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The ActiveMQ Message Broker and Client implementations
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.broker.region.group;
import org.apache.activemq.command.ConsumerId;
/**
* Uses hash-code buckets to associate consumers with sets of message group IDs.
*
* @version $Revision: 564679 $
*/
public class MessageGroupHashBucket implements MessageGroupMap {
private final int bucketCount;
private final ConsumerId[] consumers;
public MessageGroupHashBucket(int bucketCount) {
this.bucketCount = bucketCount;
this.consumers = new ConsumerId[bucketCount];
}
public void put(String groupId, ConsumerId consumerId) {
int bucket = getBucketNumber(groupId);
consumers[bucket] = consumerId;
}
public ConsumerId get(String groupId) {
int bucket = getBucketNumber(groupId);
return consumers[bucket];
}
public ConsumerId removeGroup(String groupId) {
int bucket = getBucketNumber(groupId);
ConsumerId answer = consumers[bucket];
consumers[bucket] = null;
return answer;
}
public MessageGroupSet removeConsumer(ConsumerId consumerId) {
MessageGroupSet answer = null;
for (int i = 0; i < consumers.length; i++) {
ConsumerId owner = consumers[i];
if (owner != null && owner.equals(consumerId)) {
answer = createMessageGroupSet(i, answer);
consumers[i] = null;
}
}
if (answer == null) {
// make an empty set
answer = EmptyMessageGroupSet.INSTANCE;
}
return answer;
}
public String toString() {
int count = 0;
for (int i = 0; i < consumers.length; i++) {
if (consumers[i] != null) {
count++;
}
}
return "active message group buckets: " + count;
}
protected MessageGroupSet createMessageGroupSet(int bucketNumber, final MessageGroupSet parent) {
final MessageGroupSet answer = createMessageGroupSet(bucketNumber);
if (parent == null) {
return answer;
} else {
// union the two sets together
return new MessageGroupSet() {
public boolean contains(String groupID) {
return parent.contains(groupID) || answer.contains(groupID);
}
};
}
}
protected MessageGroupSet createMessageGroupSet(final int bucketNumber) {
return new MessageGroupSet() {
public boolean contains(String groupID) {
int bucket = getBucketNumber(groupID);
return bucket == bucketNumber;
}
};
}
protected int getBucketNumber(String groupId) {
int bucket = groupId.hashCode() % bucketCount;
// bucket could be negative
if (bucket < 0) {
bucket *= -1;
}
return bucket;
}
}