1 files changed, 45 insertions, 0 deletions
diff --git a/src/semaphore.h b/src/semaphore.h
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+/* Authors: Martin Nagy <mnagy@redhat.com>
+ *
+ * Copyright (C) 2008  Red Hat
+ * see file 'COPYING' for use and warranty information
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 only
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _LD_SEMAPHORE_H_
+#define _LD_SEMAPHORE_H_
+
+#include <isc/condition.h>
+#include <isc/mutex.h>
+
+/*
+ * Semaphore can be "acquired" multiple times. However, it has a maximum
+ * number of times someone can acquire him. If a semaphore is already acquired
+ * more times than allowed, it will block until other thread release its,
+ */
+struct semaphore {
+	int value;		/* Maximum number of times you can LOCK()) */
+	isc_mutex_t mutex;	/* Mutex protecting this whole struct.     */
+	isc_condition_t cond;	/* Condition used for waiting on release.  */
+};
+
+typedef struct semaphore	semaphore_t;
+
+/* Public functions. */
+isc_result_t	semaphore_init(semaphore_t *sem, int value);
+void		semaphore_destroy(semaphore_t *sem);
+void		semaphore_wait(semaphore_t *sem);
+void		semaphore_signal(semaphore_t *sem);
+
+#endif /* !_LD_SEMAPHORE_H_ */