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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  import java.util.LinkedList;
22  import java.util.List;
23  
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.logging.LogFactory;
26  import org.apache.hadoop.classification.InterfaceAudience;
27  import org.apache.hadoop.conf.Configuration;
28  import org.apache.hadoop.fs.FileSystem;
29  import org.apache.hadoop.fs.Path;
30  
31  import org.apache.hadoop.hbase.io.HFileLink;
32  import org.apache.hadoop.hbase.util.FSUtils;
33  import org.apache.hadoop.hbase.util.HFileArchiveUtil;
34  import org.apache.hadoop.hbase.master.cleaner.BaseHFileCleanerDelegate;
35  
36  /**
37   * HFileLink cleaner that determines if a hfile should be deleted.
38   * HFiles can be deleted only if there're no links to them.
39   *
40   * When a HFileLink is created a back reference file is created in:
41   *      /hbase/archive/table/region/cf/.links-hfile/ref-region.ref-table
42   * To check if the hfile can be deleted the back references folder must be empty.
43   */
44  @InterfaceAudience.Private
45  public class HFileLinkCleaner extends BaseHFileCleanerDelegate {
46    private static final Log LOG = LogFactory.getLog(HFileLinkCleaner.class);
47  
48    private FileSystem fs = null;
49  
50    @Override
51    public synchronized boolean isFileDeletable(Path filePath) {
52      if (this.fs == null) return false;
53  
54      // HFile Link is always deletable
55      if (HFileLink.isHFileLink(filePath)) return true;
56  
57      // If the file is inside a link references directory, means that it is a back ref link.
58      // The back ref can be deleted only if the referenced file doesn't exists.
59      Path parentDir = filePath.getParent();
60      if (HFileLink.isBackReferencesDir(parentDir)) {
61        try {
62          Path hfilePath = HFileLink.getHFileFromBackReference(getConf(), filePath);
63          return !fs.exists(hfilePath);
64        } catch (IOException e) {
65          LOG.error("Couldn't verify if the referenced file still exists, keep it just in case");
66          return false;
67        }
68      }
69  
70      // HFile is deletable only if has no links
71      try {
72        Path backRefDir = HFileLink.getBackReferencesDir(parentDir, filePath.getName());
73        return FSUtils.listStatus(fs, backRefDir) == null;
74      } catch (IOException e) {
75        LOG.error("Couldn't get the references, not deleting file, just in case");
76        return false;
77      }
78    }
79  
80    @Override
81    public void setConf(Configuration conf) {
82      super.setConf(conf);
83  
84      // setup filesystem
85      try {
86        this.fs = FileSystem.get(this.getConf());
87      } catch (IOException e) {
88        LOG.error("Couldn't instantiate the file system, not deleting file, just in case");
89      }
90    }
91  }