Add wrapping class for glib atomic counter

libs/pbd/pbd/atomic_counter.h

@@ -0,0 +1,99 @@
+/*
+    Copyright (C) 2010 Tim Mayberry
+
+    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; either version 2 of the License, or
+    (at your option) any later version.
+
+    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., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifndef PBD_ATOMIC_COUNTER_H
+#define PBD_ATOMIC_COUNTER_H
+
+#include <glib.h>
+
+namespace PBD {
+
+class atomic_counter
+{
+	/**
+	 * Prevent copying and assignment
+	 */
+	atomic_counter (const atomic_counter&);
+	atomic_counter& operator= (const atomic_counter&);
+
+public:
+
+	atomic_counter (gint value = 0)
+		:
+			m_value(value)
+	{ }
+
+	gint get() const
+	{
+		return g_atomic_int_get (&m_value);
+	}
+
+	void set (gint new_value)
+	{
+		g_atomic_int_set (&m_value, new_value);
+	}
+
+	void increment ()
+	{
+		g_atomic_int_inc (&m_value);
+	}
+
+	void operator++ ()
+	{
+		increment ();
+	}
+
+	bool decrement_and_test ()
+	{
+		return g_atomic_int_dec_and_test (&m_value);
+	}
+	
+	bool operator-- ()
+	{
+		return decrement_and_test ();
+	}
+
+	bool compare_and_exchange (gint old_value, gint new_value)
+	{
+		return g_atomic_int_compare_and_exchange
+			(
+			 &m_value,
+			 old_value,
+			 new_value
+			);
+	}
+
+	/**
+	 * convenience method, \see compare_and_exchange
+	 */
+	bool cas (gint old_value, gint new_value)
+	{
+		return compare_and_exchange (old_value, new_value);
+	}
+
+private:
+
+	// Has to be mutable when using the apple version of gcc.
+	mutable volatile gint             m_value;
+
+};
+
+} // namespace PBD
+
+#endif // PBD_ATOMIC_COUNTER_H