event/IdleMonitor: new monitor class

Makefile.am

@@ -299,6 +299,7 @@ libevent_a_SOURCES = \
 	src/event/WakeFD.hxx \
 	src/event/SignalMonitor.hxx src/event/SignalMonitor.cxx \
 	src/event/TimeoutMonitor.hxx src/event/TimeoutMonitor.cxx \
+	src/event/IdleMonitor.hxx src/event/IdleMonitor.cxx \
 	src/event/DeferredMonitor.hxx src/event/DeferredMonitor.cxx \
 	src/event/SocketMonitor.cxx src/event/SocketMonitor.hxx \
 	src/event/BufferedSocket.cxx src/event/BufferedSocket.hxx \

src/event/IdleMonitor.cxx

@@ -0,0 +1,64 @@
+/*
+ * 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.
+ */
+
+#include "config.h"
+#include "IdleMonitor.hxx"
+#include "Loop.hxx"
+
+void
+IdleMonitor::Cancel()
+{
+	assert(loop.IsInside());
+
+	if (!IsActive())
+		return;
+
+	g_source_remove(source_id);
+	source_id = 0;
+}
+
+void
+IdleMonitor::Schedule()
+{
+	assert(loop.IsInside());
+
+	if (IsActive())
+		/* already scheduled */
+		return;
+
+	source_id = loop.AddIdle(Callback, this);
+}
+
+void
+IdleMonitor::Run()
+{
+	assert(loop.IsInside());
+	assert(source_id != 0);
+	source_id = 0;
+
+	OnIdle();
+}
+
+gboolean
+IdleMonitor::Callback(gpointer data)
+{
+	IdleMonitor &monitor = *(IdleMonitor *)data;
+	monitor.Run();
+	return false;
+}

src/event/IdleMonitor.hxx

@@ -0,0 +1,66 @@
+/*
+ * 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_SOCKET_IDLE_MONITOR_HXX
+#define MPD_SOCKET_IDLE_MONITOR_HXX
+
+#include "check.h"
+
+#include <glib.h>
+
+class EventLoop;
+
+/**
+ * An event that runs when the EventLoop has become idle, before
+ * waiting for more events.  This class is not thread-safe; all
+ * methods must be run from EventLoop's thread.
+ */
+class IdleMonitor {
+	EventLoop &loop;
+
+	guint source_id;
+
+public:
+	IdleMonitor(EventLoop &_loop)
+		:loop(_loop), source_id(0) {}
+
+	~IdleMonitor() {
+		Cancel();
+	}
+
+	EventLoop &GetEventLoop() const {
+		return loop;
+	}
+
+	bool IsActive() const {
+		return source_id != 0;
+	}
+
+	void Schedule();
+	void Cancel();
+
+protected:
+	virtual void OnIdle() = 0;
+
+private:
+	void Run();
+	static gboolean Callback(gpointer data);
+};
+
+#endif /* MAIN_NOTIFY_H */