event/SocketMonitor: wrapper class for GSource + GPollFD

src/event/BufferedSocket.cxx

@@ -0,0 +1,256 @@
+/*
+ * 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 "BufferedSocket.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
+
+BufferedSocket::~BufferedSocket()
+{
+	if (input != nullptr)
+		fifo_buffer_free(input);
+}
+
+BufferedSocket::ssize_t
+BufferedSocket::DirectWrite(const void *data, size_t length)
+{
+	int flags = 0;
+#ifdef MSG_NOSIGNAL
+	flags |= MSG_NOSIGNAL;
+#endif
+#ifdef MSG_DONTWAIT
+	flags |= MSG_DONTWAIT;
+#endif
+
+	const auto nbytes = send(Get(), (const char *)data, length, flags);
+	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;
+}
+
+ssize_t
+BufferedSocket::DirectRead(void *data, size_t length)
+{
+	int flags = 0;
+#ifdef MSG_DONTWAIT
+	flags |= MSG_DONTWAIT;
+#endif
+
+	const auto nbytes = recv(Get(), (char *)data, length, flags);
+	if (gcc_likely(nbytes > 0))
+		return nbytes;
+
+	if (nbytes == 0) {
+		OnSocketClosed();
+		return -1;
+	}
+
+	const auto code = GetSocketError();
+	if (IsSocketErrorAgain(code))
+		return 0;
+
+	if (IsSocketErrorClosed(code))
+		OnSocketClosed();
+	else
+		OnSocketError(NewSocketError(code));
+	return -1;
+}
+
+bool
+BufferedSocket::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
+BufferedSocket::ReadToBuffer()
+{
+	assert(IsDefined());
+
+	if (input == nullptr)
+		input = fifo_buffer_new(8192);
+
+	size_t length;
+	void *buffer = fifo_buffer_write(input, &length);
+	assert(buffer != nullptr);
+
+	const auto nbytes = DirectRead(buffer, length);
+	if (nbytes > 0)
+		fifo_buffer_append(input, nbytes);
+
+	return nbytes >= 0;
+}
+
+bool
+BufferedSocket::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
+BufferedSocket::ResumeInput()
+{
+	assert(IsDefined());
+
+	if (input == nullptr) {
+		ScheduleRead();
+		return true;
+	}
+
+	while (true) {
+		size_t length;
+		const void *data = fifo_buffer_read(input, &length);
+		if (data == nullptr) {
+			ScheduleRead();
+			return true;
+		}
+
+		const auto result = OnSocketInput(data, length);
+		switch (result) {
+		case InputResult::MORE:
+			if (fifo_buffer_is_full(input)) {
+				// TODO
+				OnSocketError(g_error_new_literal(g_quark_from_static_string("buffered_socket"),
+								  0, "Input buffer is full"));
+				return false;
+			}
+
+			ScheduleRead();
+			return true;
+
+		case InputResult::PAUSE:
+			CancelRead();
+			return true;
+
+		case InputResult::AGAIN:
+			continue;
+
+		case InputResult::CLOSED:
+			return false;
+		}
+	}
+}
+
+void
+BufferedSocket::ConsumeInput(size_t nbytes)
+{
+	assert(IsDefined());
+
+	fifo_buffer_consume(input, nbytes);
+}
+
+void
+BufferedSocket::OnSocketReady(unsigned flags)
+{
+	assert(IsDefined());
+
+	if (gcc_unlikely(flags & (ERROR|HANGUP))) {
+		OnSocketClosed();
+		return;
+	}
+
+	if (flags & READ) {
+		assert(input == nullptr || !fifo_buffer_is_full(input));
+
+		if (!ReadToBuffer() || !ResumeInput())
+			return;
+
+		if (input == nullptr || !fifo_buffer_is_full(input))
+			ScheduleRead();
+
+		/* 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 */
+		if (!output.IsEmpty())
+			flags |= WRITE;
+	}
+
+	if (flags & WRITE) {
+		assert(!output.IsEmpty());
+
+		if (!WriteFromBuffer())
+			return;
+	}
+}