db79983874
Motivation: We can replace some "hand-rolled" integer checks with our own static utility method to simplify the code. Modifications: Use methods provided by `ObjectUtil`. Result: Cleaner code and less duplication
269 lines
8.4 KiB
Java
269 lines
8.4 KiB
Java
/*
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* Copyright 2013 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.memcache.binary;
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import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.Unpooled;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.DecoderResult;
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import io.netty.handler.codec.memcache.AbstractMemcacheObjectDecoder;
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import io.netty.handler.codec.memcache.DefaultLastMemcacheContent;
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import io.netty.handler.codec.memcache.DefaultMemcacheContent;
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import io.netty.handler.codec.memcache.LastMemcacheContent;
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import io.netty.handler.codec.memcache.MemcacheContent;
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import io.netty.util.internal.UnstableApi;
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import java.util.List;
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/**
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* Decoder for both {@link BinaryMemcacheRequest} and {@link BinaryMemcacheResponse}.
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* <p/>
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* The difference in the protocols (header) is implemented by the subclasses.
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*/
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@UnstableApi
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public abstract class AbstractBinaryMemcacheDecoder<M extends BinaryMemcacheMessage>
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extends AbstractMemcacheObjectDecoder {
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public static final int DEFAULT_MAX_CHUNK_SIZE = 8192;
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private final int chunkSize;
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private M currentMessage;
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private int alreadyReadChunkSize;
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private State state = State.READ_HEADER;
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/**
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* Create a new {@link AbstractBinaryMemcacheDecoder} with default settings.
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*/
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protected AbstractBinaryMemcacheDecoder() {
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this(DEFAULT_MAX_CHUNK_SIZE);
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}
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/**
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* Create a new {@link AbstractBinaryMemcacheDecoder} with custom settings.
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*
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* @param chunkSize the maximum chunk size of the payload.
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*/
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protected AbstractBinaryMemcacheDecoder(int chunkSize) {
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checkPositiveOrZero(chunkSize, "chunkSize");
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this.chunkSize = chunkSize;
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}
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@Override
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protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
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switch (state) {
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case READ_HEADER: try {
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if (in.readableBytes() < 24) {
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return;
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}
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resetDecoder();
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currentMessage = decodeHeader(in);
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state = State.READ_EXTRAS;
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} catch (Exception e) {
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resetDecoder();
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out.add(invalidMessage(e));
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return;
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}
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case READ_EXTRAS: try {
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byte extrasLength = currentMessage.extrasLength();
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if (extrasLength > 0) {
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if (in.readableBytes() < extrasLength) {
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return;
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}
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currentMessage.setExtras(in.readRetainedSlice(extrasLength));
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}
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state = State.READ_KEY;
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} catch (Exception e) {
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resetDecoder();
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out.add(invalidMessage(e));
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return;
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}
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case READ_KEY: try {
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short keyLength = currentMessage.keyLength();
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if (keyLength > 0) {
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if (in.readableBytes() < keyLength) {
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return;
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}
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currentMessage.setKey(in.readRetainedSlice(keyLength));
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}
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out.add(currentMessage.retain());
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state = State.READ_CONTENT;
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} catch (Exception e) {
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resetDecoder();
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out.add(invalidMessage(e));
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return;
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}
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case READ_CONTENT: try {
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int valueLength = currentMessage.totalBodyLength()
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- currentMessage.keyLength()
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- currentMessage.extrasLength();
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int toRead = in.readableBytes();
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if (valueLength > 0) {
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if (toRead == 0) {
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return;
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}
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if (toRead > chunkSize) {
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toRead = chunkSize;
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}
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int remainingLength = valueLength - alreadyReadChunkSize;
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if (toRead > remainingLength) {
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toRead = remainingLength;
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}
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ByteBuf chunkBuffer = in.readRetainedSlice(toRead);
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MemcacheContent chunk;
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if ((alreadyReadChunkSize += toRead) >= valueLength) {
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chunk = new DefaultLastMemcacheContent(chunkBuffer);
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} else {
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chunk = new DefaultMemcacheContent(chunkBuffer);
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}
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out.add(chunk);
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if (alreadyReadChunkSize < valueLength) {
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return;
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}
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} else {
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out.add(LastMemcacheContent.EMPTY_LAST_CONTENT);
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}
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resetDecoder();
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state = State.READ_HEADER;
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return;
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} catch (Exception e) {
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resetDecoder();
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out.add(invalidChunk(e));
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return;
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}
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case BAD_MESSAGE:
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in.skipBytes(actualReadableBytes());
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return;
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default:
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throw new Error("Unknown state reached: " + state);
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}
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}
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/**
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* Helper method to create a message indicating a invalid decoding result.
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*
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* @param cause the cause of the decoding failure.
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* @return a valid message indicating failure.
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*/
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private M invalidMessage(Exception cause) {
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state = State.BAD_MESSAGE;
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M message = buildInvalidMessage();
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message.setDecoderResult(DecoderResult.failure(cause));
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return message;
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}
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/**
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* Helper method to create a content chunk indicating a invalid decoding result.
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*
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* @param cause the cause of the decoding failure.
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* @return a valid content chunk indicating failure.
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*/
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private MemcacheContent invalidChunk(Exception cause) {
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state = State.BAD_MESSAGE;
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MemcacheContent chunk = new DefaultLastMemcacheContent(Unpooled.EMPTY_BUFFER);
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chunk.setDecoderResult(DecoderResult.failure(cause));
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return chunk;
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}
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/**
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* When the channel goes inactive, release all frames to prevent data leaks.
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*
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* @param ctx handler context
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* @throws Exception
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*/
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@Override
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public void channelInactive(ChannelHandlerContext ctx) throws Exception {
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super.channelInactive(ctx);
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resetDecoder();
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}
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/**
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* Prepare for next decoding iteration.
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*/
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protected void resetDecoder() {
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if (currentMessage != null) {
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currentMessage.release();
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currentMessage = null;
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}
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alreadyReadChunkSize = 0;
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}
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/**
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* Decode and return the parsed {@link BinaryMemcacheMessage}.
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*
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* @param in the incoming buffer.
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* @return the decoded header.
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*/
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protected abstract M decodeHeader(ByteBuf in);
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/**
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* Helper method to create a upstream message when the incoming parsing did fail.
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*
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* @return a message indicating a decoding failure.
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*/
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protected abstract M buildInvalidMessage();
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/**
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* Contains all states this decoder can possibly be in.
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* <p/>
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* Note that most of the states can be optional, the only one required is reading
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* the header ({@link #READ_HEADER}. All other steps depend on the length fields
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* in the header and will be executed conditionally.
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*/
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enum State {
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/**
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* Currently reading the header portion.
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*/
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READ_HEADER,
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/**
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* Currently reading the extras portion (optional).
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*/
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READ_EXTRAS,
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/**
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* Currently reading the key portion (optional).
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*/
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READ_KEY,
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/**
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* Currently reading the value chunks (optional).
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*/
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READ_CONTENT,
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/**
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* Something went wrong while decoding the message or chunks.
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*/
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BAD_MESSAGE
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}
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}
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