org.apache.hadoop.hdfs.tools.offlineImageViewer.WebImageViewer.java Source code

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Here is the source code for org.apache.hadoop.hdfs.tools.offlineImageViewer.WebImageViewer.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.tools.offlineImageViewer;

import com.google.common.annotations.VisibleForTesting;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpRequestDecoder;
import io.netty.handler.codec.http.HttpResponseEncoder;
import io.netty.handler.codec.string.StringEncoder;
import io.netty.util.concurrent.GlobalEventExecutor;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.Closeable;
import java.io.IOException;
import java.net.InetSocketAddress;

/**
 * WebImageViewer loads a fsimage and exposes read-only WebHDFS API for its
 * namespace.
 */
public class WebImageViewer implements Closeable {
    public static final Log LOG = LogFactory.getLog(WebImageViewer.class);

    private Channel channel;
    private InetSocketAddress address;

    private final ServerBootstrap bootstrap;
    private final EventLoopGroup bossGroup;
    private final EventLoopGroup workerGroup;
    private final ChannelGroup allChannels;

    public WebImageViewer(InetSocketAddress address) {
        this.address = address;
        this.bossGroup = new NioEventLoopGroup();
        this.workerGroup = new NioEventLoopGroup();
        this.allChannels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
        this.bootstrap = new ServerBootstrap().group(bossGroup, workerGroup).channel(NioServerSocketChannel.class);
    }

    /**
     * Start WebImageViewer and wait until the thread is interrupted.
     * @param fsimage the fsimage to load.
     * @throws IOException if failed to load the fsimage.
     */
    public void start(String fsimage) throws IOException {
        try {
            initServer(fsimage);
            channel.closeFuture().await();
        } catch (InterruptedException e) {
            LOG.info("Interrupted. Stopping the WebImageViewer.");
            close();
        }
    }

    /**
     * Start WebImageViewer.
     * @param fsimage the fsimage to load.
     * @throws IOException if fail to load the fsimage.
     */
    @VisibleForTesting
    public void initServer(String fsimage) throws IOException, InterruptedException {
        final FSImageLoader loader = FSImageLoader.load(fsimage);

        bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
            @Override
            protected void initChannel(SocketChannel ch) throws Exception {
                ChannelPipeline p = ch.pipeline();
                p.addLast(new HttpRequestDecoder(), new StringEncoder(), new HttpResponseEncoder(),
                        new FSImageHandler(loader, allChannels));
            }
        });

        channel = bootstrap.bind(address).sync().channel();
        allChannels.add(channel);

        address = (InetSocketAddress) channel.localAddress();
        LOG.info("WebImageViewer started. Listening on " + address.toString()
                + ". Press Ctrl+C to stop the viewer.");
    }

    /**
     * Get the listening port.
     * @return the port WebImageViewer is listening on
     */
    @VisibleForTesting
    public int getPort() {
        return address.getPort();
    }

    @Override
    public void close() {
        allChannels.close().awaitUninterruptibly();
        bossGroup.shutdownGracefully();
        workerGroup.shutdownGracefully();
    }
}