Don't allow acquire after the callback returns. Add more logging

Author: sbSteveK

src/main/java/software/amazon/awssdk/crt/mqtt5/Mqtt5ClientOptions.java

@@ -347,13 +347,13 @@ public interface PublishEvents {
         /**
          * Called when an MQTT PUBLISH packet is received by the client.
          *
-         * <p>To take manual control of the PUBACK for a QoS 1 message, call
+         * <p>To take manual control of the publish acknowledgement for a QoS 1 message, call
          * {@link PublishReturn#acquirePublishAcknowledgementControl()} within this callback. If you do so,
-         * the client will NOT automatically send the PUBACK; you are responsible for calling
+         * the client will NOT automatically send the publish acknowledgement. You are responsible for calling
          * {@link Mqtt5Client#invokePublishAcknowledgement(Mqtt5PublishAcknowledgementControlHandle)} later.</p>
          *
-         * <p>If you do not call {@code acquirePublishAcknowledgementControl()}, the client will automatically
-         * send the PUBACK after this callback returns.</p>
+         * <p>If you do not call {@code acquirePublishAcknowledgementControl()} within the callback , 
+         * the client will automatically send the publish acknowledgement after this callback returns.</p>
          *
          * @param client The client that has received the message
          * @param publishReturn All of the data that was received from the server

src/main/java/software/amazon/awssdk/crt/mqtt5/PublishReturn.java

@@ -89,6 +89,18 @@ boolean wasControlAcquired() {
         return controlAcquired;
     }
 
+    /**
+     * Called by native/JNI code after the {@link Mqtt5ClientOptions.PublishEvents#onMessageReceived}
+     * callback returns to prevent post-callback use of
+     * {@link #acquirePublishAcknowledgementControl()}.
+     *
+     * <p>Zeroes out {@code controlId} so that any saved reference to this {@code PublishReturn}
+     * cannot call {@code acquirePublishAcknowledgementControl()} after the callback has returned.</p>
+     */
+    synchronized void invalidateAfterCallback() {
+        controlId = 0;
+    }
+
     /**
      * This is only called in JNI to make a new PublishReturn with a PUBLISH packet.
      * The controlId is the already-acquired publish acknowledgement control ID (eagerly acquired

src/native/java_class_ids.c

@@ -2256,13 +2256,20 @@ static void s_cache_mqtt5_publish_return(JNIEnv *env) {
         "(Lsoftware/amazon/awssdk/crt/mqtt5/packets/PublishPacket;J)V");
     AWS_FATAL_ASSERT(mqtt5_publish_return_properties.return_constructor_id);
     /*
-     * wasControlAcquired() - called by native code after onMessageReceived returns to determine
+     * wasControlAcquired() called by native code after onMessageReceived returns to determine
      * whether the user called acquirePublishAcknowledgementControl() during the callback.
      * Returns true if the user took manual control of the PUBACK, false otherwise.
      */
     mqtt5_publish_return_properties.return_was_control_acquired_id =
         (*env)->GetMethodID(env, mqtt5_publish_return_properties.return_class, "wasControlAcquired", "()Z");
     AWS_FATAL_ASSERT(mqtt5_publish_return_properties.return_was_control_acquired_id);
+    /*
+     * invalidateAfterCallback() called by native code after onMessageReceived returns to zero
+     * out controlId, preventing post-callback calls to acquirePublishAcknowledgementControl().
+     */
+    mqtt5_publish_return_properties.return_invalidate_after_callback_id =
+        (*env)->GetMethodID(env, mqtt5_publish_return_properties.return_class, "invalidateAfterCallback", "()V");
+    AWS_FATAL_ASSERT(mqtt5_publish_return_properties.return_invalidate_after_callback_id);
 }
 
 struct java_aws_mqtt5_on_stopped_return_properties mqtt5_on_stopped_return_properties;

src/native/java_class_ids.h

@@ -926,8 +926,9 @@ extern struct java_aws_mqtt5_publish_result_properties mqtt5_publish_result_prop
 /* mqtt5.PublishReturn */
 struct java_aws_mqtt5_publish_return_properties {
     jclass return_class;
-    jmethodID return_constructor_id;
-    jmethodID return_was_control_acquired_id;
+    jmethodID return_constructor_id;               /* (PublishPacket, long) */
+    jmethodID return_was_control_acquired_id;      /* ()Z true if user called acquirePublishAcknowledgementControl() */
+    jmethodID return_invalidate_after_callback_id; /* ()V zeroes controlId to prevent post-callback use */
 };
 extern struct java_aws_mqtt5_publish_return_properties mqtt5_publish_return_properties;