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/*
* Copyright (c) 2008-2010 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 "event-config.h"
#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"
/* globals */
int _evthread_lock_debugging_enabled = 0;
struct evthread_lock_callbacks _evthread_lock_fns = {
0, 0, NULL, NULL, NULL, NULL
};
/* Used for debugging */
static struct evthread_lock_callbacks _original_lock_fns = {
0, 0, NULL, NULL, NULL, NULL
};
unsigned long (*_evthread_id_fn)(void) = 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) {
memset(target, 0, sizeof(_evthread_lock_fns));
return 0;
}
if (cbs->alloc && cbs->free && cbs->lock && cbs->unlock) {
memcpy(target, cbs, sizeof(_evthread_lock_fns));
return 0;
} else {
return -1;
}
}
static void
api_error(void)
{
event_errx(1, "evthread_set_locking_callback and "
"evthread_set_lock_create_callbacks are obsolete; use "
"evthread_set_lock_callbacks instead.");
}
void
evthread_set_locking_callback(void (*locking_fn)(int mode, void *lock))
{
api_error();
}
void
evthread_set_lock_create_callbacks(void *(*alloc_fn)(void),
void (*free_fn)(void *))
{
api_error();
}
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 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) {
++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;
}
}
return res;
}
static int
debug_lock_unlock(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 (_evthread_id_fn) {
unsigned long me = _evthread_id_fn();
EVUTIL_ASSERT(lock->held_by == me);
if (lock->count == 1)
lock->held_by = 0;
}
--lock->count;
EVUTIL_ASSERT(lock->count >= 0);
if (_original_lock_fns.unlock)
res = _original_lock_fns.unlock(mode, lock->lock);
return res;
}
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));
_evthread_lock_debugging_enabled = 1;
}
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;
}
#endif
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