event/BufferedSocket: move output buffer to FullyBufferedSocket

BufferedSocket has just an input buffer, and FullyBufferedSocket adds
the output buffer.

src/event/FullyBufferedSocket.cxx

@@ -0,0 +1,132 @@
+/*
+ * 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 "FullyBufferedSocket.hxx"
+#include "SocketError.hxx"
+#include "util/fifo_buffer.h"
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+
+#ifndef WIN32
+#include <sys/types.h>
+#include <sys/socket.h>
+#endif
+
+FullyBufferedSocket::ssize_t
+FullyBufferedSocket::DirectWrite(const void *data, size_t length)
+{
+	const auto nbytes = SocketMonitor::Write((const char *)data, length);
+	if (gcc_unlikely(nbytes < 0)) {
+		const auto code = GetSocketError();
+		if (IsSocketErrorAgain(code))
+			return 0;
+
+		Cancel();
+
+		if (IsSocketErrorClosed(code))
+			OnSocketClosed();
+		else
+			OnSocketError(NewSocketError(code));
+	}
+
+	return nbytes;
+}
+
+bool
+FullyBufferedSocket::WriteFromBuffer()
+{
+	assert(IsDefined());
+
+	size_t length;
+	const void *data = output.Read(&length);
+	if (data == nullptr) {
+		CancelWrite();
+		return true;
+	}
+
+	auto nbytes = DirectWrite(data, length);
+	if (gcc_unlikely(nbytes <= 0))
+		return nbytes == 0;
+
+	output.Consume(nbytes);
+
+	if (output.IsEmpty())
+		CancelWrite();
+
+	return true;
+}
+
+bool
+FullyBufferedSocket::Write(const void *data, size_t length)
+{
+	assert(IsDefined());
+
+#if 0
+	/* TODO: disabled because this would add overhead on some callers (the ones that often), but it may be useful */
+
+	if (output.IsEmpty()) {
+		/* try to write it directly first */
+		const auto nbytes = DirectWrite(data, length);
+		if (gcc_likely(nbytes > 0)) {
+			data = (const uint8_t *)data + nbytes;
+			length -= nbytes;
+			if (length == 0)
+				return true;
+		} else if (nbytes < 0)
+			return false;
+	}
+#endif
+
+	if (!output.Append(data, length)) {
+		// TODO
+		OnSocketError(g_error_new_literal(g_quark_from_static_string("buffered_socket"),
+						  0, "Output buffer is full"));
+		return false;
+	}
+
+	ScheduleWrite();
+	return true;
+}
+
+bool
+FullyBufferedSocket::OnSocketReady(unsigned flags)
+{
+	const bool was_empty = output.IsEmpty();
+	if (!BufferedSocket::OnSocketReady(flags))
+		return false;
+
+	if (was_empty && !output.IsEmpty())
+		/* just in case the OnSocketInput() method has added
+		   data to the output buffer: try to send it now
+		   instead of waiting for the next event loop
+		   iteration */
+		flags |= WRITE;
+
+	if (flags & WRITE) {
+		assert(!output.IsEmpty());
+
+		if (!WriteFromBuffer())
+			return false;
+	}
+
+	return true;
+}