JmsPrefetchPolicy.java

/**
 * 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 io.hawtjms.jms;

import java.io.Serializable;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Defines the prefetch message policies for different types of consumers
 */
public class JmsPrefetchPolicy extends Object implements Serializable {

    private static final long serialVersionUID = 5298685386681646744L;

    public static final int MAX_PREFETCH_SIZE = Short.MAX_VALUE;
    public static final int DEFAULT_QUEUE_PREFETCH = 1000;
    public static final int DEFAULT_QUEUE_BROWSER_PREFETCH = 500;
    public static final int DEFAULT_DURABLE_TOPIC_PREFETCH = 100;
    public static final int DEFAULT_TOPIC_PREFETCH = MAX_PREFETCH_SIZE;

    private static final Logger LOG = LoggerFactory.getLogger(JmsPrefetchPolicy.class);

    private int queuePrefetch;
    private int queueBrowserPrefetch;
    private int topicPrefetch;
    private int durableTopicPrefetch;
    private int maxPrefetchSize = MAX_PREFETCH_SIZE;

    /**
     * Initialize default prefetch policies
     */
    public JmsPrefetchPolicy() {
        this.queuePrefetch = DEFAULT_QUEUE_PREFETCH;
        this.queueBrowserPrefetch = DEFAULT_QUEUE_BROWSER_PREFETCH;
        this.topicPrefetch = DEFAULT_TOPIC_PREFETCH;
        this.durableTopicPrefetch = DEFAULT_DURABLE_TOPIC_PREFETCH;
    }

    /**
     * Creates a new JmsPrefetchPolicy instance copied from the source policy.
     *
     * @param source
     *      The policy instance to copy values from.
     */
    public JmsPrefetchPolicy(JmsPrefetchPolicy source) {
        this.queuePrefetch = source.getQueuePrefetch();
        this.queueBrowserPrefetch = source.getQueueBrowserPrefetch();
        this.topicPrefetch = source.getTopicPrefetch();
        this.durableTopicPrefetch = source.getDurableTopicPrefetch();
    }

    /**
     * @return Returns the durableTopicPrefetch.
     */
    public int getDurableTopicPrefetch() {
        return durableTopicPrefetch;
    }

    /**
     * Sets the durable topic prefetch value, this value is limited by the max
     * prefetch size setting.
     *
     * @param durableTopicPrefetch
     *        The durableTopicPrefetch to set.
     */
    public void setDurableTopicPrefetch(int durableTopicPrefetch) {
        this.durableTopicPrefetch = getMaxPrefetchLimit(durableTopicPrefetch);
    }

    /**
     * @return Returns the queuePrefetch.
     */
    public int getQueuePrefetch() {
        return queuePrefetch;
    }

    /**
     * @param queuePrefetch
     *        The queuePrefetch to set.
     */
    public void setQueuePrefetch(int queuePrefetch) {
        this.queuePrefetch = getMaxPrefetchLimit(queuePrefetch);
    }

    /**
     * @return Returns the queueBrowserPrefetch.
     */
    public int getQueueBrowserPrefetch() {
        return queueBrowserPrefetch;
    }

    /**
     * @param queueBrowserPrefetch
     *        The queueBrowserPrefetch to set.
     */
    public void setQueueBrowserPrefetch(int queueBrowserPrefetch) {
        this.queueBrowserPrefetch = getMaxPrefetchLimit(queueBrowserPrefetch);
    }

    /**
     * @return Returns the topicPrefetch.
     */
    public int getTopicPrefetch() {
        return topicPrefetch;
    }

    /**
     * @param topicPrefetch
     *        The topicPrefetch to set.
     */
    public void setTopicPrefetch(int topicPrefetch) {
        this.topicPrefetch = getMaxPrefetchLimit(topicPrefetch);
    }

    /**
     * Gets the currently configured max prefetch size value.
     * @return the currently configured max prefetch value.
     */
    public int getMaxPrefetchSize() {
        return maxPrefetchSize;
    }

    /**
     * Sets the maximum prefetch size value.
     *
     * @param maxPrefetchSize
     *        The maximum allowed value for any of the prefetch size options.
     */
    public void setMaxPrefetchSize(int maxPrefetchSize) {
        this.maxPrefetchSize = maxPrefetchSize;
    }

    /**
     * Sets the prefetch values for all options in this policy to the set limit.  If the value
     * given is larger than the max prefetch value of this policy the new limit will be capped
     * at the max prefetch value.
     *
     * @param prefetch
     *      The prefetch value to apply to all prefetch limits.
     */
    public void setAll(int prefetch) {
        this.durableTopicPrefetch = getMaxPrefetchLimit(prefetch);
        this.queueBrowserPrefetch = getMaxPrefetchLimit(prefetch);
        this.queuePrefetch = getMaxPrefetchLimit(prefetch);
        this.topicPrefetch = getMaxPrefetchLimit(prefetch);
    }

    @Override
    public boolean equals(Object object) {
        if (object instanceof JmsPrefetchPolicy) {
            JmsPrefetchPolicy other = (JmsPrefetchPolicy) object;
            return this.queuePrefetch == other.queuePrefetch && this.queueBrowserPrefetch == other.queueBrowserPrefetch
                && this.topicPrefetch == other.topicPrefetch && this.durableTopicPrefetch == other.durableTopicPrefetch;
        }
        return false;
    }

    private int getMaxPrefetchLimit(int value) {
        int result = Math.min(value, maxPrefetchSize);
        if (result < value) {
            LOG.warn("maximum prefetch limit has been reset from " + value + " to " + MAX_PREFETCH_SIZE);
        }
        return result;
    }
}