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 */ 017 package org.apache.activemq.broker.region.group; 018 019 import org.apache.activemq.command.ConsumerId; 020 021 /** 022 * Uses hash-code buckets to associate consumers with sets of message group IDs. 023 * 024 * @version $Revision: 564679 $ 025 */ 026 public class MessageGroupHashBucket implements MessageGroupMap { 027 028 private final int bucketCount; 029 private final ConsumerId[] consumers; 030 031 public MessageGroupHashBucket(int bucketCount) { 032 this.bucketCount = bucketCount; 033 this.consumers = new ConsumerId[bucketCount]; 034 } 035 036 public void put(String groupId, ConsumerId consumerId) { 037 int bucket = getBucketNumber(groupId); 038 consumers[bucket] = consumerId; 039 } 040 041 public ConsumerId get(String groupId) { 042 int bucket = getBucketNumber(groupId); 043 return consumers[bucket]; 044 } 045 046 public ConsumerId removeGroup(String groupId) { 047 int bucket = getBucketNumber(groupId); 048 ConsumerId answer = consumers[bucket]; 049 consumers[bucket] = null; 050 return answer; 051 } 052 053 public MessageGroupSet removeConsumer(ConsumerId consumerId) { 054 MessageGroupSet answer = null; 055 for (int i = 0; i < consumers.length; i++) { 056 ConsumerId owner = consumers[i]; 057 if (owner != null && owner.equals(consumerId)) { 058 answer = createMessageGroupSet(i, answer); 059 consumers[i] = null; 060 } 061 } 062 if (answer == null) { 063 // make an empty set 064 answer = EmptyMessageGroupSet.INSTANCE; 065 } 066 return answer; 067 } 068 069 public String toString() { 070 int count = 0; 071 for (int i = 0; i < consumers.length; i++) { 072 if (consumers[i] != null) { 073 count++; 074 } 075 } 076 return "active message group buckets: " + count; 077 } 078 079 protected MessageGroupSet createMessageGroupSet(int bucketNumber, final MessageGroupSet parent) { 080 final MessageGroupSet answer = createMessageGroupSet(bucketNumber); 081 if (parent == null) { 082 return answer; 083 } else { 084 // union the two sets together 085 return new MessageGroupSet() { 086 public boolean contains(String groupID) { 087 return parent.contains(groupID) || answer.contains(groupID); 088 } 089 }; 090 } 091 } 092 093 protected MessageGroupSet createMessageGroupSet(final int bucketNumber) { 094 return new MessageGroupSet() { 095 public boolean contains(String groupID) { 096 int bucket = getBucketNumber(groupID); 097 return bucket == bucketNumber; 098 } 099 }; 100 } 101 102 protected int getBucketNumber(String groupId) { 103 int bucket = groupId.hashCode() % bucketCount; 104 // bucket could be negative 105 if (bucket < 0) { 106 bucket *= -1; 107 } 108 return bucket; 109 } 110 }