event/MaskMonitor: new class to replace code in GlobalEvents and Idle

src/event/MaskMonitor.cxx

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2003-2016 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 "MaskMonitor.hxx"
+
+void
+MaskMonitor::OrMask(unsigned new_mask)
+{
+	if (pending_mask.fetch_or(new_mask) == 0)
+		DeferredMonitor::Schedule();
+}
+
+void
+MaskMonitor::RunDeferred()
+{
+	const unsigned mask = pending_mask.exchange(0);
+	if (mask != 0)
+		HandleMask(mask);
+}

src/event/MaskMonitor.hxx

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2003-2016 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_MASK_MONITOR_HXX
+#define MPD_EVENT_MASK_MONITOR_HXX
+
+#include "check.h"
+#include "DeferredMonitor.hxx"
+
+#include <atomic>
+
+/**
+ * Manage a bit mask of events that have occurred.  Every time the
+ * mask becomes non-zero, OnMask() is called in #EventLoop's thread.
+ *
+ * This class is thread-safe.
+ */
+class MaskMonitor : DeferredMonitor {
+	std::atomic_uint pending_mask;
+
+public:
+	explicit MaskMonitor(EventLoop &_loop)
+		:DeferredMonitor(_loop), pending_mask(0) {}
+
+	using DeferredMonitor::GetEventLoop;
+	using DeferredMonitor::Cancel;
+
+	void OrMask(unsigned new_mask);
+
+protected:
+	virtual void HandleMask(unsigned mask) = 0;
+
+	/* virtual methode from class DeferredMonitor */
+	void RunDeferred() override;
+};
+
+#endif