001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hdfs.tools.offlineImageViewer;
019
020import java.io.IOException;
021import java.net.InetSocketAddress;
022import java.util.concurrent.Executors;
023
024import org.apache.commons.logging.Log;
025import org.apache.commons.logging.LogFactory;
026import org.jboss.netty.bootstrap.ServerBootstrap;
027import org.jboss.netty.channel.Channel;
028import org.jboss.netty.channel.ChannelFactory;
029import org.jboss.netty.channel.ChannelHandlerContext;
030import org.jboss.netty.channel.ChannelPipeline;
031import org.jboss.netty.channel.ChannelStateEvent;
032import org.jboss.netty.channel.Channels;
033import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
034import org.jboss.netty.channel.group.ChannelGroup;
035import org.jboss.netty.channel.group.DefaultChannelGroup;
036import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
037import org.jboss.netty.handler.codec.http.HttpRequestDecoder;
038import org.jboss.netty.handler.codec.http.HttpResponseEncoder;
039import org.jboss.netty.handler.codec.string.StringEncoder;
040
041import com.google.common.annotations.VisibleForTesting;
042
043/**
044 * WebImageViewer loads a fsimage and exposes read-only WebHDFS API for its
045 * namespace.
046 */
047public class WebImageViewer {
048  public static final Log LOG = LogFactory.getLog(WebImageViewer.class);
049
050  private Channel channel;
051  private InetSocketAddress address;
052  private final ChannelFactory factory =
053      new NioServerSocketChannelFactory(Executors.newCachedThreadPool(),
054          Executors.newCachedThreadPool(), 1);
055  private final ServerBootstrap bootstrap = new ServerBootstrap(factory);
056
057  static final ChannelGroup allChannels =
058      new DefaultChannelGroup("WebImageViewer");
059
060  public WebImageViewer(InetSocketAddress address) {
061    this.address = address;
062  }
063
064  /**
065   * Start WebImageViewer and wait until the thread is interrupted.
066   * @param fsimage the fsimage to load.
067   * @throws IOException if failed to load the fsimage.
068   */
069  public void initServerAndWait(String fsimage) throws IOException {
070    initServer(fsimage);
071    try {
072      channel.getCloseFuture().await();
073    } catch (InterruptedException e) {
074      LOG.info("Interrupted. Stopping the WebImageViewer.");
075      shutdown();
076    }
077  }
078
079  /**
080   * Start WebImageViewer.
081   * @param fsimage the fsimage to load.
082   * @throws IOException if fail to load the fsimage.
083   */
084  @VisibleForTesting
085  public void initServer(String fsimage) throws IOException {
086    FSImageLoader loader = FSImageLoader.load(fsimage);
087
088    ChannelPipeline pipeline = Channels.pipeline();
089    pipeline.addLast("channelTracker", new SimpleChannelUpstreamHandler() {
090      @Override
091      public void channelOpen(ChannelHandlerContext ctx, ChannelStateEvent e)
092          throws Exception {
093        allChannels.add(e.getChannel());
094      }
095    });
096    pipeline.addLast("httpDecoder", new HttpRequestDecoder());
097    pipeline.addLast("requestHandler", new FSImageHandler(loader));
098    pipeline.addLast("stringEncoder", new StringEncoder());
099    pipeline.addLast("httpEncoder", new HttpResponseEncoder());
100    bootstrap.setPipeline(pipeline);
101    channel = bootstrap.bind(address);
102    allChannels.add(channel);
103
104    address = (InetSocketAddress) channel.getLocalAddress();
105    LOG.info("WebImageViewer started. Listening on " + address.toString()
106        + ". Press Ctrl+C to stop the viewer.");
107  }
108
109  /**
110   * Stop WebImageViewer.
111   */
112  @VisibleForTesting
113  public void shutdown() {
114    allChannels.close().awaitUninterruptibly();
115    factory.releaseExternalResources();
116  }
117
118  /**
119   * Get the listening port.
120   * @return the port WebImageViewer is listening on
121   */
122  @VisibleForTesting
123  public int getPort() {
124    return address.getPort();
125  }
126}