org.apache.activemq.memory.CacheEntryList Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of activemq-core Show documentation
Show all versions of activemq-core Show documentation
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.memory;
/**
* Maintains a simple linked list of CacheEntry objects. It is thread safe.
*
* @version $Revision$
*/
public class CacheEntryList {
// Points at the tail of the CacheEntry list
public final CacheEntry tail = new CacheEntry(null, null);
public CacheEntryList() {
tail.next = tail;
tail.previous = tail;
}
public void add(CacheEntry ce) {
addEntryBefore(tail, ce);
}
private void addEntryBefore(CacheEntry position, CacheEntry ce) {
assert ce.key != null && ce.next == null && ce.owner == null;
synchronized (tail) {
ce.owner = this;
ce.next = position;
ce.previous = position.previous;
ce.previous.next = ce;
ce.next.previous = ce;
}
}
public void clear() {
synchronized (tail) {
tail.next = tail;
tail.previous = tail;
}
}
public CacheEvictor createFIFOCacheEvictor() {
return new CacheEvictor() {
public CacheEntry evictCacheEntry() {
CacheEntry rc;
synchronized (tail) {
rc = tail.next;
}
return rc.remove() ? rc : null;
}
};
}
public CacheEvictor createLIFOCacheEvictor() {
return new CacheEvictor() {
public CacheEntry evictCacheEntry() {
CacheEntry rc;
synchronized (tail) {
rc = tail.previous;
}
return rc.remove() ? rc : null;
}
};
}
}