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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2009-2010. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
/*
* Author: Rickard Green
*/
#define ETHR_INLINE_FUNC_NAME_(X) X ## __
#define ETHR_EVENT_IMPL__
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "ethread.h"
#if defined(ETHR_LINUX_FUTEX_IMPL__)
/* --- Linux futex implementation of ethread events ------------------------- */
#include <sched.h>
#include <errno.h>
#define ETHR_YIELD_AFTER_BUSY_LOOPS 50
int
ethr_event_init(ethr_event *e)
{
ethr_atomic_init(&e->futex, ETHR_EVENT_OFF__);
return 0;
}
int
ethr_event_destroy(ethr_event *e)
{
return 0;
}
static ETHR_INLINE int
wait__(ethr_event *e, int spincount)
{
unsigned sc = spincount;
int res;
ethr_sint_t val;
int until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS;
if (spincount < 0)
ETHR_FATAL_ERROR__(EINVAL);
while (1) {
while (1) {
val = ethr_atomic_read(&e->futex);
if (val == ETHR_EVENT_ON__)
return 0;
if (sc == 0)
break;
sc--;
ETHR_SPIN_BODY;
if (--until_yield == 0) {
until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS;
res = ETHR_YIELD();
if (res != 0)
ETHR_FATAL_ERROR__(res);
}
}
if (val != ETHR_EVENT_OFF_WAITER__) {
val = ethr_atomic_cmpxchg(&e->futex,
ETHR_EVENT_OFF_WAITER__,
ETHR_EVENT_OFF__);
if (val == ETHR_EVENT_ON__)
return 0;
ETHR_ASSERT(val == ETHR_EVENT_OFF__);
}
res = ETHR_FUTEX__(&e->futex, ETHR_FUTEX_WAIT__, ETHR_EVENT_OFF_WAITER__);
if (res == EINTR)
break;
if (res != 0 && res != EWOULDBLOCK)
ETHR_FATAL_ERROR__(res);
}
return res;
}
#elif defined(ETHR_PTHREADS)
/* --- Posix mutex/cond implementation of events ---------------------------- */
int
ethr_event_init(ethr_event *e)
{
int res;
ethr_atomic_init(&e->state, ETHR_EVENT_OFF__);
res = pthread_mutex_init(&e->mtx, NULL);
if (res != 0)
return res;
res = pthread_cond_init(&e->cnd, NULL);
if (res != 0) {
pthread_mutex_destroy(&e->mtx);
return res;
}
return 0;
}
int
ethr_event_destroy(ethr_event *e)
{
int res;
res = pthread_mutex_destroy(&e->mtx);
if (res != 0)
return res;
res = pthread_cond_destroy(&e->cnd);
if (res != 0)
return res;
return 0;
}
static ETHR_INLINE int
wait__(ethr_event *e, int spincount)
{
int sc = spincount;
ethr_sint_t val;
int res, ulres;
int until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS;
if (spincount < 0)
ETHR_FATAL_ERROR__(EINVAL);
while (1) {
val = ethr_atomic_read(&e->state);
if (val == ETHR_EVENT_ON__)
return 0;
if (sc == 0)
break;
sc--;
ETHR_SPIN_BODY;
if (--until_yield == 0) {
until_yield = ETHR_YIELD_AFTER_BUSY_LOOPS;
res = ETHR_YIELD();
if (res != 0)
ETHR_FATAL_ERROR__(res);
}
}
if (val != ETHR_EVENT_OFF_WAITER__) {
val = ethr_atomic_cmpxchg(&e->state,
ETHR_EVENT_OFF_WAITER__,
ETHR_EVENT_OFF__);
if (val == ETHR_EVENT_ON__)
return 0;
ETHR_ASSERT(val == ETHR_EVENT_OFF__);
}
ETHR_ASSERT(val == ETHR_EVENT_OFF_WAITER__
|| val == ETHR_EVENT_OFF__);
res = pthread_mutex_lock(&e->mtx);
if (res != 0)
ETHR_FATAL_ERROR__(res);
while (1) {
val = ethr_atomic_read(&e->state);
if (val == ETHR_EVENT_ON__)
break;
res = pthread_cond_wait(&e->cnd, &e->mtx);
if (res == EINTR)
break;
if (res != 0)
ETHR_FATAL_ERROR__(res);
}
ulres = pthread_mutex_unlock(&e->mtx);
if (ulres != 0)
ETHR_FATAL_ERROR__(ulres);
return res; /* 0 || EINTR */
}
#else
#error No ethread event implementation
#endif
void
ethr_event_reset(ethr_event *e)
{
ethr_event_reset__(e);
}
void
ethr_event_set(ethr_event *e)
{
ethr_event_set__(e);
}
int
ethr_event_wait(ethr_event *e)
{
return wait__(e, 0);
}
int
ethr_event_swait(ethr_event *e, int spincount)
{
return wait__(e, spincount);
}
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