event: add function BlockingCall()

Replaces io_thread_call().  This approach is more generic and easier
to use due to std::function.

Makefile.am

@@ -304,6 +304,7 @@ libevent_a_SOURCES = \
 	src/event/FullyBufferedSocket.cxx src/event/FullyBufferedSocket.hxx \
 	src/event/MultiSocketMonitor.cxx src/event/MultiSocketMonitor.hxx \
 	src/event/ServerSocket.cxx src/event/ServerSocket.hxx \
+	src/event/Call.hxx src/event/Call.cxx \
 	src/event/Loop.cxx src/event/Loop.hxx
 
 # PCM library

src/IOThread.cxx

@@ -115,53 +115,3 @@ io_thread_inside(void)
 {
 	return io.thread != NULL && g_thread_self() == io.thread;
 }
-
-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.loop->AddIdle(io_thread_call_func, &data);
-
-	io.mutex.lock();
-	while (!data.done)
-		io.cond.wait(io.mutex);
-	io.mutex.unlock();
-
-	return data.result;
-}

src/IOThread.hxx

@@ -62,10 +62,4 @@ gcc_pure
 bool
 io_thread_inside(void);
 
-/**
- * Call a function synchronously in the I/O thread.
- */
-gpointer
-io_thread_call(GThreadFunc function, gpointer data);
-
 #endif

src/event/Call.cxx

@@ -0,0 +1,72 @@
+/*
+ * 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 "Call.hxx"
+#include "Loop.hxx"
+#include "DeferredMonitor.hxx"
+#include "thread/Mutex.hxx"
+#include "thread/Cond.hxx"
+#include "gcc.h"
+
+#include <assert.h>
+
+class BlockingCallMonitor final : DeferredMonitor {
+	const std::function<void()> f;
+
+	Mutex mutex;
+	Cond cond;
+
+	bool done;
+
+public:
+	BlockingCallMonitor(EventLoop &_loop, std::function<void()> &&_f)
+		:DeferredMonitor(_loop), f(std::move(_f)), done(false) {}
+
+	void Run() {
+		assert(!done);
+
+		Schedule();
+
+		mutex.lock();
+		while (!done)
+			cond.wait(mutex);
+		mutex.unlock();
+	}
+
+private:
+	virtual void RunDeferred() override {
+		f();
+	}
+};
+
+void
+BlockingCall(EventLoop &loop, std::function<void()> &&f)
+{
+	if (loop.IsInside()) {
+		/* we're already inside the loop - we can simply call
+		   the function */
+		f();
+	} else {
+		/* outside the EventLoop's thread - defer execution to
+		   the EventLoop, wait for completion */
+		BlockingCallMonitor m(loop, std::move(f));
+		m.Run();
+	}
+}

src/event/Call.hxx

@@ -0,0 +1,36 @@
+/*
+ * 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_CALL_HXX
+#define MPD_EVENT_CALL_HXX
+
+#include "check.h"
+
+#include <functional>
+
+class EventLoop;
+
+/**
+ * Call the given function in the context of the #EventLoop, and wait
+ * for it to finish.
+ */
+void
+BlockingCall(EventLoop &loop, std::function<void()> &&f);
+
+#endif /* MAIN_NOTIFY_H */

src/input/CurlInputPlugin.cxx

@@ -26,7 +26,7 @@
 #include "Tag.hxx"
 #include "IcyMetaDataParser.hxx"
 #include "event/MultiSocketMonitor.hxx"
-#include "event/Loop.hxx"
+#include "event/Call.hxx"
 #include "IOThread.hxx"
 
 #include <assert.h>
@@ -252,19 +252,15 @@ input_curl_find_request(CURL *easy)
 	return NULL;
 }
 
-static gpointer
+static void
-input_curl_resume(gpointer data)
+input_curl_resume(struct input_curl *c)
 {
 	assert(io_thread_inside());
 
-	struct input_curl *c = (struct input_curl *)data;
-
 	if (c->paused) {
 		c->paused = false;
 		curl_easy_pause(c->easy, CURLPAUSE_CONT);
 	}
-
-	return NULL;
 }
 
 /**
@@ -358,21 +354,6 @@ input_curl_easy_add(struct input_curl *c, GError **error_r)
 	return true;
 }
 
-struct easy_add_params {
-	struct input_curl *c;
-	GError **error_r;
-};
-
-static gpointer
-input_curl_easy_add_callback(gpointer data)
-{
-	const struct easy_add_params *params =
-		(const struct easy_add_params *)data;
-
-	bool success = input_curl_easy_add(params->c, params->error_r);
-	return GUINT_TO_POINTER(success);
-}
-
 /**
  * Call input_curl_easy_add() in the I/O thread.  May be called from
  * any thread.  Caller must not hold a mutex.
@@ -383,14 +364,11 @@ input_curl_easy_add_indirect(struct input_curl *c, GError **error_r)
 	assert(c != NULL);
 	assert(c->easy != NULL);
 
-	struct easy_add_params params = {
+	bool result;
-		c,
+	BlockingCall(io_thread_get(), [c, error_r, &result](){
-		error_r,
+			result = input_curl_easy_add(c, error_r);
-	};
+		});
-
+	return result;
-	gpointer result =
-		io_thread_call(input_curl_easy_add_callback, &params);
-	return GPOINTER_TO_UINT(result);
 }
 
 /**
@@ -421,17 +399,6 @@ input_curl_easy_free(struct input_curl *c)
 	c->range = NULL;
 }
 
-static gpointer
-input_curl_easy_free_callback(gpointer data)
-{
-	struct input_curl *c = (struct input_curl *)data;
-
-	input_curl_easy_free(c);
-	curl.sockets->InvalidateSockets();
-
-	return NULL;
-}
-
 /**
  * Frees the current "libcurl easy" handle, and everything associated
  * with it.
@@ -441,7 +408,11 @@ input_curl_easy_free_callback(gpointer data)
 static void
 input_curl_easy_free_indirect(struct input_curl *c)
 {
-	io_thread_call(input_curl_easy_free_callback, c);
+	BlockingCall(io_thread_get(), [c](){
+			input_curl_easy_free(c);
+			curl.sockets->InvalidateSockets();
+		});
+
 	assert(c->easy == NULL);
 }
 
@@ -654,20 +625,14 @@ input_curl_init(const config_param &param,
 	return true;
 }
 
-static gpointer
-curl_destroy_sources(gcc_unused gpointer data)
-{
-	delete curl.sockets;
-
-	return NULL;
-}
-
 static void
 input_curl_finish(void)
 {
 	assert(curl.requests.empty());
 
-	io_thread_call(curl_destroy_sources, NULL);
+	BlockingCall(io_thread_get(), [](){
+			delete curl.sockets;
+		});
 
 	curl_multi_cleanup(curl.multi);
 
@@ -854,7 +819,11 @@ input_curl_read(struct input_stream *is, void *ptr, size_t size,
 
 	if (c->paused && curl_total_buffer_size(c) < CURL_RESUME_AT) {
 		c->base.mutex.unlock();
-		io_thread_call(input_curl_resume, c);
+
+		BlockingCall(io_thread_get(), [c](){
+				input_curl_resume(c);
+			});
+
 		c->base.mutex.lock();
 	}