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     */
018    package org.apache.hadoop.hdfs.tools.offlineImageViewer;
019    
020    import java.io.IOException;
021    import java.net.InetSocketAddress;
022    import java.util.concurrent.Executors;
023    
024    import org.apache.commons.logging.Log;
025    import org.apache.commons.logging.LogFactory;
026    import org.jboss.netty.bootstrap.ServerBootstrap;
027    import org.jboss.netty.channel.Channel;
028    import org.jboss.netty.channel.ChannelFactory;
029    import org.jboss.netty.channel.ChannelHandlerContext;
030    import org.jboss.netty.channel.ChannelPipeline;
031    import org.jboss.netty.channel.ChannelStateEvent;
032    import org.jboss.netty.channel.Channels;
033    import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
034    import org.jboss.netty.channel.group.ChannelGroup;
035    import org.jboss.netty.channel.group.DefaultChannelGroup;
036    import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
037    import org.jboss.netty.handler.codec.http.HttpRequestDecoder;
038    import org.jboss.netty.handler.codec.http.HttpResponseEncoder;
039    import org.jboss.netty.handler.codec.string.StringEncoder;
040    
041    import com.google.common.annotations.VisibleForTesting;
042    
043    /**
044     * WebImageViewer loads a fsimage and exposes read-only WebHDFS API for its
045     * namespace.
046     */
047    public 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    }