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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.hadoop.hbase.master;
19  
20  import org.apache.hadoop.classification.InterfaceAudience;
21  import org.apache.hadoop.classification.InterfaceStability;
22  import org.apache.hadoop.hbase.errorhandling.ForeignException;
23  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
24  
25  /**
26   * Watch the current snapshot under process
27   */
28  @InterfaceAudience.Private
29  @InterfaceStability.Unstable
30  public interface SnapshotSentinel {
31  
32    /**
33     * Check to see if the snapshot is finished, where finished may be success or failure.
34     * @return <tt>false</tt> if the snapshot is still in progress, <tt>true</tt> if the snapshot has
35     *         finished
36     */
37    boolean isFinished();
38  
39    /**
40     * @return -1 if the snapshot is in progress, otherwise the completion timestamp.
41     */
42    long getCompletionTimestamp();
43  
44    /**
45     * Actively cancel a running snapshot.
46     * @param why Reason for cancellation.
47     */
48    void cancel(String why);
49  
50    /**
51     * @return the description of the snapshot being run
52     */
53    SnapshotDescription getSnapshot();
54  
55    /**
56     * Get the exception that caused the snapshot to fail, if the snapshot has failed.
57     * @return {@link ForeignException} that caused the snapshot to fail, or <tt>null</tt> if the
58     *  snapshot is still in progress or has succeeded
59     */
60    ForeignException getExceptionIfFailed();
61  
62    /**
63     * Rethrow the exception returned by {@link SnapshotSentinel#getExceptionIfFailed}.
64     * If there is no exception this is a no-op.
65     *
66     * @throws ForeignException all exceptions from remote sources are procedure exceptions
67     */
68    void rethrowExceptionIfFailed() throws ForeignException;
69  }