https://issues.apache.org/jira/browse/AMQ-6151 - retain list for redeliveries and combine for dispatch/iteration such that redeliveries retain per priority order after prefetch

activemq-broker/src/main/java/org/apache/activemq/broker/region/cursors/QueueDispatchPendingList.java

@@ -40,7 +40,6 @@ public class QueueDispatchPendingList implements PendingList {
 
     private PendingList pagedInPendingDispatch = new OrderedPendingList();
     private PendingList redeliveredWaitingDispatch = new OrderedPendingList();
-    // when true use one PrioritizedPendingList for everything
     private boolean prioritized = false;
 
 
@@ -105,6 +104,38 @@ public class QueueDispatchPendingList implements PendingList {
 
     @Override
     public Iterator<MessageReference> iterator() {
+        if (prioritized && hasRedeliveries()) {
+            final QueueDispatchPendingList delegate = this;
+            final PrioritizedPendingList  priorityOrderedRedeliveredAndPending = new PrioritizedPendingList();
+            priorityOrderedRedeliveredAndPending.addAll(redeliveredWaitingDispatch);
+            priorityOrderedRedeliveredAndPending.addAll(pagedInPendingDispatch);
+
+            return new Iterator<MessageReference>() {
+
+                Iterator<MessageReference> combinedIterator = priorityOrderedRedeliveredAndPending.iterator();
+                MessageReference current = null;
+
+                @Override
+                public boolean hasNext() {
+                    return combinedIterator.hasNext();
+                }
+
+                @Override
+                public MessageReference next() {
+                    current = combinedIterator.next();
+                    return current;
+                }
+
+                @Override
+                public void remove() {
+                    if (current!=null) {
+                        delegate.remove(current);
+                    }
+                }
+            };
+
+        } else {
+
             return new Iterator<MessageReference>() {
 
                 Iterator<MessageReference> redeliveries = redeliveredWaitingDispatch.iterator();
@@ -131,6 +162,7 @@ public class QueueDispatchPendingList implements PendingList {
                 }
             };
         }
+    }
 
     @Override
     public boolean contains(MessageReference message) {
@@ -173,14 +205,10 @@ public class QueueDispatchPendingList implements PendingList {
     }
 
     public void addMessageForRedelivery(QueueMessageReference qmr) {
-        if (prioritized) {
-            pagedInPendingDispatch.addMessageLast(qmr);
-        } else {
         redeliveredWaitingDispatch.addMessageLast(qmr);
     }
-    }
 
     public boolean hasRedeliveries(){
-        return prioritized ? !pagedInPendingDispatch.isEmpty() : !redeliveredWaitingDispatch.isEmpty();
+        return !redeliveredWaitingDispatch.isEmpty();
     }
 }

activemq-unit-tests/src/test/java/org/apache/activemq/usecases/PriorityRedeliveryOrderTest.java

@@ -0,0 +1,210 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.usecases;
+
+import java.util.ArrayList;
+import java.util.List;
+import javax.jms.Connection;
+import javax.jms.ConnectionFactory;
+import javax.jms.Message;
+import javax.jms.MessageConsumer;
+import javax.jms.MessageProducer;
+import javax.jms.Session;
+import org.apache.activemq.ActiveMQConnection;
+import org.apache.activemq.ActiveMQConnectionFactory;
+import org.apache.activemq.broker.BrokerService;
+import org.apache.activemq.broker.region.policy.PolicyEntry;
+import org.apache.activemq.broker.region.policy.PolicyMap;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+
+/**
+ * Sends X messages with a sequence number held in a JMS property "appId"
+ * Uses all priority 4 message (normal priority)
+ * closed the consumer connection multiple times so the already prefetched messages will be available
+ * for dispatch again.
+ */
+
+public class PriorityRedeliveryOrderTest {
+
+    private static final Logger LOG = LoggerFactory.getLogger(PriorityRedeliveryOrderTest.class);
+
+    private static final String DESTINATION = "testQ1";
+    private static final int MESSAGES_TO_SEND = 1000;
+    private static final int MESSAGES_PER_CONSUMER = 200;
+    private int consumedAppId = -1;
+    private int totalConsumed;
+    BrokerService broker;
+
+    @Before
+    public void createBroker() throws Exception {
+
+        broker = new BrokerService();
+        broker.setDeleteAllMessagesOnStartup(true);
+
+        PolicyMap policyMap = new PolicyMap();
+        List<PolicyEntry> entries = new ArrayList<PolicyEntry>();
+        PolicyEntry pe = new PolicyEntry();
+
+        pe.setPrioritizedMessages(true);
+
+        pe.setQueue(">");
+        entries.add(pe);
+        policyMap.setPolicyEntries(entries);
+        broker.setDestinationPolicy(policyMap);
+
+
+        broker.addConnector("tcp://0.0.0.0:0");
+
+        broker.start();
+        broker.waitUntilStarted();
+    }
+
+    @After
+    public void stopBroker() throws Exception {
+        broker.stop();
+        broker.waitUntilStopped();
+    }
+
+    @Test
+    public void testMessageDeliveryOrderAfterPrefetch() throws Exception {
+
+        //send X messages with with a sequence number number in the message property.
+        sendMessages(MESSAGES_TO_SEND);
+
+        for (int i = 0; i < (MESSAGES_TO_SEND / MESSAGES_PER_CONSUMER); i++) {
+            totalConsumed += consumeMessages(MESSAGES_PER_CONSUMER);
+        }
+        assertEquals("number of messages consumed should be equal to number of messages sent", MESSAGES_TO_SEND, totalConsumed);
+    }
+
+    private Long sendMessages(int messageCount) throws Exception {
+
+        long numberOfMessageSent = 0;
+
+        ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(broker.getTransportConnectorByScheme("tcp").getPublishableConnectString());
+
+        Connection connection = connectionFactory.createConnection();
+        connection.start();
+
+        try {
+
+            Session producerSession = connection.createSession(true, Session.SESSION_TRANSACTED);
+            MessageProducer jmsProducer = producerSession.createProducer(producerSession.createQueue(DESTINATION));
+
+            Message sendMessage = producerSession.createTextMessage("test_message");
+
+            for (int i = 0; i < messageCount; i++) {
+
+                sendMessage.setIntProperty("appID", i);
+                jmsProducer.send(sendMessage);
+                producerSession.commit();
+                numberOfMessageSent++;
+
+            }
+
+            LOG.info(" Finished after producing : " + numberOfMessageSent);
+            return numberOfMessageSent;
+
+        } catch (Exception ex) {
+            LOG.info("Exception received producing ", ex);
+            LOG.info("finishing after exception :" + numberOfMessageSent);
+            return numberOfMessageSent;
+        } finally {
+            if (connection != null) {
+                connection.close();
+            }
+        }
+    }
+
+    /*
+     Ensure messages are consumed in the expected sequence
+     */
+
+    private int consumeMessages(int numberOfMessage) throws Exception {
+
+        LOG.info("Creating new consumer for:" + numberOfMessage);
+
+
+        int numberConsumedMessage = 0;
+        ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(broker.getTransportConnectorByScheme("tcp").getPublishableConnectString());
+        ActiveMQConnection connection = (ActiveMQConnection) connectionFactory.createConnection();
+
+        try {
+
+            connection.start();
+            Session session = connection.createSession(true, Session.SESSION_TRANSACTED);
+            MessageConsumer jmsConsumer = session.createConsumer(session.createQueue(DESTINATION));
+            boolean consume = true;
+
+
+            while (consume) {
+
+                Message message = jmsConsumer.receive(4000);
+
+                if (message == null) {
+                    LOG.info("Break on:" + numberConsumedMessage);
+                    break;
+                }
+
+
+                int newAppId = message.getIntProperty("appID");
+
+                numberConsumedMessage++;
+
+                LOG.debug("Message newAppID" + newAppId);
+
+                //check it is next appID in sequence
+
+                if (newAppId != (consumedAppId + 1)) {
+                    fail(" newAppId is " + newAppId + " expected " + (consumedAppId + 1));
+                }
+
+                //increase next AppID
+                consumedAppId = newAppId;
+
+                session.commit();
+
+                if (numberConsumedMessage == numberOfMessage) {
+                    LOG.info("closing consumer after 200 message, consumedAppID is " + consumedAppId);
+                    return numberConsumedMessage;
+                }
+
+            }
+        } finally {
+
+            if (connection != null) {
+                try {
+                    connection.close();
+                } catch (Exception ex) {
+
+                }
+            }
+        }
+        return numberConsumedMessage;
+    }
+
+}
+