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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.procedure;
19  
20  import java.io.IOException;
21  
22  import org.apache.hadoop.classification.InterfaceAudience;
23  import org.apache.hadoop.classification.InterfaceStability;
24  import org.apache.hadoop.hbase.Stoppable;
25  import org.apache.hadoop.hbase.master.MasterServices;
26  import org.apache.hadoop.hbase.master.MetricsMaster;
27  import org.apache.hadoop.hbase.master.HMaster;
28  import org.apache.hadoop.hbase.master.snapshot.SnapshotManager;
29  import org.apache.hadoop.hbase.regionserver.HRegionServer;
30  import org.apache.hadoop.hbase.regionserver.snapshot.RegionServerSnapshotManager;
31  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.ProcedureDescription;
32  import org.apache.zookeeper.KeeperException;
33  
34  /**
35  * A life-cycle management interface for globally barriered procedures on master.
36  * See the following doc on details of globally barriered procedure:
37  * https://issues.apache.org/jira/secure/attachment/12555103/121127-global-barrier-proc.pdf
38  *
39  * To implement a custom globally barriered procedure, user needs to extend two classes:
40  * {@link MasterProcedureManager} and {@link RegionServerProcedureManager}. Implementation of
41  * {@link MasterProcedureManager} is loaded into {@link HMaster} process via configuration
42  * parameter 'hbase.procedure.master.classes', while implementation of
43  * {@link RegionServerProcedureManager} is loaded into {@link HRegionServer} process via
44  * configuration parameter 'hbase.procedure.regionserver.classes'.
45  *
46  * An example of globally barriered procedure implementation is {@link SnapshotManager} and
47  * {@link RegionServerSnapshotManager}.
48  *
49  * A globally barriered procedure is identified by its signature (usually it is the name of the
50  * procedure znode). During the initialization phase, the initialize methods are called by both
51  * {@link HMaster} and {@link HRegionServer} witch create the procedure znode and register the
52  * listeners. A procedure can be triggered by its signature and an instant name (encapsulated in
53  * a {@link ProcedureDescription} object). When the servers are shutdown, the stop methods on both
54  * classes are called to clean up the data associated with the procedure.
55  */
56  @InterfaceAudience.Private
57  @InterfaceStability.Evolving
58  public abstract class MasterProcedureManager extends ProcedureManager implements
59      Stoppable {
60    /**
61     * Initialize a globally barriered procedure for master.
62     *
63     * @param master Master service interface
64     * @throws KeeperException
65     * @throws IOException
66     * @throws UnsupportedOperationException
67     */
68    public abstract void initialize(MasterServices master, MetricsMaster metricsMaster)
69        throws KeeperException, IOException, UnsupportedOperationException;
70  
71    /**
72     * Execute a distributed procedure on cluster
73     *
74     * @param desc Procedure description
75     * @throws IOException
76     */
77    public void execProcedure(ProcedureDescription desc) throws IOException {
78  
79    }
80  
81    /**
82     * Execute a distributed procedure on cluster with return data.
83     *
84     * @param desc Procedure description
85     * @return data returned from the procedure execution, null if no data
86     * @throws IOException
87     */
88    public byte[] execProcedureWithRet(ProcedureDescription desc)
89        throws IOException {
90      return null;
91    }
92  
93    /**
94     * Check if the procedure is finished successfully
95     *
96     * @param desc Procedure description
97     * @return true if the specified procedure is finished successfully
98     * @throws IOException
99     */
100   public abstract boolean isProcedureDone(ProcedureDescription desc) throws IOException;
101 }