org.apache.activemq.transport.amqp.protocol.AmqpTransferTagGenerator Maven / Gradle / Ivy
/**
* 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.transport.amqp.protocol;
import java.io.UnsupportedEncodingException;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;
/**
* Utility class that can generate and if enabled pool the binary tag values
* used to identify transfers over an AMQP link.
*/
public final class AmqpTransferTagGenerator {
public static final int DEFAULT_TAG_POOL_SIZE = 1024;
private long nextTagId;
private int maxPoolSize = DEFAULT_TAG_POOL_SIZE;
private final Set tagPool;
public AmqpTransferTagGenerator() {
this(false);
}
public AmqpTransferTagGenerator(boolean pool) {
if (pool) {
this.tagPool = new LinkedHashSet();
} else {
this.tagPool = null;
}
}
/**
* Retrieves the next available tag.
*
* @return a new or unused tag depending on the pool option.
*/
public byte[] getNextTag() {
byte[] rc;
if (tagPool != null && !tagPool.isEmpty()) {
final Iterator iterator = tagPool.iterator();
rc = iterator.next();
iterator.remove();
} else {
try {
rc = Long.toHexString(nextTagId++).getBytes("UTF-8");
} catch (UnsupportedEncodingException e) {
// This should never happen since we control the input.
throw new RuntimeException(e);
}
}
return rc;
}
/**
* When used as a pooled cache of tags the unused tags should always be returned once
* the transfer has been settled.
*
* @param data
* a previously borrowed tag that is no longer in use.
*/
public void returnTag(byte[] data) {
if (tagPool != null && tagPool.size() < maxPoolSize) {
tagPool.add(data);
}
}
/**
* Gets the current max pool size value.
*
* @return the current max tag pool size.
*/
public int getMaxPoolSize() {
return maxPoolSize;
}
/**
* Sets the max tag pool size. If the size is smaller than the current number
* of pooled tags the pool will drain over time until it matches the max.
*
* @param maxPoolSize
* the maximum number of tags to hold in the pool.
*/
public void setMaxPoolSize(int maxPoolSize) {
this.maxPoolSize = maxPoolSize;
}
}