Merge branch 'rickard/ethread-rewrite/OTP-8544' into dev

* rickard/ethread-rewrite/OTP-8544:
  Rewrite ethread library

1 files changed, 219 insertions, 0 deletions

diff --git a/erts/lib_src/pthread/ethr_event.c b/erts/lib_src/pthread/ethr_event.c
new file mode 100644
index 0000000000..6731c0eb46
--- /dev/null
+++ b/erts/lib_src/pthread/ethr_event.c
@@ -0,0 +1,219 @@
+/*
+ * %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__
+
+#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;
+    long 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;
+    long 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);
+}