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1   /*
2    *
3    * Licensed under the Apache License, Version 2.0 (the "License");
4    * you may not use this file except in compliance with the License.
5    * You may obtain a copy of the License at
6    *
7    *     http://www.apache.org/licenses/LICENSE-2.0
8    *
9    * Unless required by applicable law or agreed to in writing, software
10   * distributed under the License is distributed on an "AS IS" BASIS,
11   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12   * See the License for the specific language governing permissions and
13   * limitations under the License.
14   */
15  
16  package org.apache.hadoop.hbase;
17  
18  import java.io.IOException;
19  
20  import org.apache.hadoop.classification.InterfaceAudience;
21  
22  /**
23   * Coprocessor interface.
24   */
25  @InterfaceAudience.Private
26  public interface Coprocessor {
27    int VERSION = 1;
28  
29    /** Highest installation priority */
30    int PRIORITY_HIGHEST = 0;
31    /** High (system) installation priority */
32    int PRIORITY_SYSTEM = Integer.MAX_VALUE / 4;
33    /** Default installation priority for user coprocessors */
34    int PRIORITY_USER = Integer.MAX_VALUE / 2;
35    /** Lowest installation priority */
36    int PRIORITY_LOWEST = Integer.MAX_VALUE;
37  
38    /**
39     * Lifecycle state of a given coprocessor instance.
40     */
41    enum State {
42      UNINSTALLED,
43      INSTALLED,
44      STARTING,
45      ACTIVE,
46      STOPPING,
47      STOPPED
48    }
49  
50    // Interface
51    void start(CoprocessorEnvironment env) throws IOException;
52  
53    void stop(CoprocessorEnvironment env) throws IOException;
54  
55  }