WIP: AMQ-9855: VMTransport, Defensive copy of messages to prevent mutation

activemq-client/src/main/java/org/apache/activemq/command/ActiveMQTextMessage.java

@@ -55,8 +55,8 @@ public Message copy() {
     }
 
     private void copy(ActiveMQTextMessage copy) {
-        super.copy(copy);
-        copy.text = text;
+            super.copy(copy);
+            copy.text = this.text;
     }
 
     @Override
@@ -154,6 +154,11 @@ public void storeContent() {
     // and https://issues.apache.org/activemq/browse/AMQ-2966
     @Override
     public void clearUnMarshalledState() throws JMSException {
+        // Crucial: Store the content before we wipe the text
+        // This ensures we don't end up with BOTH being null
+        if (this.text != null && getContent() == null) {
+            storeContent();
+        }
         super.clearUnMarshalledState();
         this.text = null;
     }
@@ -175,13 +180,13 @@ public boolean isContentMarshalled() {
      *                 due to some internal error.
      */
     @Override
-    public void clearBody() throws JMSException {
+    public synchronized void clearBody() throws JMSException {
         super.clearBody();
         this.text = null;
     }
 
     @Override
-    public int getSize() {
+    public synchronized int getSize() {
         String text = this.text;
         if (size == 0 && content == null && text != null) {
             size = getMinimumMessageSize();
@@ -194,7 +199,7 @@ public int getSize() {
     }
 
     @Override
-    public String toString() {
+    public synchronized String toString() {
         try {
             String text = this.text;
             if( text == null ) {

activemq-unit-tests/src/test/java/org/apache/activemq/command/ActiveMQTextMessageStressTest.java

@@ -0,0 +1,187 @@
+/**
+ * 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.command;
+
+import jakarta.jms.Connection;
+import jakarta.jms.MessageConsumer;
+import jakarta.jms.Session;
+import jakarta.jms.Topic;
+import jakarta.jms.MessageProducer;
+import jakarta.jms.TextMessage;
+import jakarta.jms.JMSException;
+
+import org.apache.activemq.ActiveMQConnectionFactory;
+import org.apache.activemq.broker.BrokerService;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.List;
+import java.util.ArrayList;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertEquals;
+
+public class ActiveMQTextMessageStressTest {
+
+    private static final Logger LOG = LoggerFactory.getLogger(ActiveMQTextMessageStressTest.class);
+    private BrokerService broker;
+    private Connection connection;
+
+    @Before
+    public void setUp() throws Exception {
+        broker = new BrokerService();
+        broker.setPersistent(false);
+        broker.setUseJmx(false);
+        broker.addConnector("vm://localhost");
+        broker.start();
+
+        ActiveMQConnectionFactory cf = new ActiveMQConnectionFactory("vm://localhost");
+        connection = cf.createConnection();
+        connection.setClientID("HIGH_CONC_TEST");
+        connection.start();
+    }
+
+    @After
+    public void tearDown() throws Exception {
+        if (connection != null) {
+            connection.close();
+        }
+        if (broker != null) {
+            broker.stop();
+        }
+    }
+
+    @Test
+    public void testConcurrentProducersAndConsumers() throws Exception {
+        final int MESSAGE_COUNT = 50;
+        final int PRODUCERS = 2;
+        final int DURABLE_CONSUMERS = 2;
+        final int NON_DURABLE_CONSUMERS = 2;
+        final int TOTAL_CONSUMERS = DURABLE_CONSUMERS + NON_DURABLE_CONSUMERS;
+
+        Session tmpSession = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
+        Topic topic = tmpSession.createTopic("HIGH_CONC.TOPIC");
+
+        List<MessageConsumer> consumers = new ArrayList<>();
+        List<Session> consumerSessions = new ArrayList<>();
+
+        for (int i = 1; i <= DURABLE_CONSUMERS; i++) {
+            Session s = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
+            consumers.add(s.createDurableSubscriber(topic, "Durable-" + i));
+            consumerSessions.add(s);
+        }
+        for (int i = 1; i <= NON_DURABLE_CONSUMERS; i++) {
+            Session s = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
+            consumers.add(s.createConsumer(topic));
+            consumerSessions.add(s);
+        }
+
+        ExecutorService executor = Executors.newFixedThreadPool(PRODUCERS + TOTAL_CONSUMERS);
+        CountDownLatch producerLatch = new CountDownLatch(PRODUCERS);
+
+        // Producers
+        for (int p = 1; p <= PRODUCERS; p++) {
+            final int producerId = p;
+            executor.submit(() -> {
+                try {
+                    Session s = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
+                    MessageProducer producer = s.createProducer(topic);
+                    for (int m = 1; m <= MESSAGE_COUNT; m++) {
+                        TextMessage msg = s.createTextMessage("P" + producerId + "-M" + m);
+                        producer.send(msg);
+                    }
+                    s.close();
+                } catch (JMSException e) {
+                    LOG.error("Producer error", e);
+                } finally {
+                    producerLatch.countDown();
+                }
+            });
+        }
+
+        // Consumers
+        List<Future<List<TextMessage>>> consumerFutures = new ArrayList<>();
+        for (MessageConsumer consumer : consumers) {
+            consumerFutures.add(executor.submit(() -> {
+                List<TextMessage> received = new ArrayList<>();
+                try {
+                    for (int i = 0; i < MESSAGE_COUNT * PRODUCERS; i++) {
+                        TextMessage msg = (TextMessage) consumer.receive(10000);
+                        assertNotNull("Consumer should receive a message", msg);
+
+                        // Hammer the message to trigger race condition on unmarshalling
+                        for (int j = 0; j < 10; j++) {
+                            String txt = msg.getText();
+                            assertNotNull("Text should never be null during stress", txt);
+                            // Clear state to force unmarshalling on the next call
+                            ((ActiveMQTextMessage) msg).clearUnMarshalledState();
+                        }
+                        received.add(msg);
+                    }
+                } catch (Exception e) {
+                    LOG.error("Consumer error", e);
+                }
+                return received;
+            }));
+        }
+
+        producerLatch.await(30, TimeUnit.SECONDS);
+
+        List<List<TextMessage>> allConsumed = new ArrayList<>();
+        for (Future<List<TextMessage>> f : consumerFutures) {
+            allConsumed.add(f.get(30, TimeUnit.SECONDS));
+        }
+
+        // Validate independent instances and data integrity
+        for (int i = 0; i < allConsumed.size(); i++) {
+            List<TextMessage> consumerMsgs = allConsumed.get(i);
+            assertEquals("Consumer " + i + " did not receive all messages", MESSAGE_COUNT * PRODUCERS, consumerMsgs.size());
+
+            for (int j = i + 1; j < allConsumed.size(); j++) {
+                List<TextMessage> otherMsgs = allConsumed.get(j);
+
+                for (int k = 0; k < consumerMsgs.size(); k++) {
+                    TextMessage m1 = consumerMsgs.get(k);
+                    TextMessage m2 = otherMsgs.get(k);
+
+                    assertNotSame("Message wrappers MUST be different instances across consumers", m1, m2);
+                    assertEquals("Content must match", m1.getText(), m2.getText());
+                    assertNotNull("Content should not be null", m1.getText());
+                }
+            }
+        }
+
+        executor.shutdown();
+        if (!executor.awaitTermination(5, TimeUnit.SECONDS)) {
+            executor.shutdownNow();
+        }
+
+        for (Session s : consumerSessions) {
+            s.close();
+        }
+        tmpSession.close();
+    }
+}