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1   /*
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.replication.master;
21  
22  import org.apache.commons.logging.Log;
23  import org.apache.commons.logging.LogFactory;
24  import org.apache.hadoop.conf.Configuration;
25  import org.apache.hadoop.fs.Path;
26  import org.apache.hadoop.hbase.Abortable;
27  import org.apache.hadoop.hbase.HConstants;
28  import org.apache.hadoop.hbase.client.HConnectionManager;
29  import org.apache.hadoop.hbase.master.LogCleanerDelegate;
30  import org.apache.hadoop.hbase.replication.ReplicationZookeeper;
31  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
32  import org.apache.zookeeper.KeeperException;
33  
34  import java.io.IOException;
35  import java.util.HashSet;
36  import java.util.List;
37  import java.util.Set;
38  
39  /**
40   * Implementation of a log cleaner that checks if a log is still scheduled for
41   * replication before deleting it when its TTL is over.
42   */
43  public class ReplicationLogCleaner implements LogCleanerDelegate, Abortable {
44    private static final Log LOG = LogFactory.getLog(ReplicationLogCleaner.class);
45    private Configuration conf;
46    private ReplicationZookeeper zkHelper;
47    private Set<String> hlogs = new HashSet<String>();
48    private boolean stopped = false;
49    private boolean aborted;
50  
51    /**
52     * Instantiates the cleaner, does nothing more.
53     */
54    public ReplicationLogCleaner() {}
55  
56    @Override
57    public boolean isLogDeletable(Path filePath) {
58  
59      try {
60        if (!zkHelper.getReplication()) {
61          return false;
62        }
63      } catch (KeeperException e) {
64        abort("Cannot get the state of replication", e);
65        return false;
66      }
67  
68      // all members of this class are null if replication is disabled, and we
69      // return true since false would render the LogsCleaner useless
70      if (this.conf == null) {
71        return true;
72      }
73      String log = filePath.getName();
74      // If we saw the hlog previously, let's consider it's still used
75      // At some point in the future we will refresh the list and it will be gone
76      if (this.hlogs.contains(log)) {
77        return false;
78      }
79  
80      // Let's see it's still there
81      // This solution makes every miss very expensive to process since we
82      // almost completely refresh the cache each time
83      return !refreshHLogsAndSearch(log);
84    }
85  
86    /**
87     * Search through all the hlogs we have in ZK to refresh the cache
88     * If a log is specified and found, then we early out and return true
89     * @param searchedLog log we are searching for, pass null to cache everything
90     *                    that's in zookeeper.
91     * @return false until a specified log is found.
92     */
93    private boolean refreshHLogsAndSearch(String searchedLog) {
94      this.hlogs.clear();
95      final boolean lookForLog = searchedLog != null;
96      List<String> rss = zkHelper.getListOfReplicators();
97      if (rss == null) {
98        LOG.debug("Didn't find any region server that replicates, deleting: " +
99            searchedLog);
100       return false;
101     }
102     for (String rs: rss) {
103       List<String> listOfPeers = zkHelper.getListPeersForRS(rs);
104       // if rs just died, this will be null
105       if (listOfPeers == null) {
106         continue;
107       }
108       for (String id : listOfPeers) {
109         List<String> peersHlogs = zkHelper.getListHLogsForPeerForRS(rs, id);
110         if (peersHlogs != null) {
111           this.hlogs.addAll(peersHlogs);
112         }
113         // early exit if we found the log
114         if(lookForLog && this.hlogs.contains(searchedLog)) {
115           LOG.debug("Found log in ZK, keeping: " + searchedLog);
116           return true;
117         }
118       }
119     }
120     LOG.debug("Didn't find this log in ZK, deleting: " + searchedLog);
121     return false;
122   }
123 
124   @Override
125   public void setConf(Configuration conf) {
126     // If replication is disabled, keep all members null
127     if (!conf.getBoolean(HConstants.REPLICATION_ENABLE_KEY, false)) {
128       return;
129     }
130     // Make my own Configuration.  Then I'll have my own connection to zk that
131     // I can close myself when comes time.
132     this.conf = new Configuration(conf);
133     try {
134       ZooKeeperWatcher zkw =
135           new ZooKeeperWatcher(this.conf, "replicationLogCleaner", null);
136       this.zkHelper = new ReplicationZookeeper(this, this.conf, zkw);
137     } catch (KeeperException e) {
138       LOG.error("Error while configuring " + this.getClass().getName(), e);
139     } catch (IOException e) {
140       LOG.error("Error while configuring " + this.getClass().getName(), e);
141     }
142     refreshHLogsAndSearch(null);
143   }
144 
145   @Override
146   public Configuration getConf() {
147     return conf;
148   }
149 
150   @Override
151   public void stop(String why) {
152     if (this.stopped) return;
153     this.stopped = true;
154     if (this.zkHelper != null) {
155       LOG.info("Stopping " + this.zkHelper.getZookeeperWatcher());
156       this.zkHelper.getZookeeperWatcher().close();
157     }
158     // Not sure why we're deleting a connection that we never acquired or used
159     HConnectionManager.deleteConnection(this.conf, true);
160   }
161 
162   @Override
163   public boolean isStopped() {
164     return this.stopped;
165   }
166 
167   @Override
168   public void abort(String why, Throwable e) {
169     LOG.warn("Aborting ReplicationLogCleaner because " + why, e);
170     this.aborted = true;
171     stop(why);
172   }
173 
174   @Override
175   public boolean isAborted() {
176     return this.aborted;
177   }
178 }