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1   /*
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.hadoop.hbase;
18  
19  import java.io.IOException;
20  
21  /**
22   * Coprocess interface.
23   */
24  public interface Coprocessor {
25    static final int VERSION = 1;
26  
27    /** Highest installation priority */
28    static final int PRIORITY_HIGHEST = 0;
29    /** High (system) installation priority */
30    static final int PRIORITY_SYSTEM = Integer.MAX_VALUE / 4;
31    /** Default installation priority for user coprocessors */
32    static final int PRIORITY_USER = Integer.MAX_VALUE / 2;
33    /** Lowest installation priority */
34    static final int PRIORITY_LOWEST = Integer.MAX_VALUE;
35  
36    /**
37     * Lifecycle state of a given coprocessor instance.
38     */
39    public enum State {
40      UNINSTALLED,
41      INSTALLED,
42      STARTING,
43      ACTIVE,
44      STOPPING,
45      STOPPED
46    }
47  
48    // Interface
49    void start(CoprocessorEnvironment env) throws IOException;
50  
51    void stop(CoprocessorEnvironment env) throws IOException;
52  }