View Javadoc

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.coprocessor;
18  
19  import java.io.IOException;
20  
21  import org.apache.hadoop.hbase.Coprocessor;
22  import org.apache.hadoop.hbase.CoprocessorEnvironment;
23  import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;
24  import org.apache.hadoop.hbase.ipc.ProtocolSignature;
25  import org.apache.hadoop.hbase.ipc.VersionedProtocol;
26  
27  /**
28   * This abstract class provides default implementation of an Endpoint.
29   * It also maintains a CoprocessorEnvironment object which can be
30   * used to access region resource.
31   *
32   * It's recommended to use this abstract class to implement your Endpoint.
33   * However you still can just implement the interface CoprocessorProtocol
34   * and Coprocessor to develop an Endpoint. But you won't be able to access
35   * the region related resource, i.e., CoprocessorEnvironment.
36   */
37  public abstract class BaseEndpointCoprocessor implements Coprocessor,
38      CoprocessorProtocol, VersionedProtocol {
39    /**
40     * This Interfaces' version. Version changes when the Interface changes.
41     */
42    // All HBase Interfaces used derive from HBaseRPCProtocolVersion.  It
43    // maintained a single global version number on all HBase Interfaces.  This
44    // meant all HBase RPC was broke though only one of the three RPC Interfaces
45    // had changed.  This has since been undone.
46    public static final long VERSION = 28L;
47  
48    private CoprocessorEnvironment env;
49  
50    /**
51     * @return env Coprocessor environment.
52     */
53    public CoprocessorEnvironment getEnvironment() {
54      return env;
55    }
56  
57    @Override
58    public void start(CoprocessorEnvironment env) {
59      this.env = env;
60    }
61  
62    @Override
63    public void stop(CoprocessorEnvironment env) { }
64  
65    @Override
66    public ProtocolSignature getProtocolSignature(
67        String protocol, long version, int clientMethodsHashCode)
68    throws IOException {
69      return new ProtocolSignature(VERSION, null);
70    }
71  
72    @Override
73    public long getProtocolVersion(String protocol, long clientVersion)
74    throws IOException {
75      return VERSION;
76    }
77  }