ActiveMQ example source code file (TopicStorePrefetch.java)

This example ActiveMQ source code file (TopicStorePrefetch.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

abstractstorecursor, exception, exception, failed, logger, noncachedmessageevaluationcontext, override, override, runtimeexception, runtimeexception, string, string, subscription, topicstoreprefetch

The ActiveMQ TopicStorePrefetch.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.broker.region.cursors;

import org.apache.activemq.broker.region.Subscription;
import org.apache.activemq.broker.region.Topic;
import org.apache.activemq.command.Message;
import org.apache.activemq.command.MessageId;
import org.apache.activemq.filter.MessageEvaluationContext;
import org.apache.activemq.filter.NonCachedMessageEvaluationContext;
import org.apache.activemq.store.TopicMessageStore;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * persist pendingCount messages pendingCount message (messages awaiting disptach
 * to a consumer) cursor
 * 
 * 
 */
class TopicStorePrefetch extends AbstractStoreCursor {
    private static final Logger LOG = LoggerFactory.getLogger(TopicStorePrefetch.class);
    private final TopicMessageStore store;
    private final String clientId;
    private final String subscriberName;
    private final Subscription subscription;
    private int currentLowestPriority;
    
    /**
     * @param topic
     * @param clientId
     * @param subscriberName
     */
    public TopicStorePrefetch(Subscription subscription,Topic topic, String clientId, String subscriberName) {
        super(topic);
        this.subscription=subscription;
        this.store = (TopicMessageStore)topic.getMessageStore();
        this.clientId = clientId;
        this.subscriberName = subscriberName;
        this.maxProducersToAudit=32;
        this.maxAuditDepth=10000;
        resetCurrentLowestPriority();
    }

    private void resetCurrentLowestPriority() {
        currentLowestPriority = 9;
    }

    public synchronized int getCurrentLowestPriority() {
        return currentLowestPriority;
    }

    public boolean recoverMessageReference(MessageId messageReference) throws Exception {
        // shouldn't get called
        throw new RuntimeException("Not supported");
    }
    
        
    @Override
    public synchronized boolean recoverMessage(Message message, boolean cached) throws Exception {
        if (LOG.isTraceEnabled()) {
            LOG.trace("recover: " + message.getMessageId() + ", priority: " + message.getPriority());
        }
        boolean recovered = false;
        MessageEvaluationContext messageEvaluationContext = new NonCachedMessageEvaluationContext();
        messageEvaluationContext.setMessageReference(message);
        if (this.subscription.matches(message, messageEvaluationContext)) {
            recovered = super.recoverMessage(message, cached);
            if (recovered) {
                currentLowestPriority = Math.min(currentLowestPriority, message.getPriority());                
            }
        }
        return recovered;      
    }
    
    @Override
    protected synchronized int getStoreSize() {
        try {
            return store.getMessageCount(clientId, subscriberName);
        } catch (Exception e) {
            LOG.error(this + " Failed to get the outstanding message count from the store", e);
            throw new RuntimeException(e);
        }
    }
    
    @Override
    protected synchronized boolean isStoreEmpty() {
        try {
            boolean empty = this.store.isEmpty();
            if (empty) {
                resetCurrentLowestPriority();
            }
            return empty;
            
        } catch (Exception e) {
            LOG.error("Failed to get message count", e);
            throw new RuntimeException(e);
        }
    }

            
    @Override
    protected void resetBatch() {
        this.store.resetBatching(clientId, subscriberName);
    }

    @Override
    public synchronized void gc() {
        super.gc();
        resetCurrentLowestPriority();
    }
    
    @Override
    protected void doFillBatch() throws Exception {
        this.store.recoverNextMessages(clientId, subscriberName,
                maxBatchSize, this);
    }

    @Override
    public String toString() {
        return "TopicStorePrefetch(" + clientId + "," + subscriberName + ")" + super.toString();
    }
}