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 package org.apache.hadoop.hdfs;
19 
20 import static org.junit.Assert.assertEquals;
21 
22 import java.io.IOException;
23 import java.util.ArrayList;
24 
25 import org.apache.hadoop.fs.FSDataOutputStream;
26 import org.apache.hadoop.fs.FileSystem;
27 import org.apache.hadoop.fs.Path;
28 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
29 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeManager;
30 import org.junit.After;
31 import org.junit.Test;
32 
33 /**
34  * This class tests DatanodeDescriptor.getBlocksScheduled() at the
35  * NameNode. This counter is supposed to keep track of blocks currently
36  * scheduled to a datanode.
37  */
38 public class TestBlocksScheduledCounter {
39   MiniDFSCluster cluster = null;
40   FileSystem fs = null;
41 
42   @After
tearDown()43   public void tearDown() throws IOException {
44     if (fs != null) {
45       fs.close();
46     }
47     if(cluster!=null){
48       cluster.shutdown();
49     }
50   }
51 
52   @Test
testBlocksScheduledCounter()53   public void testBlocksScheduledCounter() throws IOException {
54     cluster = new MiniDFSCluster.Builder(new HdfsConfiguration()).build();
55 
56     cluster.waitActive();
57     fs = cluster.getFileSystem();
58 
59     //open a file an write a few bytes:
60     FSDataOutputStream out = fs.create(new Path("/testBlockScheduledCounter"));
61     for (int i=0; i<1024; i++) {
62       out.write(i);
63     }
64     // flush to make sure a block is allocated.
65     out.hflush();
66 
67     ArrayList<DatanodeDescriptor> dnList = new ArrayList<DatanodeDescriptor>();
68     final DatanodeManager dm = cluster.getNamesystem().getBlockManager(
69         ).getDatanodeManager();
70     dm.fetchDatanodes(dnList, dnList, false);
71     DatanodeDescriptor dn = dnList.get(0);
72 
73     assertEquals(1, dn.getBlocksScheduled());
74 
75     // close the file and the counter should go to zero.
76     out.close();
77     assertEquals(0, dn.getBlocksScheduled());
78   }
79 }
80