hbase-server/src/test/java/org/apache/hadoop/hbase/client/BufferingScanResultConsumer.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.client;
  19
  20 import org.apache.hbase.thirdparty.com.google.common.base.Throwables;
  21
  22 import java.io.IOException;
  23 import java.util.ArrayDeque;
  24 import java.util.Queue;
  25
  26 import org.apache.hadoop.hbase.client.metrics.ScanMetrics;
  27
  28 /**
  29  * A scan result consumer which buffers all the data in memory and you can call the {@link #take()}
  30  * method below to get the result one by one. Should only be used by tests, do not write production
  31  * code like this as the buffer is unlimited and may cause OOM.
  32  */
  33 class BufferingScanResultConsumer implements AdvancedScanResultConsumer {
  34
  35   private ScanMetrics scanMetrics;
  36
  37   private final Queue<Result> queue = new ArrayDeque<>();
  38
  39   private boolean finished;
  40
  41   private Throwable error;
  42
  43   @Override
  44   public void onScanMetricsCreated(ScanMetrics scanMetrics) {
  45     this.scanMetrics = scanMetrics;
  46   }
  47
  48   @Override
  49   public synchronized void onNext(Result[] results, ScanController controller) {
  50     for (Result result : results) {
  51       queue.offer(result);
  52     }
  53     notifyAll();
  54   }
  55
  56   @Override
  57   public synchronized void onError(Throwable error) {
  58     finished = true;
  59     this.error = error;
  60     notifyAll();
  61   }
  62
  63   @Override
  64   public synchronized void onComplete() {
  65     finished = true;
  66     notifyAll();
  67   }
  68
  69   public synchronized Result take() throws IOException, InterruptedException {
  70     for (;;) {
  71       if (!queue.isEmpty()) {
  72         return queue.poll();
  73       }
  74       if (finished) {
  75         if (error != null) {
  76           Throwables.propagateIfPossible(error, IOException.class);
  77           throw new IOException(error);
  78         } else {
  79           return null;
  80         }
  81       }
  82       wait();
  83     }
  84   }
  85
  86   public ScanMetrics getScanMetrics() {
  87     return scanMetrics;
  88   }
  89 }