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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.FileStatus;
29  import org.apache.hadoop.fs.FileSystem;
30  import org.apache.hadoop.fs.Path;
31  
32  import org.apache.hadoop.hbase.io.HFileLink;
33  import org.apache.hadoop.hbase.util.FSUtils;
34  import org.apache.hadoop.hbase.util.HFileArchiveUtil;
35  import org.apache.hadoop.hbase.master.cleaner.BaseHFileCleanerDelegate;
36  
37  /**
38   * HFileLink cleaner that determines if a hfile should be deleted.
39   * HFiles can be deleted only if there're no links to them.
40   *
41   * When a HFileLink is created a back reference file is created in:
42   *      /hbase/archive/table/region/cf/.links-hfile/ref-region.ref-table
43   * To check if the hfile can be deleted the back references folder must be empty.
44   */
45  @InterfaceAudience.Private
46  public class HFileLinkCleaner extends BaseHFileCleanerDelegate {
47    private static final Log LOG = LogFactory.getLog(HFileLinkCleaner.class);
48  
49    private FileSystem fs = null;
50  
51    @Override
52    public synchronized boolean isFileDeletable(FileStatus fStat) {
53      if (this.fs == null) return false;
54      Path filePath = fStat.getPath();
55      // HFile Link is always deletable
56      if (HFileLink.isHFileLink(filePath)) return true;
57  
58      // If the file is inside a link references directory, means that it is a back ref link.
59      // The back ref can be deleted only if the referenced file doesn't exists.
60      Path parentDir = filePath.getParent();
61      if (HFileLink.isBackReferencesDir(parentDir)) {
62        try {
63          Path hfilePath = HFileLink.getHFileFromBackReference(getConf(), filePath);
64          return !fs.exists(hfilePath);
65        } catch (IOException e) {
66          LOG.error("Couldn't verify if the referenced file still exists, keep it just in case");
67          return false;
68        }
69      }
70  
71      // HFile is deletable only if has no links
72      try {
73        Path backRefDir = HFileLink.getBackReferencesDir(parentDir, filePath.getName());
74        return FSUtils.listStatus(fs, backRefDir) == null;
75      } catch (IOException e) {
76        LOG.error("Couldn't get the references, not deleting file, just in case");
77        return false;
78      }
79    }
80  
81    @Override
82    public void setConf(Configuration conf) {
83      super.setConf(conf);
84  
85      // setup filesystem
86      try {
87        this.fs = FileSystem.get(this.getConf());
88      } catch (IOException e) {
89        LOG.error("Couldn't instantiate the file system, not deleting file, just in case");
90      }
91    }
92  }