View Javadoc

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  
19  package org.apache.hadoop.hbase;
20  
21  import java.io.IOException;
22  
23  
24  /**
25   * A compatibility shim layer for interacting with different versions of Hadoop.
26   */
27  //NOTE: we can move this under src/main if main code wants to use this shim layer
28  public interface HadoopShims {
29  
30    /**
31     * Returns a TaskAttemptContext instance created from the given parameters.
32     * @param job an instance of o.a.h.mapreduce.Job
33     * @param taskId an identifier for the task attempt id. Should be parsable by
34     * TaskAttemptId.forName()
35     * @return a concrete TaskAttemptContext instance of o.a.h.mapreduce.TaskAttemptContext
36     */
37    <T,J> T createTestTaskAttemptContext(final J job, final String taskId);
38  
39    /**
40     * Returns an array of DatanodeInfo for all live datanodes in the cluster
41     * @param dfs instance of DistributedFileSystem
42     * @return
43     */
44    <I,DFS> I[] getLiveDatanodes(DFS dfs) throws IOException;
45  }