hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/KeyPrefixRegionSplitRestriction.java

   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 java.io.IOException;
  21 import java.util.Arrays;
  22 import org.apache.hadoop.conf.Configuration;
  23 import org.apache.hadoop.hbase.client.TableDescriptor;
  24 import org.apache.yetus.audience.InterfaceAudience;
  25 import org.slf4j.Logger;
  26 import org.slf4j.LoggerFactory;
  27
  28 /**
  29  * A {@link RegionSplitRestriction} implementation that groups rows by a prefix of the row-key.
  30  * <p>
  31  * This ensures that a region is not split "inside" a prefix of a row key.
  32  * I.e. rows can be co-located in a region by their prefix.
  33  */
  34 @InterfaceAudience.Private
  35 public class KeyPrefixRegionSplitRestriction extends RegionSplitRestriction {
  36   private static final Logger LOG =
  37     LoggerFactory.getLogger(KeyPrefixRegionSplitRestriction.class);
  38
  39   public static final String PREFIX_LENGTH_KEY =
  40     "hbase.regionserver.region.split_restriction.prefix_length";
  41
  42   private int prefixLength;
  43
  44   @Override
  45   public void initialize(TableDescriptor tableDescriptor, Configuration conf) throws IOException {
  46     String prefixLengthString = tableDescriptor.getValue(PREFIX_LENGTH_KEY);
  47     if (prefixLengthString == null) {
  48       prefixLengthString = conf.get(PREFIX_LENGTH_KEY);
  49       if (prefixLengthString == null) {
  50         LOG.error("{} not specified for table {}. "
  51           + "Using the default RegionSplitRestriction", PREFIX_LENGTH_KEY,
  52           tableDescriptor.getTableName());
  53         return;
  54       }
  55     }
  56     try {
  57       prefixLength = Integer.parseInt(prefixLengthString);
  58     } catch (NumberFormatException ignored) {
  59     }
  60     if (prefixLength <= 0) {
  61       LOG.error("Invalid value for {} for table {}:{}. "
  62         + "Using the default RegionSplitRestriction", PREFIX_LENGTH_KEY,
  63         tableDescriptor.getTableName(), prefixLengthString);
  64     }
  65   }
  66
  67   @Override
  68   public byte[] getRestrictedSplitPoint(byte[] splitPoint) {
  69     if (prefixLength > 0) {
  70       // group split keys by a prefix
  71       return Arrays.copyOf(splitPoint, Math.min(prefixLength, splitPoint.length));
  72     } else {
  73       return splitPoint;
  74     }
  75   }
  76 }