ActiveMQ example source code file (CacheEntryList.java)

This example ActiveMQ source code file (CacheEntryList.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

cacheentry, cacheentry, cacheentrylist, cacheentrylist, cacheevictor, cacheevictor

The ActiveMQ CacheEntryList.java source code

/**
 * 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.
 * 
 * 
 */
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;
            }
        };
    }

}