View Javadoc

1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  package org.apache.hadoop.hbase.master.handler;
20  
21  import java.io.FileNotFoundException;
22  import java.io.IOException;
23  import java.util.ArrayList;
24  import java.util.LinkedList;
25  import java.util.List;
26  import java.util.NavigableMap;
27  import java.util.TreeMap;
28  
29  import org.apache.commons.logging.Log;
30  import org.apache.commons.logging.LogFactory;
31  import org.apache.hadoop.classification.InterfaceAudience;
32  import org.apache.hadoop.hbase.TableName;
33  import org.apache.hadoop.hbase.HRegionInfo;
34  import org.apache.hadoop.hbase.HTableDescriptor;
35  import org.apache.hadoop.hbase.InvalidFamilyOperationException;
36  import org.apache.hadoop.hbase.Server;
37  import org.apache.hadoop.hbase.ServerName;
38  import org.apache.hadoop.hbase.TableExistsException;
39  import org.apache.hadoop.hbase.TableNotDisabledException;
40  import org.apache.hadoop.hbase.catalog.MetaReader;
41  import org.apache.hadoop.hbase.client.HTable;
42  import org.apache.hadoop.hbase.executor.EventHandler;
43  import org.apache.hadoop.hbase.executor.EventType;
44  import org.apache.hadoop.hbase.master.BulkReOpen;
45  import org.apache.hadoop.hbase.master.MasterServices;
46  import org.apache.hadoop.hbase.master.TableLockManager.TableLock;
47  import org.apache.hadoop.hbase.util.Bytes;
48  import org.apache.zookeeper.KeeperException;
49  
50  import com.google.common.collect.Lists;
51  import com.google.common.collect.Maps;
52  
53  /**
54   * Base class for performing operations against tables.
55   * Checks on whether the process can go forward are done in constructor rather
56   * than later on in {@link #process()}.  The idea is to fail fast rather than
57   * later down in an async invocation of {@link #process()} (which currently has
58   * no means of reporting back issues once started).
59   */
60  @InterfaceAudience.Private
61  public abstract class TableEventHandler extends EventHandler {
62    private static final Log LOG = LogFactory.getLog(TableEventHandler.class);
63    protected final MasterServices masterServices;
64    protected final TableName tableName;
65    protected TableLock tableLock;
66    private boolean isPrepareCalled = false;
67  
68    public TableEventHandler(EventType eventType, TableName tableName, Server server,
69        MasterServices masterServices) {
70      super(server, eventType);
71      this.masterServices = masterServices;
72      this.tableName = tableName;
73    }
74  
75    public TableEventHandler prepare() throws IOException {
76      //acquire the table write lock, blocking
77      this.tableLock = masterServices.getTableLockManager()
78          .writeLock(tableName, eventType.toString());
79      this.tableLock.acquire();
80      boolean success = false;
81      try {
82        try {
83          this.masterServices.checkTableModifiable(tableName);
84        } catch (TableNotDisabledException ex)  {
85          if (isOnlineSchemaChangeAllowed()
86              && eventType.isOnlineSchemaChangeSupported()) {
87            LOG.debug("Ignoring table not disabled exception " +
88                "for supporting online schema changes.");
89          } else {
90            throw ex;
91          }
92        }
93        prepareWithTableLock();
94        success = true;
95      } finally {
96        if (!success ) {
97          releaseTableLock();
98        }
99      }
100     this.isPrepareCalled = true;
101     return this;
102   }
103 
104   /** Called from prepare() while holding the table lock. Subclasses
105    * can do extra initialization, and not worry about the releasing
106    * the table lock. */
107   protected void prepareWithTableLock() throws IOException {
108   }
109 
110   private boolean isOnlineSchemaChangeAllowed() {
111     return this.server.getConfiguration().getBoolean(
112       "hbase.online.schema.update.enable", false);
113   }
114 
115   @Override
116   public void process() {
117     if (!isPrepareCalled) {
118       //For proper table locking semantics, the implementor should ensure to call
119       //TableEventHandler.prepare() before calling process()
120       throw new RuntimeException("Implementation should have called prepare() first");
121     }
122     try {
123       LOG.info("Handling table operation " + eventType + " on table " +
124           tableName);
125 
126       List<HRegionInfo> hris =
127         MetaReader.getTableRegions(this.server.getCatalogTracker(),
128           tableName);
129       handleTableOperation(hris);
130       if (eventType.isOnlineSchemaChangeSupported() && this.masterServices.
131           getAssignmentManager().getZKTable().
132           isEnabledTable(tableName)) {
133         if (reOpenAllRegions(hris)) {
134           LOG.info("Completed table operation " + eventType + " on table " +
135               tableName);
136         } else {
137           LOG.warn("Error on reopening the regions");
138         }
139       }
140       completed(null);
141     } catch (IOException e) {
142       LOG.error("Error manipulating table " + tableName, e);
143       completed(e);
144     } catch (KeeperException e) {
145       LOG.error("Error manipulating table " + tableName, e);
146       completed(e);
147     } finally {
148       releaseTableLock();
149     }
150   }
151 
152   protected void releaseTableLock() {
153     if (this.tableLock != null) {
154       try {
155         this.tableLock.release();
156       } catch (IOException ex) {
157         LOG.warn("Could not release the table lock", ex);
158       }
159     }
160   }
161 
162   /**
163    * Called after that process() is completed.
164    * @param exception null if process() is successful or not null if something has failed.
165    */
166   protected void completed(final Throwable exception) {
167   }
168 
169   public boolean reOpenAllRegions(List<HRegionInfo> regions) throws IOException {
170     boolean done = false;
171     LOG.info("Bucketing regions by region server...");
172     HTable table = new HTable(masterServices.getConfiguration(), tableName);
173     TreeMap<ServerName, List<HRegionInfo>> serverToRegions = Maps
174         .newTreeMap();
175     NavigableMap<HRegionInfo, ServerName> hriHserverMapping;
176     try {
177       hriHserverMapping = table.getRegionLocations();
178     } finally {
179       table.close();
180     }
181 
182     List<HRegionInfo> reRegions = new ArrayList<HRegionInfo>();
183     for (HRegionInfo hri : regions) {
184       ServerName rsLocation = hriHserverMapping.get(hri);
185 
186       // Skip the offlined split parent region
187       // See HBASE-4578 for more information.
188       if (null == rsLocation) {
189         LOG.info("Skip " + hri);
190         continue;
191       }
192       if (!serverToRegions.containsKey(rsLocation)) {
193         LinkedList<HRegionInfo> hriList = Lists.newLinkedList();
194         serverToRegions.put(rsLocation, hriList);
195       }
196       reRegions.add(hri);
197       serverToRegions.get(rsLocation).add(hri);
198     }
199 
200     LOG.info("Reopening " + reRegions.size() + " regions on "
201         + serverToRegions.size() + " region servers.");
202     this.masterServices.getAssignmentManager().setRegionsToReopen(reRegions);
203     BulkReOpen bulkReopen = new BulkReOpen(this.server, serverToRegions,
204         this.masterServices.getAssignmentManager());
205     while (true) {
206       try {
207         if (bulkReopen.bulkReOpen()) {
208           done = true;
209           break;
210         } else {
211           LOG.warn("Timeout before reopening all regions");
212         }
213       } catch (InterruptedException e) {
214         LOG.warn("Reopen was interrupted");
215         // Preserve the interrupt.
216         Thread.currentThread().interrupt();
217         break;
218       }
219     }
220     return done;
221   }
222 
223 
224   /**
225    * Gets a TableDescriptor from the masterServices.  Can Throw exceptions.
226    *
227    * @return Table descriptor for this table
228    * @throws TableExistsException
229    * @throws FileNotFoundException
230    * @throws IOException
231    */
232   public HTableDescriptor getTableDescriptor()
233   throws FileNotFoundException, IOException {
234     HTableDescriptor htd =
235       this.masterServices.getTableDescriptors().get(tableName);
236     if (htd == null) {
237       throw new IOException("HTableDescriptor missing for " + tableName);
238     }
239     return htd;
240   }
241 
242   byte [] hasColumnFamily(final HTableDescriptor htd, final byte [] cf)
243   throws InvalidFamilyOperationException {
244     if (!htd.hasFamily(cf)) {
245       throw new InvalidFamilyOperationException("Column family '" +
246         Bytes.toString(cf) + "' does not exist");
247     }
248     return cf;
249   }
250 
251   protected abstract void handleTableOperation(List<HRegionInfo> regions)
252   throws IOException, KeeperException;
253 }