ChannelInitializer.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.channel;

import io.netty.bootstrap.Bootstrap;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.util.Collections;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * A special {@link ChannelInboundHandler} which offers an easy way to initialize a {@link Channel} once it was
 * registered to its {@link EventLoop}.
 *
 * Implementations are most often used in the context of {@link Bootstrap#handler(ChannelHandler)} ,
 * {@link ServerBootstrap#handler(ChannelHandler)} and {@link ServerBootstrap#childHandler(ChannelHandler)} to
 * setup the {@link ChannelPipeline} of a {@link Channel}.
 *
 * <pre>
 *
 * public class MyChannelInitializer extends {@link ChannelInitializer} {
 *     public void initChannel({@link Channel} channel) {
 *         channel.pipeline().addLast("myHandler", new MyHandler());
 *     }
 * }
 *
 * {@link ServerBootstrap} bootstrap = ...;
 * ...
 * bootstrap.childHandler(new MyChannelInitializer());
 * ...
 * </pre>
 * Be aware that this class is marked as {@link Sharable} and so the implementation must be safe to be re-used.
 *
 * @param <C>   A sub-type of {@link Channel}
 */
@Sharable
public abstract class ChannelInitializer<C extends Channel> extends ChannelInboundHandlerAdapter {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(ChannelInitializer.class);
    // We use a Set as a ChannelInitializer is usually shared between all Channels in a Bootstrap /
    // ServerBootstrap. This way we can reduce the memory usage compared to use Attributes.
    private final Set<ChannelHandlerContext> initMap = ConcurrentHashMap.newKeySet();

// ... (99 more lines)