Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/incubator-flink/pull/254#discussion_r21539247
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/io/network/netty/NettyMessage.java
---
@@ -0,0 +1,451 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.io.network.netty;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelOutboundHandlerAdapter;
+import io.netty.channel.ChannelPromise;
+import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
+import io.netty.handler.codec.MessageToMessageDecoder;
+import org.apache.flink.runtime.event.task.TaskEvent;
+import
org.apache.flink.runtime.io.network.api.serialization.EventSerializer;
+import org.apache.flink.runtime.io.network.buffer.Buffer;
+import
org.apache.flink.runtime.io.network.partition.consumer.InputChannelID;
+import org.apache.flink.runtime.jobgraph.IntermediateResultPartitionID;
+import org.apache.flink.util.InstantiationUtil;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+
+/**
+ * A simple and generic interface to serialize messages to Netty's buffer
space.
+ */
+interface NettyMessage {
+
+ //
------------------------------------------------------------------------
+ // Note: Every NettyMessage subtype needs to have a public 0-argument
+ // constructor in order to work with the generic deserializer.
+ //
------------------------------------------------------------------------
+
+ byte getId();
+
+ int getLength();
+
+ void writeTo(ByteBuf outboundBuffer);
+
+ void readFrom(ByteBuf inboundBuffer) throws Exception;
+
+ interface ClientRequest extends NettyMessage {
+
+ InputChannelID getReceiverId();
+
+ }
+
+ //
------------------------------------------------------------------------
+ // Generic NettyMessage encoder and decoder
+ //
------------------------------------------------------------------------
+
+ @ChannelHandler.Sharable
+ static class NettyMessageEncoder extends ChannelOutboundHandlerAdapter {
+
+ static final int HEADER_LENGTH = 4 + 4 + 1; // frame length
(4), magic number (4), msg ID (1)
+
+ static final int MAGIC_NUMBER = 0xBADC0FFE;
+
+ @Override
+ public void write(ChannelHandlerContext ctx, Object msg,
ChannelPromise promise) throws Exception {
+ if (msg instanceof NettyMessage) {
+ try {
+ NettyMessage nettyMsg = (NettyMessage)
msg;
+ // frame length (4), magic number (4),
message id (1), message (var length)
+ int frameLength = 4 + 4 + 1 +
nettyMsg.getLength();
+
+ final ByteBuf outboundBuffer =
ctx.alloc().directBuffer(frameLength);
+
+ outboundBuffer.writeInt(frameLength);
+ outboundBuffer.writeInt(MAGIC_NUMBER);
+
outboundBuffer.writeByte(nettyMsg.getId());
+ nettyMsg.writeTo(outboundBuffer);
+
+ ctx.write(outboundBuffer, promise);
+ }
+ catch (Throwable t) {
+ throw new IOException("Error while
serializing message: " + msg, t);
+ }
+ }
+ else {
+ ctx.write(msg, promise);
+ }
+ }
+
+ // Create the frame length decoder here as it depends on the
encoder
+ static LengthFieldBasedFrameDecoder createFrameLengthDecoder() {
+ return new
LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, -4, 4);
+ }
+ }
+
+ @ChannelHandler.Sharable
+ static class NettyMessageDecoder extends
MessageToMessageDecoder<ByteBuf> {
+
+ @Override
+ protected void decode(ChannelHandlerContext ctx, ByteBuf msg,
List<Object> out) throws Exception {
+ int magicNumber = msg.readInt();
+
+ if (magicNumber != NettyMessageEncoder.MAGIC_NUMBER) {
+ throw new IllegalStateException("Network stream
corrupted: received incorrect magic number.");
+ }
+
+ byte msgId = msg.readByte();
+
+ NettyMessage decodedMsg = null;
+
+ if (msgId == BufferResponse.ID) {
+ decodedMsg = new BufferResponse();
+ }
+ else if (msgId == PartitionRequest.ID) {
+ decodedMsg = new PartitionRequest();
+ }
+ else if (msgId == TaskEventRequest.ID) {
+ decodedMsg = new TaskEventRequest();
+ }
+ else if (msgId == ErrorResponse.ID) {
+ decodedMsg = new ErrorResponse();
+ }
+ else {
+ // Exception: unknown message
--- End diff --
Really throw an exception here? ;-)
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