minix/external/bsd/libevent/dist/evthread.c
David van Moolenbroek e985b92992 Import libevent
Change-Id: Ic75f4cac5eb07ffaba8f97d10673d7d7e2b1762d
2014-10-03 10:00:53 +00:00

448 lines
12 KiB
C

/* $NetBSD: evthread.c,v 1.1.1.1 2013/04/11 16:43:25 christos Exp $ */
/*
* Copyright (c) 2008-2012 Niels Provos, Nick Mathewson
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "event2/event-config.h"
#include <sys/cdefs.h>
__RCSID("$NetBSD: evthread.c,v 1.1.1.1 2013/04/11 16:43:25 christos Exp $");
#ifndef _EVENT_DISABLE_THREAD_SUPPORT
#include "event2/thread.h"
#include <stdlib.h>
#include <string.h>
#include "log-internal.h"
#include "mm-internal.h"
#include "util-internal.h"
#include "evthread-internal.h"
#ifdef EVTHREAD_EXPOSE_STRUCTS
#define GLOBAL
#else
#define GLOBAL static
#endif
/* globals */
GLOBAL int _evthread_lock_debugging_enabled = 0;
GLOBAL struct evthread_lock_callbacks _evthread_lock_fns = {
0, 0, NULL, NULL, NULL, NULL
};
GLOBAL unsigned long (*_evthread_id_fn)(void) = NULL;
GLOBAL struct evthread_condition_callbacks _evthread_cond_fns = {
0, NULL, NULL, NULL, NULL
};
/* Used for debugging */
static struct evthread_lock_callbacks _original_lock_fns = {
0, 0, NULL, NULL, NULL, NULL
};
static struct evthread_condition_callbacks _original_cond_fns = {
0, NULL, NULL, NULL, NULL
};
void
evthread_set_id_callback(unsigned long (*id_fn)(void))
{
_evthread_id_fn = id_fn;
}
int
evthread_set_lock_callbacks(const struct evthread_lock_callbacks *cbs)
{
struct evthread_lock_callbacks *target =
_evthread_lock_debugging_enabled
? &_original_lock_fns : &_evthread_lock_fns;
if (!cbs) {
if (target->alloc)
event_warnx("Trying to disable lock functions after "
"they have been set up will probaby not work.");
memset(target, 0, sizeof(_evthread_lock_fns));
return 0;
}
if (target->alloc) {
/* Uh oh; we already had locking callbacks set up.*/
if (target->lock_api_version == cbs->lock_api_version &&
target->supported_locktypes == cbs->supported_locktypes &&
target->alloc == cbs->alloc &&
target->free == cbs->free &&
target->lock == cbs->lock &&
target->unlock == cbs->unlock) {
/* no change -- allow this. */
return 0;
}
event_warnx("Can't change lock callbacks once they have been "
"initialized.");
return -1;
}
if (cbs->alloc && cbs->free && cbs->lock && cbs->unlock) {
memcpy(target, cbs, sizeof(_evthread_lock_fns));
return event_global_setup_locks_(1);
} else {
return -1;
}
}
int
evthread_set_condition_callbacks(const struct evthread_condition_callbacks *cbs)
{
struct evthread_condition_callbacks *target =
_evthread_lock_debugging_enabled
? &_original_cond_fns : &_evthread_cond_fns;
if (!cbs) {
if (target->alloc_condition)
event_warnx("Trying to disable condition functions "
"after they have been set up will probaby not "
"work.");
memset(target, 0, sizeof(_evthread_cond_fns));
return 0;
}
if (target->alloc_condition) {
/* Uh oh; we already had condition callbacks set up.*/
if (target->condition_api_version == cbs->condition_api_version &&
target->alloc_condition == cbs->alloc_condition &&
target->free_condition == cbs->free_condition &&
target->signal_condition == cbs->signal_condition &&
target->wait_condition == cbs->wait_condition) {
/* no change -- allow this. */
return 0;
}
event_warnx("Can't change condition callbacks once they "
"have been initialized.");
return -1;
}
if (cbs->alloc_condition && cbs->free_condition &&
cbs->signal_condition && cbs->wait_condition) {
memcpy(target, cbs, sizeof(_evthread_cond_fns));
}
if (_evthread_lock_debugging_enabled) {
_evthread_cond_fns.alloc_condition = cbs->alloc_condition;
_evthread_cond_fns.free_condition = cbs->free_condition;
_evthread_cond_fns.signal_condition = cbs->signal_condition;
}
return 0;
}
struct debug_lock {
unsigned locktype;
unsigned long held_by;
/* XXXX if we ever use read-write locks, we will need a separate
* lock to protect count. */
int count;
void *lock;
};
static void *
debug_lock_alloc(unsigned locktype)
{
struct debug_lock *result = mm_malloc(sizeof(struct debug_lock));
if (!result)
return NULL;
if (_original_lock_fns.alloc) {
if (!(result->lock = _original_lock_fns.alloc(
locktype|EVTHREAD_LOCKTYPE_RECURSIVE))) {
mm_free(result);
return NULL;
}
} else {
result->lock = NULL;
}
result->locktype = locktype;
result->count = 0;
result->held_by = 0;
return result;
}
static void
debug_lock_free(void *lock_, unsigned locktype)
{
struct debug_lock *lock = lock_;
EVUTIL_ASSERT(lock->count == 0);
EVUTIL_ASSERT(locktype == lock->locktype);
if (_original_lock_fns.free) {
_original_lock_fns.free(lock->lock,
lock->locktype|EVTHREAD_LOCKTYPE_RECURSIVE);
}
lock->lock = NULL;
lock->count = -100;
mm_free(lock);
}
static void
evthread_debug_lock_mark_locked(unsigned mode, struct debug_lock *lock)
{
++lock->count;
if (!(lock->locktype & EVTHREAD_LOCKTYPE_RECURSIVE))
EVUTIL_ASSERT(lock->count == 1);
if (_evthread_id_fn) {
unsigned long me;
me = _evthread_id_fn();
if (lock->count > 1)
EVUTIL_ASSERT(lock->held_by == me);
lock->held_by = me;
}
}
static int
debug_lock_lock(unsigned mode, void *lock_)
{
struct debug_lock *lock = lock_;
int res = 0;
if (lock->locktype & EVTHREAD_LOCKTYPE_READWRITE)
EVUTIL_ASSERT(mode & (EVTHREAD_READ|EVTHREAD_WRITE));
else
EVUTIL_ASSERT((mode & (EVTHREAD_READ|EVTHREAD_WRITE)) == 0);
if (_original_lock_fns.lock)
res = _original_lock_fns.lock(mode, lock->lock);
if (!res) {
evthread_debug_lock_mark_locked(mode, lock);
}
return res;
}
static void
evthread_debug_lock_mark_unlocked(unsigned mode, struct debug_lock *lock)
{
if (lock->locktype & EVTHREAD_LOCKTYPE_READWRITE)
EVUTIL_ASSERT(mode & (EVTHREAD_READ|EVTHREAD_WRITE));
else
EVUTIL_ASSERT((mode & (EVTHREAD_READ|EVTHREAD_WRITE)) == 0);
if (_evthread_id_fn) {
EVUTIL_ASSERT(lock->held_by == _evthread_id_fn());
if (lock->count == 1)
lock->held_by = 0;
}
--lock->count;
EVUTIL_ASSERT(lock->count >= 0);
}
static int
debug_lock_unlock(unsigned mode, void *lock_)
{
struct debug_lock *lock = lock_;
int res = 0;
evthread_debug_lock_mark_unlocked(mode, lock);
if (_original_lock_fns.unlock)
res = _original_lock_fns.unlock(mode, lock->lock);
return res;
}
static int
debug_cond_wait(void *_cond, void *_lock, const struct timeval *tv)
{
int r;
struct debug_lock *lock = _lock;
EVUTIL_ASSERT(lock);
EVLOCK_ASSERT_LOCKED(_lock);
evthread_debug_lock_mark_unlocked(0, lock);
r = _original_cond_fns.wait_condition(_cond, lock->lock, tv);
evthread_debug_lock_mark_locked(0, lock);
return r;
}
void
evthread_enable_lock_debuging(void)
{
struct evthread_lock_callbacks cbs = {
EVTHREAD_LOCK_API_VERSION,
EVTHREAD_LOCKTYPE_RECURSIVE,
debug_lock_alloc,
debug_lock_free,
debug_lock_lock,
debug_lock_unlock
};
if (_evthread_lock_debugging_enabled)
return;
memcpy(&_original_lock_fns, &_evthread_lock_fns,
sizeof(struct evthread_lock_callbacks));
memcpy(&_evthread_lock_fns, &cbs,
sizeof(struct evthread_lock_callbacks));
memcpy(&_original_cond_fns, &_evthread_cond_fns,
sizeof(struct evthread_condition_callbacks));
_evthread_cond_fns.wait_condition = debug_cond_wait;
_evthread_lock_debugging_enabled = 1;
/* XXX return value should get checked. */
event_global_setup_locks_(0);
}
int
_evthread_is_debug_lock_held(void *lock_)
{
struct debug_lock *lock = lock_;
if (! lock->count)
return 0;
if (_evthread_id_fn) {
unsigned long me = _evthread_id_fn();
if (lock->held_by != me)
return 0;
}
return 1;
}
void *
_evthread_debug_get_real_lock(void *lock_)
{
struct debug_lock *lock = lock_;
return lock->lock;
}
void *
evthread_setup_global_lock_(void *lock_, unsigned locktype, int enable_locks)
{
/* there are four cases here:
1) we're turning on debugging; locking is not on.
2) we're turning on debugging; locking is on.
3) we're turning on locking; debugging is not on.
4) we're turning on locking; debugging is on. */
if (!enable_locks && _original_lock_fns.alloc == NULL) {
/* Case 1: allocate a debug lock. */
EVUTIL_ASSERT(lock_ == NULL);
return debug_lock_alloc(locktype);
} else if (!enable_locks && _original_lock_fns.alloc != NULL) {
/* Case 2: wrap the lock in a debug lock. */
struct debug_lock *lock;
EVUTIL_ASSERT(lock_ != NULL);
if (!(locktype & EVTHREAD_LOCKTYPE_RECURSIVE)) {
/* We can't wrap it: We need a recursive lock */
_original_lock_fns.free(lock_, locktype);
return debug_lock_alloc(locktype);
}
lock = mm_malloc(sizeof(struct debug_lock));
if (!lock) {
_original_lock_fns.free(lock_, locktype);
return NULL;
}
lock->lock = lock_;
lock->locktype = locktype;
lock->count = 0;
lock->held_by = 0;
return lock;
} else if (enable_locks && ! _evthread_lock_debugging_enabled) {
/* Case 3: allocate a regular lock */
EVUTIL_ASSERT(lock_ == NULL);
return _evthread_lock_fns.alloc(locktype);
} else {
/* Case 4: Fill in a debug lock with a real lock */
struct debug_lock *lock = lock_;
EVUTIL_ASSERT(enable_locks &&
_evthread_lock_debugging_enabled);
EVUTIL_ASSERT(lock->locktype == locktype);
EVUTIL_ASSERT(lock->lock == NULL);
lock->lock = _original_lock_fns.alloc(
locktype|EVTHREAD_LOCKTYPE_RECURSIVE);
if (!lock->lock) {
lock->count = -200;
mm_free(lock);
return NULL;
}
return lock;
}
}
#ifndef EVTHREAD_EXPOSE_STRUCTS
unsigned long
_evthreadimpl_get_id()
{
return _evthread_id_fn ? _evthread_id_fn() : 1;
}
void *
_evthreadimpl_lock_alloc(unsigned locktype)
{
return _evthread_lock_fns.alloc ?
_evthread_lock_fns.alloc(locktype) : NULL;
}
void
_evthreadimpl_lock_free(void *lock, unsigned locktype)
{
if (_evthread_lock_fns.free)
_evthread_lock_fns.free(lock, locktype);
}
int
_evthreadimpl_lock_lock(unsigned mode, void *lock)
{
if (_evthread_lock_fns.lock)
return _evthread_lock_fns.lock(mode, lock);
else
return 0;
}
int
_evthreadimpl_lock_unlock(unsigned mode, void *lock)
{
if (_evthread_lock_fns.unlock)
return _evthread_lock_fns.unlock(mode, lock);
else
return 0;
}
void *
_evthreadimpl_cond_alloc(unsigned condtype)
{
return _evthread_cond_fns.alloc_condition ?
_evthread_cond_fns.alloc_condition(condtype) : NULL;
}
void
_evthreadimpl_cond_free(void *cond)
{
if (_evthread_cond_fns.free_condition)
_evthread_cond_fns.free_condition(cond);
}
int
_evthreadimpl_cond_signal(void *cond, int broadcast)
{
if (_evthread_cond_fns.signal_condition)
return _evthread_cond_fns.signal_condition(cond, broadcast);
else
return 0;
}
int
_evthreadimpl_cond_wait(void *cond, void *lock, const struct timeval *tv)
{
if (_evthread_cond_fns.wait_condition)
return _evthread_cond_fns.wait_condition(cond, lock, tv);
else
return 0;
}
int
_evthreadimpl_is_lock_debugging_enabled(void)
{
return _evthread_lock_debugging_enabled;
}
int
_evthreadimpl_locking_enabled(void)
{
return _evthread_lock_fns.lock != NULL;
}
#endif
#endif