event/EventFD: move to libsystem

src/system/EventFD.hxx

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2003-2013 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_EVENT_FD_HXX
+#define MPD_EVENT_FD_HXX
+
+#include "check.h"
+
+/**
+ * A class that wraps eventfd().
+ *
+ * Errors in the constructor are fatal.
+ */
+class EventFD {
+	int fd;
+
+public:
+	EventFD();
+	~EventFD();
+
+	EventFD(const EventFD &other) = delete;
+	EventFD &operator=(const EventFD &other) = delete;
+
+	int Get() const {
+		return fd;
+	}
+
+	/**
+	 * Checks if Write() was called at least once since the last
+	 * Read() call.
+	 */
+	bool Read();
+
+	/**
+	 * Wakes up the reader.  Multiple calls to this function will
+	 * be combined to one wakeup.
+	 */
+	void Write();
+};
+
+#endif