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.Collection;
021import java.util.Iterator;
022import org.apache.yetus.audience.InterfaceAudience;
023
024/**
025 * Class to be used for the subset of RegionLoad costs that should be treated as rates. We do not
026 * compare about the actual rate in requests per second but rather the rate relative to the rest of
027 * the regions.
028 */
029@InterfaceAudience.Private
030abstract class CostFromRegionLoadAsRateFunction extends CostFromRegionLoadFunction {
031
032  @Override
033  protected double getRegionLoadCost(Collection<BalancerRegionLoad> regionLoadList) {
034    Iterator<BalancerRegionLoad> iter = regionLoadList.iterator();
035    if (!iter.hasNext()) {
036      return 0;
037    }
038    double previous = getCostFromRl(iter.next());
039    if (!iter.hasNext()) {
040      return 0;
041    }
042    double cost = 0;
043    do {
044      double current = getCostFromRl(iter.next());
045      cost += current >= previous ? current - previous : current;
046      previous = current;
047    } while (iter.hasNext());
048    return Math.max(0, cost / (regionLoadList.size() - 1));
049  }
050}