Moved generic utility stuff to new library "raul".

git-svn-id: http://svn.drobilla.net/lad/raul@156 a436a847-0d15-0410-975c-d299462d15a1

1 files changed, 63 insertions, 0 deletions

diff --git a/raul/Semaphore.h b/raul/Semaphore.h
new file mode 100644
index 0000000..9a696f9
--- /dev/null
+++ b/raul/Semaphore.h
@@ -0,0 +1,63 @@
+/* This file is part of Ingen.  Copyright (C) 2006 Dave Robillard.
+ * 
+ * Ingen 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; either version 2 of the License, or (at your option) any later
+ * version.
+ * 
+ * Ingen 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 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.,
+ * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef RAUL_SEMAPHORE_H
+#define RAUL_SEMAPHORE_H
+
+#include <semaphore.h>
+
+
+/** Trivial wrapper around POSIX semaphores (zero memory overhead).
+ *
+ * This was created to provide an alternative debuggable implementation of
+ * semaphores based on a cond/mutex pair because semaphore's appeared not to
+ * work in GDB.  Turns out sem_wait can fail when run in GDB, and Debian
+ * really needs to update it's man pages.
+ *
+ * This class remains as a trivial (yet pretty) wrapper/abstraction.
+ */
+class Semaphore {
+public:
+	inline Semaphore(unsigned int initial) { sem_init(&m_sem, 0, initial); }
+	
+	inline ~Semaphore() { sem_destroy(&m_sem); }
+
+	/** Increment (and signal any waiters).
+	 * 
+	 * Realtime safe.
+	 */
+	inline void post() { sem_post(&m_sem); }
+
+	/** Wait until count is > 0, then decrement.
+	 *
+	 * Note that sem_wait always returns 0 in practise.  It returns nonzero
+	 * when run in GDB, so the while is necessary to allow debugging.
+	 *
+	 * Obviously not realtime safe.
+	 */
+	inline void wait() { while (sem_wait(&m_sem) != 0) ; }
+	
+	/** Non-blocking version of wait().
+	 *
+	 * Realtime safe?
+	 */
+	inline int  try_wait() { return sem_trywait(&m_sem); }
+private:
+	sem_t m_sem;
+};
+
+
+#endif // RAUL_SEMAPHORE_H