001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.regionserver;
019
020import java.io.IOException;
021import java.util.Arrays;
022import org.apache.hadoop.conf.Configuration;
023import org.apache.hadoop.hbase.client.TableDescriptor;
024import org.apache.yetus.audience.InterfaceAudience;
025import org.slf4j.Logger;
026import org.slf4j.LoggerFactory;
027
028/**
029 * A {@link RegionSplitRestriction} implementation that groups rows by a prefix of the row-key.
030 * <p>
031 * This ensures that a region is not split "inside" a prefix of a row key. I.e. rows can be
032 * co-located in a region by their prefix.
033 */
034@InterfaceAudience.Private
035public class KeyPrefixRegionSplitRestriction extends RegionSplitRestriction {
036  private static final Logger LOG = LoggerFactory.getLogger(KeyPrefixRegionSplitRestriction.class);
037
038  public static final String PREFIX_LENGTH_KEY =
039    "hbase.regionserver.region.split_restriction.prefix_length";
040
041  private int prefixLength;
042
043  @Override
044  public void initialize(TableDescriptor tableDescriptor, Configuration conf) throws IOException {
045    String prefixLengthString = tableDescriptor.getValue(PREFIX_LENGTH_KEY);
046    if (prefixLengthString == null) {
047      prefixLengthString = conf.get(PREFIX_LENGTH_KEY);
048      if (prefixLengthString == null) {
049        LOG.error("{} not specified for table {}. " + "Using the default RegionSplitRestriction",
050          PREFIX_LENGTH_KEY, tableDescriptor.getTableName());
051        return;
052      }
053    }
054    try {
055      prefixLength = Integer.parseInt(prefixLengthString);
056    } catch (NumberFormatException ignored) {
057    }
058    if (prefixLength <= 0) {
059      LOG.error(
060        "Invalid value for {} for table {}:{}. " + "Using the default RegionSplitRestriction",
061        PREFIX_LENGTH_KEY, tableDescriptor.getTableName(), prefixLengthString);
062    }
063  }
064
065  @Override
066  public byte[] getRestrictedSplitPoint(byte[] splitPoint) {
067    if (prefixLength > 0) {
068      // group split keys by a prefix
069      return Arrays.copyOf(splitPoint, Math.min(prefixLength, splitPoint.length));
070    } else {
071      return splitPoint;
072    }
073  }
074}