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.master.balancer;
019
020import java.util.Comparator;
021import org.apache.hadoop.hbase.client.RegionInfo;
022
023/**
024 * The following comparator assumes that RegionId from HRegionInfo can represent the age of the
025 * region - larger RegionId means the region is younger. This comparator is used in balanceCluster()
026 * to account for the out-of-band regions which were assigned to the server after some other region
027 * server crashed.
028 */
029class RegionInfoComparator implements Comparator<RegionInfo> {
030  @Override
031  public int compare(RegionInfo l, RegionInfo r) {
032    long diff = r.getRegionId() - l.getRegionId();
033    if (diff < 0) return -1;
034    if (diff > 0) return 1;
035    return 0;
036  }
037}