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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.omid.tso;
19  
20  import org.apache.omid.metrics.MetricsRegistry;
21  import org.apache.omid.timestamp.storage.TimestampStorage;
22  import org.slf4j.Logger;
23  import org.slf4j.LoggerFactory;
24  
25  import javax.inject.Inject;
26  import java.io.IOException;
27  
28  public class PausableTimestampOracle extends TimestampOracleImpl {
29  
30      private static final Logger LOG = LoggerFactory.getLogger(PausableTimestampOracle.class);
31  
32      private volatile boolean tsoPaused = false;
33  
34      @Inject
35      public PausableTimestampOracle(MetricsRegistry metrics,
36                                     TimestampStorage tsStorage,
37                                     Panicker panicker) throws IOException {
38          super(metrics, tsStorage, panicker);
39      }
40  
41      @Override
42      public long next() throws IOException {
43          while (tsoPaused) {
44              synchronized (this) {
45                  try {
46                      this.wait();
47                  } catch (InterruptedException e) {
48                      LOG.error("Interrupted whilst paused");
49                      Thread.currentThread().interrupt();
50                  }
51              }
52          }
53          return super.next();
54      }
55  
56      public synchronized void pause() {
57          tsoPaused = true;
58          this.notifyAll();
59      }
60  
61      public synchronized void resume() {
62          tsoPaused = false;
63          this.notifyAll();
64      }
65  
66      public boolean isTSOPaused() {
67          return tsoPaused;
68      }
69  
70  }