1 files changed, 99 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_once.c b/lib/libthr/thread/thr_once.c
new file mode 100644
index 0000000..4fe392c
--- /dev/null
+++ b/lib/libthr/thread/thr_once.c
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2005, David Xu <davidxu@freebsd.org>
+ * All rights reserved.
+ *
+ * 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 unmodified, 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.
+ *
+ * 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.
+ *
+ * $FreeBSD$
+ *
+ */
+
+#include "namespace.h"
+#include <pthread.h>
+#include "un-namespace.h"
+
+#include "thr_private.h"
+
+__weak_reference(_pthread_once, pthread_once);
+
+#define ONCE_NEVER_DONE		PTHREAD_NEEDS_INIT
+#define ONCE_DONE		PTHREAD_DONE_INIT
+#define	ONCE_IN_PROGRESS	0x02
+#define	ONCE_MASK		0x03
+
+static pthread_mutex_t		_thr_once_lock = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t		_thr_once_cv = PTHREAD_COND_INITIALIZER;
+
+/*
+ * POSIX:
+ * The pthread_once() function is not a cancellation point. However,
+ * if init_routine is a cancellation point and is canceled, the effect
+ * on once_control shall be as if pthread_once() was never called.
+ */
+ 
+static void
+once_cancel_handler(void *arg)
+{
+	pthread_once_t *once_control = arg;
+
+	_pthread_mutex_lock(&_thr_once_lock);
+	once_control->state = ONCE_NEVER_DONE;
+	_pthread_mutex_unlock(&_thr_once_lock);
+	_pthread_cond_broadcast(&_thr_once_cv);
+}
+
+int
+_pthread_once(pthread_once_t *once_control, void (*init_routine) (void))
+{
+	int wakeup = 0;
+
+	if (once_control->state == ONCE_DONE)
+		return (0);
+	_pthread_mutex_lock(&_thr_once_lock);
+	while (*(volatile int *)&(once_control->state) == ONCE_IN_PROGRESS)
+		_pthread_cond_wait(&_thr_once_cv, &_thr_once_lock);
+	/*
+	 * If previous thread was canceled, then the state still
+	 * could be ONCE_NEVER_DONE, we need to check it again.
+	 */
+	if (*(volatile int *)&(once_control->state) == ONCE_NEVER_DONE) {
+		once_control->state = ONCE_IN_PROGRESS;
+		_pthread_mutex_unlock(&_thr_once_lock);
+		_pthread_cleanup_push(once_cancel_handler, once_control);
+		init_routine();
+		_pthread_cleanup_pop(0);
+		_pthread_mutex_lock(&_thr_once_lock);
+		once_control->state = ONCE_DONE;
+		wakeup = 1;
+	}
+	_pthread_mutex_unlock(&_thr_once_lock);
+	if (wakeup)
+		_pthread_cond_broadcast(&_thr_once_cv);
+	return (0);
+}
+
+void
+_thr_once_init()
+{
+	_thr_once_lock = PTHREAD_MUTEX_INITIALIZER;
+	_thr_once_cv = PTHREAD_COND_INITIALIZER;
+}