io_thread: convert to C++

src/IOThread.cxx

@@ -0,0 +1,197 @@
+/*
+ * 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 "IOThread.hxx"
+#include "thread/Mutex.hxx"
+#include "thread/Cond.hxx"
+
+#include <assert.h>
+
+static struct {
+	Mutex mutex;
+	Cond cond;
+
+	GMainContext *context;
+	GMainLoop *loop;
+	GThread *thread;
+} io;
+
+void
+io_thread_run(void)
+{
+	assert(io_thread_inside());
+	assert(io.context != NULL);
+	assert(io.loop != NULL);
+
+	g_main_loop_run(io.loop);
+}
+
+static gpointer
+io_thread_func(G_GNUC_UNUSED gpointer arg)
+{
+	/* lock+unlock to synchronize with io_thread_start(), to be
+	   sure that io.thread is set */
+	io.mutex.lock();
+	io.mutex.unlock();
+
+	io_thread_run();
+	return NULL;
+}
+
+void
+io_thread_init(void)
+{
+	assert(io.context == NULL);
+	assert(io.loop == NULL);
+	assert(io.thread == NULL);
+
+	io.context = g_main_context_new();
+	io.loop = g_main_loop_new(io.context, false);
+}
+
+bool
+io_thread_start(GError **error_r)
+{
+	assert(io.context != NULL);
+	assert(io.loop != NULL);
+	assert(io.thread == NULL);
+
+	io.mutex.lock();
+	io.thread = g_thread_create(io_thread_func, NULL, true, error_r);
+	io.mutex.unlock();
+	if (io.thread == NULL)
+		return false;
+
+	return true;
+}
+
+void
+io_thread_quit(void)
+{
+	assert(io.loop != NULL);
+
+	g_main_loop_quit(io.loop);
+}
+
+void
+io_thread_deinit(void)
+{
+	if (io.thread != NULL) {
+		io_thread_quit();
+
+		g_thread_join(io.thread);
+	}
+
+	if (io.loop != NULL)
+		g_main_loop_unref(io.loop);
+
+	if (io.context != NULL)
+		g_main_context_unref(io.context);
+}
+
+GMainContext *
+io_thread_context(void)
+{
+	return io.context;
+}
+
+bool
+io_thread_inside(void)
+{
+	return io.thread != NULL && g_thread_self() == io.thread;
+}
+
+guint
+io_thread_idle_add(GSourceFunc function, gpointer data)
+{
+	GSource *source = g_idle_source_new();
+	g_source_set_callback(source, function, data, NULL);
+	guint id = g_source_attach(source, io.context);
+	g_source_unref(source);
+	return id;
+}
+
+GSource *
+io_thread_timeout_add(guint interval_ms, GSourceFunc function, gpointer data)
+{
+	GSource *source = g_timeout_source_new(interval_ms);
+	g_source_set_callback(source, function, data, NULL);
+	g_source_attach(source, io.context);
+	return source;
+}
+
+GSource *
+io_thread_timeout_add_seconds(guint interval,
+			      GSourceFunc function, gpointer data)
+{
+	GSource *source = g_timeout_source_new_seconds(interval);
+	g_source_set_callback(source, function, data, NULL);
+	g_source_attach(source, io.context);
+	return source;
+}
+
+struct call_data {
+	GThreadFunc function;
+	gpointer data;
+	bool done;
+	gpointer result;
+};
+
+static gboolean
+io_thread_call_func(gpointer _data)
+{
+	struct call_data *data = (struct call_data *)_data;
+
+	gpointer result = data->function(data->data);
+
+	io.mutex.lock();
+	data->done = true;
+	data->result = result;
+	io.cond.broadcast();
+	io.mutex.unlock();
+
+	return false;
+}
+
+gpointer
+io_thread_call(GThreadFunc function, gpointer _data)
+{
+	assert(io.thread != NULL);
+
+	if (io_thread_inside())
+		/* we're already in the I/O thread - no
+		   synchronization needed */
+		return function(_data);
+
+	struct call_data data = {
+		function,
+		_data,
+		false,
+		nullptr,
+	};
+
+	io_thread_idle_add(io_thread_call_func, &data);
+
+	io.mutex.lock();
+	while (!data.done)
+		io.cond.wait(io.mutex);
+	io.mutex.unlock();
+
+	return data.result;
+}