MessageAggregator.java — netty Source File

Source Code

/*
 * Copyright 2012 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:
 *
 *   https://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;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufHolder;
import io.netty.buffer.CompositeByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.util.ReferenceCountUtil;

import java.util.List;

import static io.netty.buffer.Unpooled.EMPTY_BUFFER;
import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;

/**
 * An abstract {@link ChannelHandler} that aggregates a series of message objects into a single aggregated message.
 * <p>
 * 'A series of messages' is composed of the following:
 * <ul>
 * <li>a single start message which optionally contains the first part of the content, and</li>
 * <li>1 or more content messages.</li>
 * </ul>
 * The content of the aggregated message will be the merged content of the start message and its following content
 * messages. If this aggregator encounters a content message where {@link #isLastContentMessage(ByteBufHolder)}
 * return {@code true} for, the aggregator will finish the aggregation and produce the aggregated message and expect
 * another start message.
 * </p>
 *
 * @param <I> the type that covers both start message and content message
 * @param <S> the type of the start message
 * @param <C> the type of the content message (must be a subtype of {@link ByteBufHolder})
 * @param <O> the type of the aggregated message (must be a subtype of {@code S} and {@link ByteBufHolder})
 */
public abstract class MessageAggregator<I, S, C extends ByteBufHolder, O extends ByteBufHolder>
        extends MessageToMessageDecoder<I> {

    private static final int DEFAULT_MAX_COMPOSITEBUFFER_COMPONENTS = 1024;

    private final int maxContentLength;
    private O currentMessage;
    private boolean handlingOversizedMessage;

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