001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.camel.processor.loadbalancer; 018 019import java.util.List; 020import java.util.Random; 021 022import org.apache.camel.Exchange; 023import org.apache.camel.Processor; 024 025public class WeightedRandomLoadBalancer extends WeightedLoadBalancer { 026 private final Random rnd = new Random(); 027 private final int distributionRatioSum; 028 private int runtimeRatioSum; 029 030 public WeightedRandomLoadBalancer(List<Integer> distributionRatioList) { 031 super(distributionRatioList); 032 int sum = 0; 033 for (Integer distributionRatio : distributionRatioList) { 034 sum += distributionRatio; 035 } 036 distributionRatioSum = sum; 037 runtimeRatioSum = distributionRatioSum; 038 } 039 040 @Override 041 protected Processor chooseProcessor(List<Processor> processors, Exchange exchange) { 042 int index = selectProcessIndex(); 043 lastIndex = index; 044 return processors.get(index); 045 } 046 047 public int selectProcessIndex() { 048 if (runtimeRatioSum == 0) { // every processor is exhausted, reload for a new distribution round 049 for (DistributionRatio distributionRatio : getRuntimeRatios()) { 050 int weight = distributionRatio.getDistributionWeight(); 051 distributionRatio.setRuntimeWeight(weight); 052 } 053 runtimeRatioSum = distributionRatioSum; 054 } 055 056 DistributionRatio selected = null; 057 int randomWeight = rnd.nextInt(runtimeRatioSum); 058 int choiceWeight = 0; 059 for (DistributionRatio distributionRatio : getRuntimeRatios()) { 060 choiceWeight += distributionRatio.getRuntimeWeight(); 061 if (randomWeight < choiceWeight) { 062 selected = distributionRatio; 063 break; 064 } 065 } 066 067 selected.setRuntimeWeight(selected.getRuntimeWeight() - 1); 068 runtimeRatioSum--; 069 070 return selected.getProcessorPosition(); 071 } 072}