netty5/transport/src/main/java/io/netty/bootstrap/ServerBootstrap.java

/*
 * 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:
 *
 *   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.bootstrap;

import io.netty.channel.Channel;
import io.netty.channel.ChannelConfig;
import io.netty.channel.ChannelException;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoop;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.ServerChannel;
import io.netty.channel.socket.SocketChannel;
import io.netty.util.AttributeKey;
import io.netty.util.concurrent.EventExecutorGroup;
import io.netty.util.internal.StringUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.lang.reflect.Constructor;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.TimeUnit;

/**
 * {@link Bootstrap} sub-class which allows easy bootstrap of {@link ServerChannel}
 *
 */
public final class ServerBootstrap extends AbstractBootstrap<ServerBootstrap, ServerChannel> {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(ServerBootstrap.class);

    private volatile ServerChannelFactory<? extends ServerChannel> channelFactory;
    private final Map<ChannelOption<?>, Object> childOptions = new LinkedHashMap<ChannelOption<?>, Object>();
    private final Map<AttributeKey<?>, Object> childAttrs = new LinkedHashMap<AttributeKey<?>, Object>();
    private volatile EventLoopGroup childGroup;
    private volatile ChannelHandler childHandler;

    public ServerBootstrap() { }

    private ServerBootstrap(ServerBootstrap bootstrap) {
        super(bootstrap);
        channelFactory = bootstrap.channelFactory;
        childGroup = bootstrap.childGroup;
        childHandler = bootstrap.childHandler;
        synchronized (bootstrap.childOptions) {
            childOptions.putAll(bootstrap.childOptions);
        }
        synchronized (bootstrap.childAttrs) {
            childAttrs.putAll(bootstrap.childAttrs);
        }
    }

    /**
     * The {@link Class} which is used to create {@link Channel} instances from.
     * You either use this or {@link #channelFactory(ServerChannelFactory)} if your
     * {@link Channel} implementation has no no-args constructor.
     */
    public ServerBootstrap channel(Class<? extends ServerChannel> channelClass) {
        if (channelClass == null) {
            throw new NullPointerException("channelClass");
        }
        return channelFactory(new ServerBootstrapChannelFactory<ServerChannel>(channelClass));
    }

    /**
     * {@link ChannelFactory} which is used to create {@link Channel} instances from
     * when calling {@link #bind()}. This method is usually only used if {@link #channel(Class)}
     * is not working for you because of some more complex needs. If your {@link Channel} implementation
     * has a no-args constructor, its highly recommend to just use {@link #channel(Class)} for
     * simplify your code.
     */
    public ServerBootstrap channelFactory(ServerChannelFactory<? extends ServerChannel> channelFactory) {
        if (channelFactory == null) {
            throw new NullPointerException("channelFactory");
        }
        if (this.channelFactory != null) {
            throw new IllegalStateException("channelFactory set already");
        }

        this.channelFactory = channelFactory;
        return this;
    }

    @Override
    Channel createChannel() {
        EventLoop eventLoop = group().next();
        return channelFactory().newChannel(eventLoop, childGroup);
    }

    ServerChannelFactory<? extends ServerChannel> channelFactory() {
        return channelFactory;
    }

    /**
     * Specify the {@link EventLoopGroup} which is used for the parent (acceptor) and the child (client).
     */
    @Override
    public ServerBootstrap group(EventLoopGroup group) {
        return group(group, group);
    }

    /**
     * Set the {@link EventExecutorGroup} for the parent (acceptor) and the child (client). These
     * {@link EventExecutorGroup}'s are used to handle all the events and IO for {@link SocketChannel} and
     * {@link Channel}'s.
     */
    public ServerBootstrap group(EventLoopGroup parentGroup, EventLoopGroup childGroup) {
        super.group(parentGroup);
        if (childGroup == null) {
            throw new NullPointerException("childGroup");
        }
        if (this.childGroup != null) {
            throw new IllegalStateException("childGroup set already");
        }
        this.childGroup = childGroup;
        return this;
    }

    /**
     * Allow to specify a {@link ChannelOption} which is used for the {@link Channel} instances once they get created
     * (after the acceptor accepted the {@link Channel}). Use a value of {@code null} to remove a previous set
     * {@link ChannelOption}.
     */
    public <T> ServerBootstrap childOption(ChannelOption<T> childOption, T value) {
        if (childOption == null) {
            throw new NullPointerException("childOption");
        }
        if (value == null) {
            synchronized (childOptions) {
                childOptions.remove(childOption);
            }
        } else {
            synchronized (childOptions) {
                childOptions.put(childOption, value);
            }
        }
        return this;
    }

    /**
     * Set the specific {@link AttributeKey} with the given value on every child {@link Channel}. If the value is
     * {@code null} the {@link AttributeKey} is removed
     */
    public <T> ServerBootstrap childAttr(AttributeKey<T> childKey, T value) {
        if (childKey == null) {
            throw new NullPointerException("childKey");
        }
        if (value == null) {
            childAttrs.remove(childKey);
        } else {
            childAttrs.put(childKey, value);
        }
        return this;
    }

    /**
     * Set the {@link ChannelHandler} which is used to serve the request for the {@link Channel}'s.
     */
    public ServerBootstrap childHandler(ChannelHandler childHandler) {
        if (childHandler == null) {
            throw new NullPointerException("childHandler");
        }
        this.childHandler = childHandler;
        return this;
    }

    /**
     * Return the configured {@link EventLoopGroup} which will be used for the child channels or {@code null}
     * if non is configured yet.
     */
    public EventLoopGroup childGroup() {
        return childGroup;
    }

    @Override
    void init(Channel channel) throws Exception {
        final Map<ChannelOption<?>, Object> options = options();
        synchronized (options) {
            channel.config().setOptions(options);
        }

        final Map<AttributeKey<?>, Object> attrs = attrs();
        synchronized (attrs) {
            for (Entry<AttributeKey<?>, Object> e: attrs.entrySet()) {
                @SuppressWarnings("unchecked")
                AttributeKey<Object> key = (AttributeKey<Object>) e.getKey();
                channel.attr(key).set(e.getValue());
            }
        }

        ChannelPipeline p = channel.pipeline();
        if (handler() != null) {
            p.addLast(handler());
        }

        final ChannelHandler currentChildHandler = childHandler;
        final Entry<ChannelOption<?>, Object>[] currentChildOptions;
        final Entry<AttributeKey<?>, Object>[] currentChildAttrs;
        synchronized (childOptions) {
            currentChildOptions = childOptions.entrySet().toArray(newOptionArray(childOptions.size()));
        }
        synchronized (childAttrs) {
            currentChildAttrs = childAttrs.entrySet().toArray(newAttrArray(childAttrs.size()));
        }

        p.addLast(new ChannelInitializer<Channel>() {
            @Override
            public void initChannel(Channel ch) throws Exception {
                ch.pipeline().addLast(new ServerBootstrapAcceptor(currentChildHandler, currentChildOptions,
                        currentChildAttrs));
            }
        });
    }

    @Override
    public ServerBootstrap validate() {
        super.validate();
        if (childHandler == null) {
            throw new IllegalStateException("childHandler not set");
        }
        if (childGroup == null) {
            logger.warn("childGroup is not set. Using parentGroup instead.");
            childGroup = group();
        }
        return this;
    }

    @SuppressWarnings("unchecked")
    private static Entry<ChannelOption<?>, Object>[] newOptionArray(int size) {
        return new Entry[size];
    }

    @SuppressWarnings("unchecked")
    private static Entry<AttributeKey<?>, Object>[] newAttrArray(int size) {
        return new Entry[size];
    }

    private static class ServerBootstrapAcceptor extends ChannelHandlerAdapter {

        private final ChannelHandler childHandler;
        private final Entry<ChannelOption<?>, Object>[] childOptions;
        private final Entry<AttributeKey<?>, Object>[] childAttrs;

        ServerBootstrapAcceptor(ChannelHandler childHandler, Entry<ChannelOption<?>, Object>[] childOptions,
                Entry<AttributeKey<?>, Object>[] childAttrs) {
            this.childHandler = childHandler;
            this.childOptions = childOptions;
            this.childAttrs = childAttrs;
        }

        @Override
        @SuppressWarnings("unchecked")
        public void channelRead(ChannelHandlerContext ctx, Object msg) {
            Channel child = (Channel) msg;

            child.pipeline().addLast(childHandler);

            for (Entry<ChannelOption<?>, Object> e: childOptions) {
                try {
                    if (!child.config().setOption((ChannelOption<Object>) e.getKey(), e.getValue())) {
                        logger.warn("Unknown channel option: " + e);
                    }
                } catch (Throwable t) {
                    logger.warn("Failed to set a channel option: " + child, t);
                }
            }

            for (Entry<AttributeKey<?>, Object> e: childAttrs) {
                child.attr((AttributeKey<Object>) e.getKey()).set(e.getValue());
            }

            child.unsafe().register(child.newPromise());
        }

        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            final ChannelConfig config = ctx.channel().config();
            if (config.isAutoRead()) {
                // stop accept new connections for 1 second to allow the channel to recover
                // See https://github.com/netty/netty/issues/1328
                config.setAutoRead(false);
                ctx.channel().eventLoop().schedule(new Runnable() {
                    @Override
                    public void run() {
                       config.setAutoRead(true);
                    }
                }, 1, TimeUnit.SECONDS);
            }
            // still let the exceptionCaught event flow through the pipeline to give the user
            // a chance to do something with it
            ctx.fireExceptionCaught(cause);
        }
    }

    @Override
    @SuppressWarnings("CloneDoesntCallSuperClone")
    public ServerBootstrap clone() {
        return new ServerBootstrap(this);
    }

    @Override
    public String toString() {
        StringBuilder buf = new StringBuilder(super.toString());
        buf.setLength(buf.length() - 1);
        buf.append(", ");
        if (childGroup != null) {
            buf.append("childGroup: ");
            buf.append(StringUtil.simpleClassName(childGroup));
            buf.append(", ");
        }
        synchronized (childOptions) {
            if (!childOptions.isEmpty()) {
                buf.append("childOptions: ");
                buf.append(childOptions);
                buf.append(", ");
            }
        }
        synchronized (childAttrs) {
            if (!childAttrs.isEmpty()) {
                buf.append("childAttrs: ");
                buf.append(childAttrs);
                buf.append(", ");
            }
        }
        if (childHandler != null) {
            buf.append("childHandler: ");
            buf.append(childHandler);
            buf.append(", ");
        }
        if (buf.charAt(buf.length() - 1) == '(') {
            buf.append(')');
        } else {
            buf.setCharAt(buf.length() - 2, ')');
            buf.setLength(buf.length() - 1);
        }

        return buf.toString();
    }

    private static final class ServerBootstrapChannelFactory<T extends ServerChannel>
            implements ServerChannelFactory<T> {

        private final Class<? extends T> clazz;

        ServerBootstrapChannelFactory(Class<? extends T> clazz) {
            this.clazz = clazz;
        }

        @Override
        public T newChannel(EventLoop eventLoop, EventLoopGroup childGroup) {
            try {
                Constructor<? extends T> constructor = clazz.getConstructor(EventLoop.class, EventLoopGroup.class);
                return constructor.newInstance(eventLoop, childGroup);
            } catch (Throwable t) {
                throw new ChannelException("Unable to create Channel from class " + clazz, t);
            }
        }

        @Override
        public String toString() {
            return StringUtil.simpleClassName(clazz) + ".class";
        }
    }
}