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  package org.apache.hadoop.hbase.master.cleaner;
19  
20  import java.io.IOException;
21  
22  import org.apache.commons.logging.Log;
23  import org.apache.commons.logging.LogFactory;
24  import org.apache.hadoop.classification.InterfaceAudience;
25  import org.apache.hadoop.conf.Configuration;
26  import org.apache.hadoop.fs.FileStatus;
27  import org.apache.hadoop.fs.FileSystem;
28  import org.apache.hadoop.fs.Path;
29  import org.apache.hadoop.hbase.io.HFileLink;
30  import org.apache.hadoop.hbase.util.FSUtils;
31  
32  /**
33   * HFileLink cleaner that determines if a hfile should be deleted.
34   * HFiles can be deleted only if there're no links to them.
35   *
36   * When a HFileLink is created a back reference file is created in:
37   *      /hbase/archive/table/region/cf/.links-hfile/ref-region.ref-table
38   * To check if the hfile can be deleted the back references folder must be empty.
39   */
40  @InterfaceAudience.Private
41  public class HFileLinkCleaner extends BaseHFileCleanerDelegate {
42    private static final Log LOG = LogFactory.getLog(HFileLinkCleaner.class);
43  
44    private FileSystem fs = null;
45  
46    @Override
47    public synchronized boolean isFileDeletable(FileStatus fStat) {
48      if (this.fs == null) return false;
49      Path filePath = fStat.getPath();
50      // HFile Link is always deletable
51      if (HFileLink.isHFileLink(filePath)) return true;
52  
53      // If the file is inside a link references directory, means that it is a back ref link.
54      // The back ref can be deleted only if the referenced file doesn't exists.
55      Path parentDir = filePath.getParent();
56      if (HFileLink.isBackReferencesDir(parentDir)) {
57        try {
58          Path hfilePath = HFileLink.getHFileFromBackReference(getConf(), filePath);
59          return !fs.exists(hfilePath);
60        } catch (IOException e) {
61          LOG.error("Couldn't verify if the referenced file still exists, keep it just in case");
62          return false;
63        }
64      }
65  
66      // HFile is deletable only if has no links
67      try {
68        Path backRefDir = HFileLink.getBackReferencesDir(parentDir, filePath.getName());
69        return FSUtils.listStatus(fs, backRefDir) == null;
70      } catch (IOException e) {
71        LOG.error("Couldn't get the references, not deleting file, just in case");
72        return false;
73      }
74    }
75  
76    @Override
77    public void setConf(Configuration conf) {
78      super.setConf(conf);
79  
80      // setup filesystem
81      try {
82        this.fs = FileSystem.get(this.getConf());
83      } catch (IOException e) {
84        LOG.error("Couldn't instantiate the file system, not deleting file, just in case");
85      }
86    }
87  }