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.server.datanode.web.resources;
019    
020    import java.io.IOException;
021    import java.io.OutputStream;
022    import java.lang.annotation.Annotation;
023    import java.lang.reflect.Type;
024    
025    import javax.ws.rs.core.MediaType;
026    import javax.ws.rs.core.MultivaluedMap;
027    import javax.ws.rs.ext.MessageBodyWriter;
028    import javax.ws.rs.ext.Provider;
029    
030    import org.apache.hadoop.hdfs.DFSClient;
031    import org.apache.hadoop.hdfs.client.HdfsDataInputStream;
032    import org.apache.hadoop.io.IOUtils;
033    
034    /**
035     * A response entity for a HdfsDataInputStream.
036     */
037    public class OpenEntity {
038      private final HdfsDataInputStream in;
039      private final long length;
040      private final int outBufferSize;
041      private final DFSClient dfsclient;
042      
043      OpenEntity(final HdfsDataInputStream in, final long length,
044          final int outBufferSize, final DFSClient dfsclient) {
045        this.in = in;
046        this.length = length;
047        this.outBufferSize = outBufferSize;
048        this.dfsclient = dfsclient;
049      }
050      
051      /**
052       * A {@link MessageBodyWriter} for {@link OpenEntity}.
053       */
054      @Provider
055      public static class Writer implements MessageBodyWriter<OpenEntity> {
056    
057        @Override
058        public boolean isWriteable(Class<?> clazz, Type genericType,
059            Annotation[] annotations, MediaType mediaType) {
060          return clazz == OpenEntity.class
061              && MediaType.APPLICATION_OCTET_STREAM_TYPE.isCompatible(mediaType);
062        }
063    
064        @Override
065        public long getSize(OpenEntity e, Class<?> type, Type genericType,
066            Annotation[] annotations, MediaType mediaType) {
067          return e.length;
068        }
069    
070        @Override
071        public void writeTo(OpenEntity e, Class<?> type, Type genericType,
072            Annotation[] annotations, MediaType mediaType,
073            MultivaluedMap<String, Object> httpHeaders, OutputStream out
074            ) throws IOException {
075          try {
076            byte[] buf = new byte[e.outBufferSize];
077            long remaining = e.length;
078            while (remaining > 0) {
079              int read = e.in.read(buf, 0, (int)Math.min(buf.length, remaining));
080              if (read == -1) { // EOF
081                break;
082              }
083              out.write(buf, 0, read);
084              out.flush();
085              remaining -= read;
086            }
087          } finally {
088            IOUtils.cleanup(DatanodeWebHdfsMethods.LOG, e.in);
089            IOUtils.cleanup(DatanodeWebHdfsMethods.LOG, e.dfsclient);
090          }
091        }
092      }
093    }