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;
021
022import org.apache.hadoop.hbase.client.RegionInfo;
023
024/**
025 * The following comparator assumes that RegionId from HRegionInfo can represent
026 * the age of the region - larger RegionId means the region is younger. This
027 * comparator is used in balanceCluster() to account for the out-of-band regions
028 * which were assigned to the server after some other region server crashed.
029 */
030class RegionInfoComparator implements Comparator<RegionInfo> {
031  @Override
032  public int compare(RegionInfo l, RegionInfo r) {
033    long diff = r.getRegionId() - l.getRegionId();
034    if (diff < 0) return -1;
035    if (diff > 0) return 1;
036    return 0;
037  }
038}