GlobalEvents: move code to class WakeFD

Makefile.am

@@ -9,6 +9,7 @@ bin_PROGRAMS = src/mpd
 
 noinst_LIBRARIES = \
 	libutil.a \
+	libevent.a \
 	libpcm.a \
 	libtag.a \
 	libinput.a \
@@ -39,6 +40,7 @@ src_mpd_LDADD = \
 	$(ENCODER_LIBS) \
 	$(MIXER_LIBS) \
 	libutil.a \
+	libevent.a \
 	$(SYSTEMD_DAEMON_LIBS) \
 	$(GLIB_LIBS)
 
@@ -348,6 +350,11 @@ libutil_a_SOURCES = \
 	src/util/byte_reverse.c src/util/byte_reverse.h \
 	src/util/bit_reverse.c src/util/bit_reverse.h
 
+# Event loop library
+
+libevent_a_SOURCES = \
+	src/event/WakeFD.cxx
+
 # PCM library
 
 libpcm_a_SOURCES = \

src/GlobalEvents.cxx

@@ -19,22 +19,20 @@
 
 #include "config.h"
 #include "GlobalEvents.hxx"
+#include "event/WakeFD.hxx"
 #include "thread/Mutex.hxx"
-#include "fd_util.h"
 #include "mpd_error.h"
 
 #include <assert.h>
 #include <glib.h>
 #include <string.h>
 #include <errno.h>
-#include <unistd.h>
 
 #undef G_LOG_DOMAIN
 #define G_LOG_DOMAIN "global_events"
 
 namespace GlobalEvents {
-	static int fds[2];
-	static GIOChannel *channel;
+	static WakeFD wake_fd;
 	static guint source_id;
 	static Mutex mutex;
 	static bool flags[MAX];
@@ -58,14 +56,8 @@ GlobalEventCallback(G_GNUC_UNUSED GIOChannel *source,
 		    G_GNUC_UNUSED GIOCondition condition,
 		    G_GNUC_UNUSED gpointer data)
 {
-	char buffer[256];
-	gsize bytes_read;
-	GError *error = NULL;
-	GIOStatus status = g_io_channel_read_chars(GlobalEvents::channel,
-						   buffer, sizeof(buffer),
-						   &bytes_read, &error);
-	if (status == G_IO_STATUS_ERROR)
-		MPD_ERROR("error reading from pipe: %s", error->message);
+	if (!GlobalEvents::wake_fd.Read())
+		return true;
 
 	bool events[GlobalEvents::MAX];
 	GlobalEvents::mutex.lock();
@@ -85,32 +77,26 @@ GlobalEventCallback(G_GNUC_UNUSED GIOChannel *source,
 void
 GlobalEvents::Initialize()
 {
-	if (pipe_cloexec_nonblock(fds) < 0)
+	if (!wake_fd.Create())
 		MPD_ERROR("Couldn't open pipe: %s", strerror(errno));
 
 #ifndef G_OS_WIN32
-	channel = g_io_channel_unix_new(fds[0]);
+	GIOChannel *channel = g_io_channel_unix_new(wake_fd.Get());
 #else
-	channel = g_io_channel_win32_new_fd(fds[0]);
+	GIOChannel *channel = g_io_channel_win32_new_fd(wake_fd.Get());
 #endif
-	g_io_channel_set_encoding(channel, NULL, NULL);
-	g_io_channel_set_buffered(channel, false);
 
 	source_id = g_io_add_watch(channel, G_IO_IN,
 				   GlobalEventCallback, NULL);
+	g_io_channel_unref(channel);
 }
 
 void
 GlobalEvents::Deinitialize()
 {
 	g_source_remove(source_id);
-	g_io_channel_unref(channel);
 
-#ifndef WIN32
-	/* By some strange reason this call hangs on Win32 */
-	close(fds[0]);
-#endif
-	close(fds[1]);
+	wake_fd.Destroy();
 }
 
 void
@@ -137,9 +123,7 @@ GlobalEvents::Emit(Event event)
 	flags[event] = true;
 	mutex.unlock();
 
-	ssize_t w = write(fds[1], "", 1);
-	if (w < 0 && errno != EAGAIN && errno != EINTR)
-		MPD_ERROR("error writing to pipe: %s", strerror(errno));
+	wake_fd.Write();
 }
 
 void
@@ -149,5 +133,5 @@ GlobalEvents::FastEmit(Event event)
 
 	flags[event] = true;
 
-	G_GNUC_UNUSED ssize_t nbytes = write(fds[1], "", 1);
+	wake_fd.Write();
 }

src/event/WakeFD.cxx

@@ -0,0 +1,68 @@
+/*
+ * 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 "WakeFD.hxx"
+#include "fd_util.h"
+#include "gcc.h"
+
+#include <unistd.h>
+
+bool
+WakeFD::Create()
+{
+	assert(fds[0] == -1);
+	assert(fds[1] == -1);
+
+	return pipe_cloexec_nonblock(fds) >= 0;
+}
+
+void
+WakeFD::Destroy()
+{
+#ifndef WIN32
+	/* By some strange reason this call hangs on Win32 */
+	close(fds[0]);
+#endif
+	close(fds[1]);
+
+#ifndef NDEBUG
+	fds[0] = -1;
+	fds[1] = -1;
+#endif
+}
+
+bool
+WakeFD::Read()
+{
+	assert(fds[0] >= 0);
+	assert(fds[1] >= 0);
+
+	char buffer[256];
+	return read(fds[0], buffer, sizeof(buffer)) > 0;
+}
+
+void
+WakeFD::Write()
+{
+	assert(fds[0] >= 0);
+	assert(fds[1] >= 0);
+
+	gcc_unused ssize_t nbytes = write(fds[1], "", 1);
+}

src/event/WakeFD.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_WAKE_FD_HXX
+#define MPD_WAKE_FD_HXX
+
+#include "check.h"
+
+#include <assert.h>
+
+/**
+ * This class can be used to wake up an I/O event loop.
+ *
+ * For optimization purposes, this class does not have a constructor
+ * or a destructor.
+ */
+class WakeFD {
+	int fds[2];
+
+public:
+#ifdef NDEBUG
+	WakeFD() = default;
+#else
+	WakeFD():fds{-1, -1} {};
+#endif
+
+	WakeFD(const WakeFD &other) = delete;
+	WakeFD &operator=(const WakeFD &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 */