configure.ac: add option --enable-eventfd

Remove the runtime check for eventfd(), hard-code the feature once
it's been selected at compile time.  The class WakeFD is splitted into
EventFD and EventPipe, using WakeFD as a macro diversion.

1 files changed, 69 insertions, 0 deletions

diff --git a/src/event/EventPipe.hxx b/src/event/EventPipe.hxx
new file mode 100644
index 000000000..9c9446d8e
--- /dev/null
+++ b/src/event/EventPipe.hxx
@@ -0,0 +1,69 @@
+/*
+ * 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_PIPE_HXX
+#define MPD_EVENT_PIPE_HXX
+
+#include "check.h"
+
+#include <assert.h>
+
+/**
+ * A pipe that can be used to trigger an event to the read side.
+ *
+ * For optimization purposes, this class does not have a constructor
+ * or a destructor.
+ */
+class EventPipe {
+	int fds[2];
+
+public:
+#ifdef NDEBUG
+	EventPipe() = default;
+#else
+	EventPipe():fds{-1, -1} {};
+#endif
+
+	EventPipe(const EventPipe &other) = delete;
+	EventPipe &operator=(const EventPipe &other) = delete;
+
+	bool Create();
+	void Destroy();
+
+	int Get() const {
+		assert(fds[0] >= 0);
+		assert(fds[1] >= 0);
+
+		return fds[0];
+	}
+
+	/**
+	 * 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 /* MAIN_NOTIFY_H */