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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 org.apache.commons.logging.Log;
22  import org.apache.commons.logging.LogFactory;
23  import org.apache.hadoop.conf.Configuration;
24  import org.apache.hadoop.fs.FileStatus;
25  import org.apache.hadoop.fs.FileSystem;
26  import org.apache.hadoop.fs.Path;
27  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
28  import org.apache.hadoop.hbase.HConstants;
29  import org.apache.hadoop.hbase.classification.InterfaceAudience;
30  import org.apache.hadoop.hbase.io.HFileLink;
31  import org.apache.hadoop.hbase.mob.MobUtils;
32  import org.apache.hadoop.hbase.util.FSUtils;
33  
34  /**
35   * HFileLink cleaner that determines if a hfile should be deleted.
36   * HFiles can be deleted only if there're no links to them.
37   *
38   * When a HFileLink is created a back reference file is created in:
39   *      /hbase/archive/table/region/cf/.links-hfile/ref-region.ref-table
40   * To check if the hfile can be deleted the back references folder must be empty.
41   */
42  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
43  public class HFileLinkCleaner extends BaseHFileCleanerDelegate {
44    private static final Log LOG = LogFactory.getLog(HFileLinkCleaner.class);
45  
46    private FileSystem fs = null;
47  
48    @Override
49    public synchronized boolean isFileDeletable(FileStatus fStat) {
50      if (this.fs == null) return false;
51      Path filePath = fStat.getPath();
52      // HFile Link is always deletable
53      if (HFileLink.isHFileLink(filePath)) return true;
54  
55      // If the file is inside a link references directory, means that it is a back ref link.
56      // The back ref can be deleted only if the referenced file doesn't exists.
57      Path parentDir = filePath.getParent();
58      if (HFileLink.isBackReferencesDir(parentDir)) {
59        Path hfilePath = null;
60        try {
61          // Also check if the HFile is in the HBASE_TEMP_DIRECTORY; this is where the referenced
62          // file gets created when cloning a snapshot.
63          hfilePath = HFileLink.getHFileFromBackReference(
64              new Path(FSUtils.getRootDir(getConf()), HConstants.HBASE_TEMP_DIRECTORY), filePath);
65          if (fs.exists(hfilePath)) {
66            return false;
67          }
68          // check whether the HFileLink still exists in mob dir.
69          hfilePath = HFileLink.getHFileFromBackReference(MobUtils.getMobHome(getConf()), filePath);
70          if (fs.exists(hfilePath)) {
71            return false;
72          }
73          hfilePath = HFileLink.getHFileFromBackReference(FSUtils.getRootDir(getConf()), filePath);
74          return !fs.exists(hfilePath);
75        } catch (IOException e) {
76          if (LOG.isDebugEnabled()) {
77            LOG.debug("Couldn't verify if the referenced file still exists, keep it just in case: "
78                + hfilePath);
79          }
80          return false;
81        }
82      }
83  
84      // HFile is deletable only if has no links
85      Path backRefDir = null;
86      try {
87        backRefDir = HFileLink.getBackReferencesDir(parentDir, filePath.getName());
88        return FSUtils.listStatus(fs, backRefDir) == null;
89      } catch (IOException e) {
90        if (LOG.isDebugEnabled()) {
91          LOG.debug("Couldn't get the references, not deleting file, just in case. filePath="
92              + filePath + ", backRefDir=" + backRefDir);
93        }
94        return false;
95      }
96    }
97  
98    @Override
99    public void setConf(Configuration conf) {
100     super.setConf(conf);
101 
102     // setup filesystem
103     try {
104       this.fs = FileSystem.get(this.getConf());
105     } catch (IOException e) {
106       if (LOG.isDebugEnabled()) {
107         LOG.debug("Couldn't instantiate the file system, not deleting file, just in case. "
108             + FileSystem.FS_DEFAULT_NAME_KEY + "="
109             + getConf().get(FileSystem.FS_DEFAULT_NAME_KEY, FileSystem.DEFAULT_FS));
110       }
111     }
112   }
113 }