
event_get_events(const struct event *ev)
{
	_event_debug_assert_is_setup(ev);
	return ev->ev_events;
}

event_callback_fn
event_get_callback(const struct event *ev)
{
	_event_debug_assert_is_setup(ev);
	return ev->ev_callback;
}

void *
event_get_callback_arg(const struct event *ev)
{
	_event_debug_assert_is_setup(ev);
	return ev->ev_arg;
}

int
event_add(struct event *ev, const struct timeval *tv)
{
	int res;

	if (EVUTIL_FAILURE_CHECK(!ev->ev_base)) {
		event_warnx("%s: event has no event_base set.", __func__);
		return -1;
	}

	EVBASE_ACQUIRE_LOCK(ev->ev_base, th_base_lock);

	res = event_add_internal(ev, tv, 0);

	EVBASE_RELEASE_LOCK(ev->ev_base, th_base_lock);

	return (res);
}

/* Helper callback: wake an event_base from another thread.  This version
 * works by writing a byte to one end of a socketpair, so that the event_base
 * listening on the other end will wake up as the corresponding event
 * triggers */
static int
evthread_notify_base_default(struct event_base *base)
{
	char buf[1];
	int r;
	buf[0] = (char) 0;
#ifdef WIN32
	r = send(base->th_notify_fd[1], buf, 1, 0);
#else
	r = write(base->th_notify_fd[1], buf, 1);
#endif
	return (r < 0 && errno != EAGAIN) ? -1 : 0;
}

#if defined(_EVENT_HAVE_EVENTFD) && defined(_EVENT_HAVE_SYS_EVENTFD_H)
/* Helper callback: wake an event_base from another thread.  This version
 * assumes that you have a working eventfd() implementation. */
static int
evthread_notify_base_eventfd(struct event_base *base)
{
	ev_uint64_t msg = 1;
	int r;
	do {
		r = write(base->th_notify_fd[0], (void*) &msg, sizeof(msg));
	} while (r < 0 && errno == EAGAIN);

	return (r < 0) ? -1 : 0;
}
#endif

/** Tell the thread currently running the event_loop for base (if any) that it
 * needs to stop waiting in its dispatch function (if it is) and process all
 * active events and deferred callbacks (if there are any).  */
static int
evthread_notify_base(struct event_base *base)
{
	EVENT_BASE_ASSERT_LOCKED(base);
	if (!base->th_notify_fn)
		return -1;
	if (base->is_notify_pending)
		return 0;
	base->is_notify_pending = 1;
	return base->th_notify_fn(base);
}

/* Implementation function to add an event.  Works just like event_add,
 * except: 1) it requires that we have the lock.  2) if tv_is_absolute is set,
 * we treat tv as an absolute time, not as an interval to add to the current
 * time */
static inline int
event_add_internal(struct event *ev, const struct timeval *tv,
    int tv_is_absolute)
{
	struct event_base *base = ev->ev_base;
	int res = 0;
	int notify = 0;

	EVENT_BASE_ASSERT_LOCKED(base);
	_event_debug_assert_is_setup(ev);

	event_debug((
		 "event_add: event: %p (fd %d), %s%s%scall %p",
		 ev,
		 (int)ev->ev_fd,
		 ev->ev_events & EV_READ ? "EV_READ " : " ",
		 ev->ev_events & EV_WRITE ? "EV_WRITE " : " ",
		 tv ? "EV_TIMEOUT " : " ",
		 ev->ev_callback));

	EVUTIL_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 the main thread is currently executing a signal event's
	 * callback, and we are not the main thread, then we want to wait
	 * until the callback is done before we mess with the event, or else
	 * we can race on ev_ncalls and ev_pncalls below. */
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
	if (base->current_event == ev && (ev->ev_events & EV_SIGNAL)
	    && !EVBASE_IN_THREAD(base)) {
		++base->current_event_waiters;
		EVTHREAD_COND_WAIT(base->current_event_cond, base->th_base_lock);
	}
#endif

	if ((ev->ev_events & (EV_READ|EV_WRITE|EV_SIGNAL)) &&
	    !(ev->ev_flags & (EVLIST_INSERTED|EVLIST_ACTIVE))) {
		if (ev->ev_events & (EV_READ|EV_WRITE))
			res = evmap_io_add(base, ev->ev_fd, ev);
		else if (ev->ev_events & EV_SIGNAL)
			res = evmap_signal_add(base, (int)ev->ev_fd, ev);
		if (res != -1)
			event_queue_insert(base, ev, EVLIST_INSERTED);
		if (res == 1) {
			/* evmap says we need to notify the main thread. */
			notify = 1;
			res = 0;
		}
	}

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

		/*
		 * for persistent timeout events, we remember the
		 * timeout value and re-add the event.
		 *
		 * If tv_is_absolute, this was already set.
		 */
		if (ev->ev_closure == EV_CLOSURE_PERSIST && !tv_is_absolute)
			ev->ev_io_timeout = *tv;

		/*
		 * we already reserved memory above for the case where we
		 * are not replacing an existing timeout.
		 */
		if (ev->ev_flags & EVLIST_TIMEOUT) {
			/* XXX I believe this is needless. */
			if (min_heap_elt_is_top(ev))
				notify = 1;
			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)) {
			if (ev->ev_events & EV_SIGNAL) {
				/* 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);

		common_timeout = is_common_timeout(tv, base);
		if (tv_is_absolute) {
			ev->ev_timeout = *tv;
		} else if (common_timeout) {
			struct timeval tmp = *tv;
			tmp.tv_usec &= MICROSECONDS_MASK;
			evutil_timeradd(&now, &tmp, &ev->ev_timeout);
			ev->ev_timeout.tv_usec |=
			    (tv->tv_usec & ~MICROSECONDS_MASK);
		} else {
			evutil_timeradd(&now, tv, &ev->ev_timeout);
		}

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

		event_queue_insert(base, ev, EVLIST_TIMEOUT);
		if (common_timeout) {
			struct common_timeout_list *ctl =
			    get_common_timeout_list(base, &ev->ev_timeout);
			if (ev == TAILQ_FIRST(&ctl->events)) {
				common_timeout_schedule(ctl, &now, ev);
			}
		} else {
			/* See if the earliest timeout is now earlier than it
			 * was before: if so, we will need to tell the main
			 * thread to wake up earlier than it would
			 * otherwise. */
			if (min_heap_elt_is_top(ev))
				notify = 1;
		}
	}

	/* if we are not in the right thread, we need to wake up the loop */
	if (res != -1 && notify && EVBASE_NEED_NOTIFY(base))
		evthread_notify_base(base);

	_event_debug_note_add(ev);

	return (res);
}

int
event_del(struct event *ev)
{
	int res;

	if (EVUTIL_FAILURE_CHECK(!ev->ev_base)) {
		event_warnx("%s: event has no event_base set.", __func__);
		return -1;
	}

	EVBASE_ACQUIRE_LOCK(ev->ev_base, th_base_lock);

	res = event_del_internal(ev);

	EVBASE_RELEASE_LOCK(ev->ev_base, th_base_lock);

	return (res);
}

/* Helper for event_del: always called with th_base_lock held. */
static inline int
event_del_internal(struct event *ev)
{
	struct event_base *base;
	int res = 0, notify = 0;

	event_debug(("event_del: %p (fd %d), callback %p",
		ev, (int)ev->ev_fd, ev->ev_callback));

	/* An event without a base has not been added */
	if (ev->ev_base == NULL)
		return (-1);

	EVENT_BASE_ASSERT_LOCKED(ev->ev_base);

	/* If the main thread is currently executing this event's callback,
	 * and we are not the main thread, then we want to wait until the
	 * callback is done before we start removing the event.  That way,
	 * when this function returns, it will be safe to free the
	 * user-supplied argument. */
	base = ev->ev_base;
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
	if (base->current_event == ev && !EVBASE_IN_THREAD(base)) {
		++base->current_event_waiters;
		EVTHREAD_COND_WAIT(base->current_event_cond, base->th_base_lock);
	}
#endif

	EVUTIL_ASSERT(!(ev->ev_flags & ~EVLIST_ALL));

	/* See if we are just active executing this event in a loop */
	if (ev->ev_events & EV_SIGNAL) {
		if (ev->ev_ncalls && ev->ev_pncalls) {
			/* Abort loop */
			*ev->ev_pncalls = 0;
		}
	}

	if (ev->ev_flags & EVLIST_TIMEOUT) {
		/* NOTE: We never need to notify the main thread because of a
		 * deleted timeout event: all that could happen if we don't is
		 * that the dispatch loop might wake up too early.  But the
		 * point of notifying the main thread _is_ to wake up the
		 * dispatch loop early anyway, so we wouldn't gain anything by
		 * doing it.
		 */
		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);
		if (ev->ev_events & (EV_READ|EV_WRITE))
			res = evmap_io_del(base, ev->ev_fd, ev);
		else
			res = evmap_signal_del(base, (int)ev->ev_fd, ev);
		if (res == 1) {
			/* evmap says we need to notify the main thread. */
			notify = 1;
			res = 0;
		}
	}

	/* if we are not in the right thread, we need to wake up the loop */
	if (res != -1 && notify && EVBASE_NEED_NOTIFY(base))
		evthread_notify_base(base);

	_event_debug_note_del(ev);

	return (res);
}

void
event_active(struct event *ev, int res, short ncalls)
{
	if (EVUTIL_FAILURE_CHECK(!ev->ev_base)) {
		event_warnx("%s: event has no event_base set.", __func__);
		return;
	}

	EVBASE_ACQUIRE_LOCK(ev->ev_base, th_base_lock);

	_event_debug_assert_is_setup(ev);

	event_active_nolock(ev, res, ncalls);

	EVBASE_RELEASE_LOCK(ev->ev_base, th_base_lock);
}


void
event_active_nolock(struct event *ev, int res, short ncalls)
{
	struct event_base *base;

	event_debug(("event_active: %p (fd %d), res %d, callback %p",
		ev, (int)ev->ev_fd, (int)res, ev->ev_callback));


	/* We get different kinds of events, add them together */
	if (ev->ev_flags & EVLIST_ACTIVE) {
		ev->ev_res |= res;
		return;
	}

	base = ev->ev_base;

	EVENT_BASE_ASSERT_LOCKED(base);

	ev->ev_res = res;

	if (ev->ev_pri < base->event_running_priority)
		base->event_continue = 1;

	if (ev->ev_events & EV_SIGNAL) {
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
		if (base->current_event == ev && !EVBASE_IN_THREAD(base)) {
			++base->current_event_waiters;
			EVTHREAD_COND_WAIT(base->current_event_cond, base->th_base_lock);
		}
#endif
		ev->ev_ncalls = ncalls;
		ev->ev_pncalls = NULL;
	}

	event_queue_insert(base, ev, EVLIST_ACTIVE);

	if (EVBASE_NEED_NOTIFY(base))
		evthread_notify_base(base);
}

void
event_deferred_cb_init(struct deferred_cb *cb, deferred_cb_fn fn, void *arg)
{
	memset(cb, 0, sizeof(struct deferred_cb));
	cb->cb = fn;
	cb->arg = arg;
}

void
event_deferred_cb_cancel(struct deferred_cb_queue *queue,
    struct deferred_cb *cb)
{
	if (!queue) {
		if (current_base)
			queue = &current_base->defer_queue;
		else
			return;
	}

	LOCK_DEFERRED_QUEUE(queue);
	if (cb->queued) {
		TAILQ_REMOVE(&queue->deferred_cb_list, cb, cb_next);
		--queue->active_count;
		cb->queued = 0;
	}
	UNLOCK_DEFERRED_QUEUE(queue);
}

void
event_deferred_cb_schedule(struct deferred_cb_queue *queue,
    struct deferred_cb *cb)
{
	if (!queue) {
		if (current_base)
			queue = &current_base->defer_queue;
		else
			return;
	}

	LOCK_DEFERRED_QUEUE(queue);
	if (!cb->queued) {
		cb->queued = 1;
		TAILQ_INSERT_TAIL(&queue->deferred_cb_list, cb, cb_next);
		++queue->active_count;
		if (queue->notify_fn)
			queue->notify_fn(queue, queue->notify_arg);
	}
	UNLOCK_DEFERRED_QUEUE(queue);
}

static int
timeout_next(struct event_base *base, struct timeval **tv_p)
{
	/* Caller must hold th_base_lock */
	struct timeval now;
	struct event *ev;
	struct timeval *tv = *tv_p;
	int res = 0;

	ev = min_heap_top(&base->timeheap);

	if (ev == NULL) {
		/* if no time-based events are active wait for I/O */
		*tv_p = NULL;
		goto out;
	}

	if (gettime(base, &now) == -1) {
		res = -1;
		goto out;
	}

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

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

	EVUTIL_ASSERT(tv->tv_sec >= 0);
	EVUTIL_ASSERT(tv->tv_usec >= 0);
	event_debug(("timeout_next: in %d seconds", (int)tv->tv_sec));

out:
	return (res);
}

/*
 * Determines if the time is running backwards by comparing the current time
 * against the last time we checked.  Not needed when using clock monotonic.
 * If time is running backwards, we adjust the firing time of every event by
 * the amount that time seems to have jumped.
 */
static void
timeout_correct(struct event_base *base, struct timeval *tv)
{
	/* Caller must hold th_base_lock. */
	struct event **pev;
	unsigned int size;
	struct timeval off;
	int i;

	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 minheap property, because we change every element.
	 */
	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);
	}
	for (i=0; i<base->n_common_timeouts; ++i) {
		struct event *ev;
		struct common_timeout_list *ctl =
		    base->common_timeout_queues[i];
		TAILQ_FOREACH(ev, &ctl->events,
		    ev_timeout_pos.ev_next_with_common_timeout) {
			struct timeval *ev_tv = &ev->ev_timeout;
			ev_tv->tv_usec &= MICROSECONDS_MASK;
			evutil_timersub(ev_tv, &off, ev_tv);
			ev_tv->tv_usec |= COMMON_TIMEOUT_MAGIC |
			    (i<<COMMON_TIMEOUT_IDX_SHIFT);
		}
	}

	/* Now remember what the new time turned out to be. */
	base->event_tv = *tv;
}

/* Activate every event whose timeout has elapsed. */
static void
timeout_process(struct event_base *base)
{
	/* Caller must hold lock. */
	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_internal(ev);

		event_debug(("timeout_process: call %p",
			 ev->ev_callback));
		event_active_nolock(ev, EV_TIMEOUT, 1);
	}
}

/* Remove 'ev' from 'queue' (EVLIST_...) in base. */
static void
event_queue_remove(struct event_base *base, struct event *ev, int queue)
{
	EVENT_BASE_ASSERT_LOCKED(base);

	if (!(ev->ev_flags & queue)) {
		event_errx(1, "%s: %p(fd %d) not on queue %x", __func__,
			   ev, ev->ev_fd, queue);
		return;
	}

	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:
		if (is_common_timeout(&ev->ev_timeout, base)) {
			struct common_timeout_list *ctl =
			    get_common_timeout_list(base, &ev->ev_timeout);
			TAILQ_REMOVE(&ctl->events, ev,
			    ev_timeout_pos.ev_next_with_common_timeout);
		} else {
			min_heap_erase(&base->timeheap, ev);
		}
		break;
	default:
		event_errx(1, "%s: unknown queue %x", __func__, queue);
	}
}

/* Add 'ev' to the common timeout list in 'ev'. */
static void
insert_common_timeout_inorder(struct common_timeout_list *ctl,
    struct event *ev)
{
	struct event *e;
	/* By all logic, we should just be able to append 'ev' to the end of
	 * ctl->events, since the timeout on each 'ev' is set to {the common
	 * timeout} + {the time when we add the event}, and so the events
	 * should arrive in order of their timeeouts.  But just in case
	 * there's some wacky threading issue going on, we do a search from
	 * the end of 'ev' to find the right insertion point.
	 */
	TAILQ_FOREACH_REVERSE(e, &ctl->events,
	    event_list, ev_timeout_pos.ev_next_with_common_timeout) {
		/* This timercmp is a little sneaky, since both ev and e have
		 * magic values in tv_usec.  Fortunately, they ought to have
		 * the _same_ magic values in tv_usec.  Let's assert for that.
		 */
		EVUTIL_ASSERT(
			is_same_common_timeout(&e->ev_timeout, &ev->ev_timeout));
		if (evutil_timercmp(&ev->ev_timeout, &e->ev_timeout, >=)) {
			TAILQ_INSERT_AFTER(&ctl->events, e, ev,
			    ev_timeout_pos.ev_next_with_common_timeout);
			return;
		}
	}
	TAILQ_INSERT_HEAD(&ctl->events, ev,
	    ev_timeout_pos.ev_next_with_common_timeout);
}

static void
event_queue_insert(struct event_base *base, struct event *ev, int queue)
{
	EVENT_BASE_ASSERT_LOCKED(base);

	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);
		return;
	}

	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: {
		if (is_common_timeout(&ev->ev_timeout, base)) {
			struct common_timeout_list *ctl =
			    get_common_timeout_list(base, &ev->ev_timeout);
			insert_common_timeout_inorder(ctl, ev);
		} else
			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 (_EVENT_VERSION);
}

ev_uint32_t
event_get_version_number(void)
{
	return (_EVENT_NUMERIC_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);
}

#ifndef _EVENT_DISABLE_MM_REPLACEMENT
static void *(*_mm_malloc_fn)(size_t sz) = NULL;
static void *(*_mm_realloc_fn)(void *p, size_t sz) = NULL;
static void (*_mm_free_fn)(void *p) = NULL;

void *
event_mm_malloc_(size_t sz)
{
	if (_mm_malloc_fn)
		return _mm_malloc_fn(sz);
	else
		return malloc(sz);
}

void *
event_mm_calloc_(size_t count, size_t size)
{
	if (_mm_malloc_fn) {
		size_t sz = count * size;
		void *p = _mm_malloc_fn(sz);
		if (p)
			memset(p, 0, sz);
		return p;
	} else
		return calloc(count, size);
}

char *
event_mm_strdup_(const char *str)
{
	if (_mm_malloc_fn) {
		size_t ln = strlen(str);
		void *p = _mm_malloc_fn(ln+1);
		if (p)
			memcpy(p, str, ln+1);
		return p;
	} else
#ifdef WIN32
		return _strdup(str);
#else
		return strdup(str);
#endif
}

void *
event_mm_realloc_(void *ptr, size_t sz)
{
	if (_mm_realloc_fn)
		return _mm_realloc_fn(ptr, sz);
	else
		return realloc(ptr, sz);
}

void
event_mm_free_(void *ptr)
{
	if (_mm_free_fn)
		_mm_free_fn(ptr);
	else
		free(ptr);
}

void
event_set_mem_functions(void *(*malloc_fn)(size_t sz),
			void *(*realloc_fn)(void *ptr, size_t sz),
			void (*free_fn)(void *ptr))
{
	_mm_malloc_fn = malloc_fn;
	_mm_realloc_fn = realloc_fn;
	_mm_free_fn = free_fn;
}
#endif

#if defined(_EVENT_HAVE_EVENTFD) && defined(_EVENT_HAVE_SYS_EVENTFD_H)
static void
evthread_notify_drain_eventfd(evutil_socket_t fd, short what, void *arg)
{
	ev_uint64_t msg;
	ev_ssize_t r;
	struct event_base *base = arg;

	r = read(fd, (void*) &msg, sizeof(msg));
	if (r<0 && errno != EAGAIN) {
		event_sock_warn(fd, "Error reading from eventfd");
	}
	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	base->is_notify_pending = 0;
	EVBASE_RELEASE_LOCK(base, th_base_lock);
}
#endif

static void
evthread_notify_drain_default(evutil_socket_t fd, short what, void *arg)
{
	unsigned char buf[1024];
	struct event_base *base = arg;
#ifdef WIN32
	while (recv(fd, (char*)buf, sizeof(buf), 0) > 0)
		;
#else
	while (read(fd, (char*)buf, sizeof(buf)) > 0)
		;
#endif

	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	base->is_notify_pending = 0;
	EVBASE_RELEASE_LOCK(base, th_base_lock);
}

int
evthread_make_base_notifiable(struct event_base *base)
{
	void (*cb)(evutil_socket_t, short, void *) = evthread_notify_drain_default;
	int (*notify)(struct event_base *) = evthread_notify_base_default;

	/* XXXX grab the lock here? */
	if (!base)
		return -1;

	if (base->th_notify_fd[0] >= 0)
		return 0;

#if defined(_EVENT_HAVE_EVENTFD) && defined(_EVENT_HAVE_SYS_EVENTFD_H)
#ifndef EFD_CLOEXEC
#define EFD_CLOEXEC 0
#endif
	base->th_notify_fd[0] = eventfd(0, EFD_CLOEXEC);
	if (base->th_notify_fd[0] >= 0) {
		evutil_make_socket_closeonexec(base->th_notify_fd[0]);
		notify = evthread_notify_base_eventfd;
		cb = evthread_notify_drain_eventfd;
	}
#endif
#if defined(_EVENT_HAVE_PIPE)
	if (base->th_notify_fd[0] < 0) {
		if ((base->evsel->features & EV_FEATURE_FDS)) {
			if (pipe(base->th_notify_fd) < 0) {
				event_warn("%s: pipe", __func__);
			} else {
				evutil_make_socket_closeonexec(base->th_notify_fd[0]);
				evutil_make_socket_closeonexec(base->th_notify_fd[1]);
			}
		}
	}
#endif

#ifdef WIN32
#define LOCAL_SOCKETPAIR_AF AF_INET
#else
#define LOCAL_SOCKETPAIR_AF AF_UNIX
#endif
	if (base->th_notify_fd[0] < 0) {
		if (evutil_socketpair(LOCAL_SOCKETPAIR_AF, SOCK_STREAM, 0,
			base->th_notify_fd) == -1) {
			event_sock_warn(-1, "%s: socketpair", __func__);
			return (-1);
		} else {
			evutil_make_socket_closeonexec(base->th_notify_fd[0]);
			evutil_make_socket_closeonexec(base->th_notify_fd[1]);
		}
	}

	evutil_make_socket_nonblocking(base->th_notify_fd[0]);

	base->th_notify_fn = notify;

	/*
	  Making the second socket nonblocking is a bit subtle, given that we
	  ignore any EAGAIN returns when writing to it, and you don't usally
	  do that for a nonblocking socket. But if the kernel gives us EAGAIN,
	  then there's no need to add any more data to the buffer, since
	  the main thread is already either about to wake up and drain it,
	  or woken up and in the process of draining it.
	*/
	if (base->th_notify_fd[1] > 0)
		evutil_make_socket_nonblocking(base->th_notify_fd[1]);

	/* prepare an event that we can use for wakeup */
	event_assign(&base->th_notify, base, base->th_notify_fd[0],
				 EV_READ|EV_PERSIST, cb, base);

	/* we need to mark this as internal event */
	base->th_notify.ev_flags |= EVLIST_INTERNAL;
	event_priority_set(&base->th_notify, 0);

	return event_add(&base->th_notify, NULL);
}

void
event_base_dump_events(struct event_base *base, FILE *output)
{
	struct event *e;
	int i;
	fprintf(output, "Inserted events:\n");
	TAILQ_FOREACH(e, &base->eventqueue, ev_next) {
		fprintf(output, "  %p [fd %ld]%s%s%s%s%s\n",
				(void*)e, (long)e->ev_fd,
				(e->ev_events&EV_READ)?" Read":"",
				(e->ev_events&EV_WRITE)?" Write":"",
				(e->ev_events&EV_SIGNAL)?" Signal":"",
				(e->ev_events&EV_TIMEOUT)?" Timeout":"",
				(e->ev_events&EV_PERSIST)?" Persist":"");

	}
	for (i = 0; i < base->nactivequeues; ++i) {
		if (TAILQ_EMPTY(&base->activequeues[i]))
			continue;
		fprintf(output, "Active events [priority %d]:\n", i);
		TAILQ_FOREACH(e, &base->eventqueue, ev_next) {
			fprintf(output, "  %p [fd %ld]%s%s%s%s\n",
					(void*)e, (long)e->ev_fd,
					(e->ev_res&EV_READ)?" Read active":"",
					(e->ev_res&EV_WRITE)?" Write active":"",
					(e->ev_res&EV_SIGNAL)?" Signal active":"",
					(e->ev_res&EV_TIMEOUT)?" Timeout active":"");
		}
	}
}

void
event_base_add_virtual(struct event_base *base)
{
	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	base->virtual_event_count++;
	EVBASE_RELEASE_LOCK(base, th_base_lock);
}

void
event_base_del_virtual(struct event_base *base)
{
	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	EVUTIL_ASSERT(base->virtual_event_count > 0);
	base->virtual_event_count--;
	if (base->virtual_event_count == 0 && EVBASE_NEED_NOTIFY(base))
		evthread_notify_base(base);
	EVBASE_RELEASE_LOCK(base, th_base_lock);
}

#ifndef _EVENT_DISABLE_THREAD_SUPPORT
int
event_global_setup_locks_(const int enable_locks)
{
#ifndef _EVENT_DISABLE_DEBUG_MODE
	EVTHREAD_SETUP_GLOBAL_LOCK(_event_debug_map_lock, 0);
#endif
	if (evsig_global_setup_locks_(enable_locks) < 0)
		return -1;
	if (evutil_secure_rng_global_setup_locks_(enable_locks) < 0)
		return -1;
	return 0;
}
#endif

void
event_base_assert_ok(struct event_base *base)
{
	int i;
	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
	evmap_check_integrity(base);

	/* Check the heap property */
	for (i = 1; i < (int)base->timeheap.n; ++i) {
		int parent = (i - 1) / 2;
		struct event *ev, *p_ev;
		ev = base->timeheap.p[i];
		p_ev = base->timeheap.p[parent];
		EVUTIL_ASSERT(ev->ev_flags & EV_TIMEOUT);
		EVUTIL_ASSERT(evutil_timercmp(&p_ev->ev_timeout, &ev->ev_timeout, <=));
		EVUTIL_ASSERT(ev->ev_timeout_pos.min_heap_idx == i);
	}

	/* Check that the common timeouts are fine */
	for (i = 0; i < base->n_common_timeouts; ++i) {
		struct common_timeout_list *ctl = base->common_timeout_queues[i];
		struct event *last=NULL, *ev;
		TAILQ_FOREACH(ev, &ctl->events, ev_timeout_pos.ev_next_with_common_timeout) {
			if (last)
				EVUTIL_ASSERT(evutil_timercmp(&last->ev_timeout, &ev->ev_timeout, <=));
			EVUTIL_ASSERT(ev->ev_flags & EV_TIMEOUT);
			EVUTIL_ASSERT(is_common_timeout(&ev->ev_timeout,base));
			EVUTIL_ASSERT(COMMON_TIMEOUT_IDX(&ev->ev_timeout) == i);
			last = ev;
		}
	}

	EVBASE_RELEASE_LOCK(base, th_base_lock);
}