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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.regionserver;
20  
21  import java.io.IOException;
22  
23  import org.apache.commons.logging.Log;
24  import org.apache.commons.logging.LogFactory;
25  import org.apache.hadoop.hbase.classification.InterfaceAudience;
26  import org.apache.hadoop.hbase.master.TableLockManager.TableLock;
27  import org.apache.hadoop.hbase.util.Bytes;
28  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
29  import org.apache.hadoop.ipc.RemoteException;
30  import org.apache.hadoop.util.StringUtils;
31  
32  import com.google.common.base.Preconditions;
33  
34  /**
35   * Handles processing region splits. Put in a queue, owned by HRegionServer.
36   */
37  @InterfaceAudience.Private
38  class SplitRequest implements Runnable {
39    static final Log LOG = LogFactory.getLog(SplitRequest.class);
40    private final HRegion parent;
41    private final byte[] midKey;
42    private final HRegionServer server;
43    private TableLock tableLock;
44  
45    SplitRequest(HRegion region, byte[] midKey, HRegionServer hrs) {
46      Preconditions.checkNotNull(hrs);
47      this.parent = region;
48      this.midKey = midKey;
49      this.server = hrs;
50    }
51  
52    @Override
53    public String toString() {
54      return "regionName=" + parent + ", midKey=" + Bytes.toStringBinary(midKey);
55    }
56  
57    @Override
58    public void run() {
59      if (this.server.isStopping() || this.server.isStopped()) {
60        LOG.debug("Skipping split because server is stopping=" +
61          this.server.isStopping() + " or stopped=" + this.server.isStopped());
62        return;
63      }
64      boolean success = false;
65      server.metricsRegionServer.incrSplitRequest();
66      long startTime = EnvironmentEdgeManager.currentTime();
67      SplitTransaction st = new SplitTransaction(parent, midKey);
68      try {
69        //acquire a shared read lock on the table, so that table schema modifications
70        //do not happen concurrently
71        tableLock = server.getTableLockManager().readLock(parent.getTableDesc().getTableName()
72            , "SPLIT_REGION:" + parent.getRegionNameAsString());
73        try {
74          tableLock.acquire();
75        } catch (IOException ex) {
76          tableLock = null;
77          throw ex;
78        }
79  
80        // If prepare does not return true, for some reason -- logged inside in
81        // the prepare call -- we are not ready to split just now. Just return.
82        if (!st.prepare()) return;
83        try {
84          st.execute(this.server, this.server);
85          success = true;
86        } catch (Exception e) {
87          if (this.server.isStopping() || this.server.isStopped()) {
88            LOG.info(
89                "Skip rollback/cleanup of failed split of "
90                    + parent.getRegionNameAsString() + " because server is"
91                    + (this.server.isStopping() ? " stopping" : " stopped"), e);
92            return;
93          }
94          try {
95            LOG.info("Running rollback/cleanup of failed split of " +
96              parent.getRegionNameAsString() + "; " + e.getMessage(), e);
97            if (st.rollback(this.server, this.server)) {
98              LOG.info("Successful rollback of failed split of " +
99                parent.getRegionNameAsString());
100           } else {
101             this.server.abort("Abort; we got an error after point-of-no-return");
102           }
103         } catch (RuntimeException ee) {
104           String msg = "Failed rollback of failed split of " +
105             parent.getRegionNameAsString() + " -- aborting server";
106           // If failed rollback, kill this server to avoid having a hole in table.
107           LOG.info(msg, ee);
108           this.server.abort(msg + " -- Cause: " + ee.getMessage());
109         }
110         return;
111       }
112     } catch (IOException ex) {
113       ex = ex instanceof RemoteException ? ((RemoteException) ex).unwrapRemoteException() : ex;
114       LOG.error("Split failed " + this, ex);
115       server.checkFileSystem();
116     } finally {
117       if (this.parent.getCoprocessorHost() != null) {
118         try {
119           this.parent.getCoprocessorHost().postCompleteSplit();
120         } catch (IOException io) {
121           LOG.error("Split failed " + this,
122             io instanceof RemoteException ? ((RemoteException) io).unwrapRemoteException() : io);
123         }
124       }
125       if (parent.shouldForceSplit()) {
126         parent.clearSplit();
127       }
128       releaseTableLock();
129       long endTime = EnvironmentEdgeManager.currentTime();
130       // Update regionserver metrics with the split transaction total running time
131       server.metricsRegionServer.updateSplitTime(endTime - startTime);
132       if (success) {
133         server.metricsRegionServer.incrSplitSuccess();
134         // Log success
135         LOG.info("Region split, hbase:meta updated, and report to master. Parent="
136             + parent.getRegionNameAsString() + ", new regions: "
137             + st.getFirstDaughter().getRegionNameAsString() + ", "
138             + st.getSecondDaughter().getRegionNameAsString() + ". Split took "
139             + StringUtils.formatTimeDiff(EnvironmentEdgeManager.currentTime(), startTime));
140       }
141       // Always log the split transaction journal
142       LOG.info("Split transaction journal:\n\t" + StringUtils.join("\n\t", st.getJournal()));
143     }
144   }
145 
146   protected void releaseTableLock() {
147     if (this.tableLock != null) {
148       try {
149         this.tableLock.release();
150       } catch (IOException ex) {
151         LOG.error("Could not release the table lock (something is really wrong). " 
152            + "Aborting this server to avoid holding the lock forever.");
153         this.server.abort("Abort; we got an error when releasing the table lock "
154                          + "on " + parent.getRegionNameAsString());
155       }
156     }
157   }
158 }