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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,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  
20  package org.apache.hadoop.hbase;
21  
22  import java.io.IOException;
23  
24  import org.apache.hadoop.hbase.classification.InterfaceAudience;
25  
26  /**
27   * Coprocessor interface.
28   */
29  @InterfaceAudience.Private
30  public interface Coprocessor {
31    int VERSION = 1;
32  
33    /** Highest installation priority */
34    int PRIORITY_HIGHEST = 0;
35    /** High (system) installation priority */
36    int PRIORITY_SYSTEM = Integer.MAX_VALUE / 4;
37    /** Default installation priority for user coprocessors */
38    int PRIORITY_USER = Integer.MAX_VALUE / 2;
39    /** Lowest installation priority */
40    int PRIORITY_LOWEST = Integer.MAX_VALUE;
41  
42    /**
43     * Lifecycle state of a given coprocessor instance.
44     */
45    enum State {
46      UNINSTALLED,
47      INSTALLED,
48      STARTING,
49      ACTIVE,
50      STOPPING,
51      STOPPED
52    }
53  
54    // Interface
55    void start(CoprocessorEnvironment env) throws IOException;
56  
57    void stop(CoprocessorEnvironment env) throws IOException;
58  
59  }