hbase-rest/src/main/java/org/apache/hadoop/hbase/rest/ProtobufStreamingOutput.java

   1 /**
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18 package org.apache.hadoop.hbase.rest;
  19
  20 import java.io.IOException;
  21 import java.io.OutputStream;
  22 import java.util.List;
  23 import org.apache.hadoop.hbase.Cell;
  24 import org.apache.hadoop.hbase.CellUtil;
  25 import org.apache.hadoop.hbase.client.Result;
  26 import org.apache.hadoop.hbase.client.ResultScanner;
  27 import org.apache.hadoop.hbase.rest.model.CellModel;
  28 import org.apache.hadoop.hbase.rest.model.CellSetModel;
  29 import org.apache.hadoop.hbase.rest.model.RowModel;
  30 import org.apache.hadoop.hbase.util.Bytes;
  31 import org.apache.yetus.audience.InterfaceAudience;
  32 import org.slf4j.Logger;
  33 import org.slf4j.LoggerFactory;
  34
  35 import org.apache.hbase.thirdparty.javax.ws.rs.WebApplicationException;
  36 import org.apache.hbase.thirdparty.javax.ws.rs.core.StreamingOutput;
  37
  38 @InterfaceAudience.Private
  39 public class ProtobufStreamingOutput implements StreamingOutput {
  40   private static final Logger LOG = LoggerFactory.getLogger(ProtobufStreamingOutput.class);
  41
  42   private String contentType;
  43   private ResultScanner resultScanner;
  44   private int limit;
  45   private int fetchSize;
  46
  47   protected ProtobufStreamingOutput(ResultScanner scanner, String type, int limit, int fetchSize) {
  48     this.resultScanner = scanner;
  49     this.contentType = type;
  50     this.limit = limit;
  51     this.fetchSize = fetchSize;
  52     if (LOG.isTraceEnabled()) {
  53       LOG.trace("Created StreamingOutput with content type = " + this.contentType
  54           + " user limit : " + this.limit + " scan fetch size : " + this.fetchSize);
  55     }
  56   }
  57
  58   @Override
  59   public void write(OutputStream outStream) throws IOException, WebApplicationException {
  60     Result[] rowsToSend;
  61     if(limit < fetchSize){
  62       rowsToSend = this.resultScanner.next(limit);
  63       writeToStream(createModelFromResults(rowsToSend), this.contentType, outStream);
  64     } else {
  65       int count = limit;
  66       while (count > 0) {
  67         if (count < fetchSize) {
  68           rowsToSend = this.resultScanner.next(count);
  69         } else {
  70           rowsToSend = this.resultScanner.next(this.fetchSize);
  71         }
  72         if(rowsToSend.length == 0){
  73           break;
  74         }
  75         count = count - rowsToSend.length;
  76         writeToStream(createModelFromResults(rowsToSend), this.contentType, outStream);
  77       }
  78     }
  79   }
  80
  81   private void writeToStream(CellSetModel model, String contentType, OutputStream outStream)
  82       throws IOException {
  83     byte[] objectBytes = model.createProtobufOutput();
  84     outStream.write(Bytes.toBytes((short)objectBytes.length));
  85     outStream.write(objectBytes);
  86     outStream.flush();
  87     if (LOG.isTraceEnabled()) {
  88       LOG.trace("Wrote " + model.getRows().size() + " rows to stream successfully.");
  89     }
  90   }
  91
  92   private CellSetModel createModelFromResults(Result[] results) {
  93     CellSetModel cellSetModel = new CellSetModel();
  94     for (Result rs : results) {
  95       byte[] rowKey = rs.getRow();
  96       RowModel rModel = new RowModel(rowKey);
  97       List<Cell> kvs = rs.listCells();
  98       for (Cell kv : kvs) {
  99         rModel.addCell(new CellModel(CellUtil.cloneFamily(kv), CellUtil.cloneQualifier(kv), kv
 100             .getTimestamp(), CellUtil.cloneValue(kv)));
 101       }
 102       cellSetModel.addRow(rModel);
 103     }
 104     return cellSetModel;
 105   }
 106 }