path: root/erts/include/internal/pthread/ethr_event.h

/*
 * %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
 */

#if defined(ETHR_HAVE_LINUX_FUTEX) && defined(ETHR_HAVE_NATIVE_ATOMICS)
/* --- Linux futex implementation of ethread events ------------------------- */
#define ETHR_LINUX_FUTEX_IMPL__

#include <sys/syscall.h>
#include <unistd.h>
#include <linux/futex.h>
#include <sys/time.h>

#define ETHR_EVENT_OFF_WAITER__		((ethr_sint32_t) -1)
#define ETHR_EVENT_OFF__		((ethr_sint32_t) 1)
#define ETHR_EVENT_ON__ 		((ethr_sint32_t) 0)

#if defined(FUTEX_WAIT_PRIVATE) && defined(FUTEX_WAKE_PRIVATE)
#  define ETHR_FUTEX_WAIT__ FUTEX_WAIT_PRIVATE
#  define ETHR_FUTEX_WAKE__ FUTEX_WAKE_PRIVATE
#else
#  define ETHR_FUTEX_WAIT__ FUTEX_WAIT
#  define ETHR_FUTEX_WAKE__ FUTEX_WAKE
#endif

typedef struct {
    ethr_atomic32_t futex;
} ethr_event;

#define ETHR_FUTEX__(FTX, OP, VAL)			\
  (-1 == syscall(__NR_futex,				\
		 (void *) ethr_atomic32_addr((FTX)),	\
		 (OP),					\
		 (int) (VAL),				\
		 NULL,					\
		 NULL,					\
		 0)					\
   ? errno : 0)

#if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_EVENT_IMPL__)

static void ETHR_INLINE
ETHR_INLINE_FUNC_NAME_(ethr_event_set)(ethr_event *e)
{
    ethr_sint32_t val;
    ETHR_WRITE_MEMORY_BARRIER;
    val = ethr_atomic32_xchg(&e->futex, ETHR_EVENT_ON__);
    if (val == ETHR_EVENT_OFF_WAITER__) {
	int res = ETHR_FUTEX__(&e->futex, ETHR_FUTEX_WAKE__, 1);
	if (res != 0)
	    ETHR_FATAL_ERROR__(res);
    }
}

static void ETHR_INLINE
ETHR_INLINE_FUNC_NAME_(ethr_event_reset)(ethr_event *e)
{
    ethr_atomic32_set(&e->futex, ETHR_EVENT_OFF__);
    ETHR_MEMORY_BARRIER;
}

#endif

#elif defined(ETHR_PTHREADS)
/* --- Posix mutex/cond implementation of events ---------------------------- */

typedef struct {
    ethr_atomic32_t state;
    pthread_mutex_t mtx;
    pthread_cond_t cnd;
} ethr_event;

#define ETHR_EVENT_OFF_WAITER__		-1L
#define ETHR_EVENT_OFF__		1L
#define ETHR_EVENT_ON__ 		0L

#if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_EVENT_IMPL__)

static void ETHR_INLINE
ETHR_INLINE_FUNC_NAME_(ethr_event_set)(ethr_event *e)
{
    ethr_sint32_t val;
    ETHR_WRITE_MEMORY_BARRIER;
    val = ethr_atomic32_xchg(&e->state, ETHR_EVENT_ON__);
    if (val == ETHR_EVENT_OFF_WAITER__) {
	int res = pthread_mutex_lock(&e->mtx);
	if (res != 0)
	    ETHR_FATAL_ERROR__(res);
	res = pthread_cond_signal(&e->cnd);
	if (res != 0)
	    ETHR_FATAL_ERROR__(res);
	res = pthread_mutex_unlock(&e->mtx);
	if (res != 0)
	    ETHR_FATAL_ERROR__(res);
    }
}

static void ETHR_INLINE
ETHR_INLINE_FUNC_NAME_(ethr_event_reset)(ethr_event *e)
{
    ethr_atomic32_set(&e->state, ETHR_EVENT_OFF__);
    ETHR_MEMORY_BARRIER;
}

#endif

#endif

int ethr_event_init(ethr_event *e);
int ethr_event_destroy(ethr_event *e);
int ethr_event_wait(ethr_event *e);
int ethr_event_swait(ethr_event *e, int spincount);
#if !defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_EVENT_IMPL__)
void ethr_event_set(ethr_event *e);
void ethr_event_reset(ethr_event *e);
#endif