event/SocketMonitor: wrapper class for GSource + GPollFD

src/event/BufferedSocket.hxx

@@ -0,0 +1,125 @@
+/*
+ * 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_BUFFERED_SOCKET_HXX
+#define MPD_BUFFERED_SOCKET_HXX
+
+#include "check.h"
+#include "SocketMonitor.hxx"
+#include "util/PeakBuffer.hxx"
+#include "gcc.h"
+
+#include <type_traits>
+
+#include <stddef.h>
+
+struct fifo_buffer;
+class EventLoop;
+
+class BufferedSocket : private SocketMonitor {
+	typedef std::make_signed<size_t>::type ssize_t;
+
+	fifo_buffer *input;
+	PeakBuffer output;
+
+public:
+	BufferedSocket(int _fd, EventLoop &_loop,
+		       size_t normal_size, size_t peak_size=0)
+		:SocketMonitor(_fd, _loop), input(nullptr),
+		 output(normal_size, peak_size) {
+		ScheduleRead();
+	}
+
+	~BufferedSocket();
+
+	using SocketMonitor::IsDefined;
+	using SocketMonitor::Close;
+
+private:
+	ssize_t DirectWrite(const void *data, size_t length);
+	ssize_t DirectRead(void *data, size_t length);
+
+	/**
+	 * Send data from the output buffer to the socket.
+	 *
+	 * @return false if the socket has been closed
+	 */
+	bool WriteFromBuffer();
+
+	/**
+	 * Receive data from the socket to the input buffer.
+	 *
+	 * @return false if the socket has been closed
+	 */
+	bool ReadToBuffer();
+
+protected:
+	/**
+	 * @return false if the socket has been closed
+	 */
+	bool Write(const void *data, size_t length);
+
+	/**
+	 * @return false if the socket has been closed
+	 */
+	bool ResumeInput();
+
+	/**
+	 * Mark a portion of the input buffer "consumed".  Only
+	 * allowed to be called from OnSocketInput().  This method
+	 * does not invalidate the pointer passed to OnSocketInput()
+	 * yet.
+	 */
+	void ConsumeInput(size_t nbytes);
+
+	enum class InputResult {
+		/**
+		 * The method was successful, and it is ready to
+		 * read more data.
+		 */
+		MORE,
+
+		/**
+		 * The method does not want to get more data for now.
+		 * It will call ResumeInput() when it's ready for
+		 * more.
+		 */
+		PAUSE,
+
+		/**
+		 * The method wants to be called again immediately, if
+		 * there's more data in the buffer.
+		 */
+		AGAIN,
+
+		/**
+		 * The method has closed the socket.
+		 */
+		CLOSED,
+	};
+
+	virtual InputResult OnSocketInput(const void *data, size_t length) = 0;
+	virtual void OnSocketError(GError *error) = 0;
+	virtual void OnSocketClosed() = 0;
+
+private:
+	virtual void OnSocketReady(unsigned flags) override;
+};
+
+#endif