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    • io.netty.handler.codec.memcache.binary.AbstractBinaryMemcacheDecoder Maven / Gradle / Ivy

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    This artifact provides a single jar that contains all classes required to use remote Jakarta Enterprise Beans and Jakarta Messaging, including all dependencies. It is intended for use by those not using maven, maven users should just import the Jakarta Enterprise Beans and Jakarta Messaging BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

    There is a newer version: 35.0.0.Beta1
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    /*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project 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 io.netty.handler.codec.memcache.binary;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.DecoderResult;
import io.netty.handler.codec.memcache.AbstractMemcacheObjectDecoder;
import io.netty.handler.codec.memcache.DefaultLastMemcacheContent;
import io.netty.handler.codec.memcache.DefaultMemcacheContent;
import io.netty.handler.codec.memcache.LastMemcacheContent;
import io.netty.handler.codec.memcache.MemcacheContent;
import io.netty.util.internal.UnstableApi;

import java.util.List;

/**
 * Decoder for both {@link BinaryMemcacheRequest} and {@link BinaryMemcacheResponse}.
 * 
    
 * The difference in the protocols (header) is implemented by the subclasses.
 */
@UnstableApi
public abstract class AbstractBinaryMemcacheDecoder
    extends AbstractMemcacheObjectDecoder {

    public static final int DEFAULT_MAX_CHUNK_SIZE = 8192;

    private final int chunkSize;

    private M currentMessage;
    private int alreadyReadChunkSize;

    private State state = State.READ_HEADER;

    /**
     * Create a new {@link AbstractBinaryMemcacheDecoder} with default settings.
     */
    protected AbstractBinaryMemcacheDecoder() {
        this(DEFAULT_MAX_CHUNK_SIZE);
    }

    /**
     * Create a new {@link AbstractBinaryMemcacheDecoder} with custom settings.
     *
     * @param chunkSize the maximum chunk size of the payload.
     */
    protected AbstractBinaryMemcacheDecoder(int chunkSize) {
        if (chunkSize < 0) {
            throw new IllegalArgumentException("chunkSize must be a positive integer: " + chunkSize);
        }

        this.chunkSize = chunkSize;
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception {
        switch (state) {
            case READ_HEADER: try {
                if (in.readableBytes() < 24) {
                    return;
                }
                resetDecoder();

                currentMessage = decodeHeader(in);
                state = State.READ_EXTRAS;
            } catch (Exception e) {
                resetDecoder();
                out.add(invalidMessage(e));
                return;
            }
            case READ_EXTRAS: try {
                byte extrasLength = currentMessage.extrasLength();
                if (extrasLength > 0) {
                    if (in.readableBytes() < extrasLength) {
                        return;
                    }

                    currentMessage.setExtras(in.readRetainedSlice(extrasLength));
                }

                state = State.READ_KEY;
            } catch (Exception e) {
                resetDecoder();
                out.add(invalidMessage(e));
                return;
            }
            case READ_KEY: try {
                short keyLength = currentMessage.keyLength();
                if (keyLength > 0) {
                    if (in.readableBytes() < keyLength) {
                        return;
                    }

                    currentMessage.setKey(in.readRetainedSlice(keyLength));
                }
                out.add(currentMessage.retain());
                state = State.READ_CONTENT;
            } catch (Exception e) {
                resetDecoder();
                out.add(invalidMessage(e));
                return;
            }
            case READ_CONTENT: try {
                int valueLength = currentMessage.totalBodyLength()
                    - currentMessage.keyLength()
                    - currentMessage.extrasLength();
                int toRead = in.readableBytes();
                if (valueLength > 0) {
                    if (toRead == 0) {
                        return;
                    }

                    if (toRead > chunkSize) {
                        toRead = chunkSize;
                    }

                    int remainingLength = valueLength - alreadyReadChunkSize;
                    if (toRead > remainingLength) {
                        toRead = remainingLength;
                    }

                    ByteBuf chunkBuffer = in.readRetainedSlice(toRead);

                    MemcacheContent chunk;
                    if ((alreadyReadChunkSize += toRead) >= valueLength) {
                        chunk = new DefaultLastMemcacheContent(chunkBuffer);
                    } else {
                        chunk = new DefaultMemcacheContent(chunkBuffer);
                    }

                    out.add(chunk);
                    if (alreadyReadChunkSize < valueLength) {
                        return;
                    }
                } else {
                    out.add(LastMemcacheContent.EMPTY_LAST_CONTENT);
                }

                resetDecoder();
                state = State.READ_HEADER;
                return;
            } catch (Exception e) {
                resetDecoder();
                out.add(invalidChunk(e));
                return;
            }
            case BAD_MESSAGE:
                in.skipBytes(actualReadableBytes());
                return;
            default:
                throw new Error("Unknown state reached: " + state);
        }
    }

    /**
     * Helper method to create a message indicating a invalid decoding result.
     *
     * @param cause the cause of the decoding failure.
     * @return a valid message indicating failure.
     */
    private M invalidMessage(Exception cause) {
        state = State.BAD_MESSAGE;
        M message = buildInvalidMessage();
        message.setDecoderResult(DecoderResult.failure(cause));
        return message;
    }

    /**
     * Helper method to create a content chunk indicating a invalid decoding result.
     *
     * @param cause the cause of the decoding failure.
     * @return a valid content chunk indicating failure.
     */
    private MemcacheContent invalidChunk(Exception cause) {
        state = State.BAD_MESSAGE;
        MemcacheContent chunk = new DefaultLastMemcacheContent(Unpooled.EMPTY_BUFFER);
        chunk.setDecoderResult(DecoderResult.failure(cause));
        return chunk;
    }

    /**
     * When the channel goes inactive, release all frames to prevent data leaks.
     *
     * @param ctx handler context
     * @throws Exception
     */
    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        super.channelInactive(ctx);

        resetDecoder();
    }

    /**
     * Prepare for next decoding iteration.
     */
    protected void resetDecoder() {
        if (currentMessage != null) {
            currentMessage.release();
            currentMessage = null;
        }
        alreadyReadChunkSize = 0;
    }

    /**
     * Decode and return the parsed {@link BinaryMemcacheMessage}.
     *
     * @param in the incoming buffer.
     * @return the decoded header.
     */
    protected abstract M decodeHeader(ByteBuf in);

    /**
     * Helper method to create a upstream message when the incoming parsing did fail.
     *
     * @return a message indicating a decoding failure.
     */
    protected abstract M buildInvalidMessage();

    /**
     * Contains all states this decoder can possibly be in.
     * 
    
     * Note that most of the states can be optional, the only one required is reading
     * the header ({@link #READ_HEADER}. All other steps depend on the length fields
     * in the header and will be executed conditionally.
     */
    enum State {
        /**
         * Currently reading the header portion.
         */
        READ_HEADER,

        /**
         * Currently reading the extras portion (optional).
         */
        READ_EXTRAS,

        /**
         * Currently reading the key portion (optional).
         */
        READ_KEY,

        /**
         * Currently reading the value chunks (optional).
         */
        READ_CONTENT,

        /**
         * Something went wrong while decoding the message or chunks.
         */
        BAD_MESSAGE
    }

}
    
    
    
    

    




    
    
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