ActiveMQ example source code file (UsageManagerCacheFilter.java)

This example ActiveMQ source code file (UsageManagerCacheFilter.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

atomiclong, atomiclong, cachefilter, memoryusage, memoryusage, object, object, usagemanagercachefilter, usagemanagercachefilter

The ActiveMQ UsageManagerCacheFilter.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;

import java.util.concurrent.atomic.AtomicLong;
import org.apache.activemq.usage.MemoryUsage;

/**
 * Simple CacheFilter that increases/decreases usage on a UsageManager as
 * objects are added/removed from the Cache.
 * 
 * 
 */
public class UsageManagerCacheFilter extends CacheFilter {

    private final AtomicLong totalUsage = new AtomicLong(0);
    private final MemoryUsage usage;

    public UsageManagerCacheFilter(Cache next, MemoryUsage um) {
        super(next);
        this.usage = um;
    }

    public Object put(Object key, Object value) {
        long usageValue = getUsageOfAddedObject(value);
        Object rc = super.put(key, value);
        if (rc != null) {
            usageValue -= getUsageOfRemovedObject(rc);
        }
        totalUsage.addAndGet(usageValue);
        usage.increaseUsage(usageValue);
        return rc;
    }

    public Object remove(Object key) {
        Object rc = super.remove(key);
        if (rc != null) {
            long usageValue = getUsageOfRemovedObject(rc);
            totalUsage.addAndGet(-usageValue);
            usage.decreaseUsage(usageValue);
        }
        return rc;
    }

    protected long getUsageOfAddedObject(Object value) {
        return 1;
    }

    protected long getUsageOfRemovedObject(Object value) {
        return 1;
    }

    public void close() {
        usage.decreaseUsage(totalUsage.get());
    }
}