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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.regionserver;
19  
20  import org.apache.hadoop.hbase.classification.InterfaceAudience;
21  import org.apache.hadoop.conf.Configuration;
22  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
23  import org.apache.hadoop.hbase.HConstants;
24  import org.apache.hadoop.hbase.HTableDescriptor;
25  
26  import java.util.Random;
27  
28  /**
29   * A {@link RegionSplitPolicy} implementation which splits a region
30   * as soon as any of its store files exceeds a maximum configurable
31   * size.
32   * <p>
33   * This is the default split policy. From 0.94.0 on the default split policy has
34   * changed to {@link IncreasingToUpperBoundRegionSplitPolicy}
35   * </p>
36   */
37  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
38  public class ConstantSizeRegionSplitPolicy extends RegionSplitPolicy {
39    private static final Random RANDOM = new Random();
40  
41    private long desiredMaxFileSize;
42  
43    @Override
44    protected void configureForRegion(HRegion region) {
45      super.configureForRegion(region);
46      Configuration conf = getConf();
47      HTableDescriptor desc = region.getTableDesc();
48      if (desc != null) {
49        this.desiredMaxFileSize = desc.getMaxFileSize();
50      }
51      if (this.desiredMaxFileSize <= 0) {
52        this.desiredMaxFileSize = conf.getLong(HConstants.HREGION_MAX_FILESIZE,
53          HConstants.DEFAULT_MAX_FILE_SIZE);
54      }
55      double jitter = conf.getDouble("hbase.hregion.max.filesize.jitter", 0.25D);
56      this.desiredMaxFileSize += (long)(desiredMaxFileSize * (RANDOM.nextFloat() - 0.5D) * jitter);
57    }
58  
59    @Override
60    protected boolean shouldSplit() {
61      boolean force = region.shouldForceSplit();
62      boolean foundABigStore = false;
63  
64      for (Store store : region.getStores()) {
65        // If any of the stores are unable to split (eg they contain reference files)
66        // then don't split
67        if ((!store.canSplit())) {
68          return false;
69        }
70  
71        // Mark if any store is big enough
72        if (store.getSize() > desiredMaxFileSize) {
73          foundABigStore = true;
74        }
75      }
76  
77      return foundABigStore || force;
78    }
79  
80    long getDesiredMaxFileSize() {
81      return desiredMaxFileSize;
82    }
83  }