Set value of isAutoStartup for DefaultMessageListenerContainerCoordinator

[stephencassidy-r7]

Hi,

Another edge case! As part of our applications, we use netflix-archaius for dynamic configuration at runtime - in this case, to control whether a queue listener is enabled or not, and to change if needed.

To do this, I have extended the DefaultMessageListenerContainerCoordinator to accept a small properties holder class that is used to determine the value of isAutoStartup, and add callbacks to properties to call start|stopContainer(identifier) to try and match the pattern used for creating other containers etc -

interface MessageListenerContainerCoordinatorProperties {
    /**
     * @return Whether the {@link MessageListenerContainerCoordinator}'s {@link MessageListenerContainerCoordinator#startAllContainers()} will be invoked by Spring.
     */
    boolean isAutoStartContainersEnabled();
}

@Value
@Builder(toBuilder = true)
class DefaultMessageListenerContainerCoordinatorProperties implements MessageListenerContainerCoordinatorProperties {
    Boolean isAutoStartContainersEnabled;
    
    @Override
    public boolean isAutoStartContainersEnabled() {
        return isAutoStartContainersEnabled;
    }
}

class ExtendedDefaultMessageListenerContainerCoordinator extends DefaultMessageListenerContainerCoordinator {
    private final MessageListenerContainerCoordinatorProperties properties;

    public ExtendedDefaultMessageListenerContainerCoordinator(final List<MessageListenerContainerFactory> factories, final MessageListenerContainerCoordinatorProperties properties) {
        super(factories);

        this.properties = properties;
    }

   // Used to get a list of all containers so we can build the property callbacks...
    public Collection<String> getContainerIdentifiers() {
        return getContainers().stream()
            .map(MessageListenerContainer::getIdentifier)
            .collect(toUnmodifiableSet());
    }

    @Override
    public boolean isAutoStartup() {
        return properties.isAutoStartContainersEnabled();
    }
}

class MessageListenerContainerLifecycleController implements SmartLifecycle {
    private final DefaultMessageListenerContainerCoordinator coordinator;
    private final Map<String, DynamicBooleanProperty> containerEnabled;

    public MessageListenerContainerLifecycleController(final DefaultMessageListenerContainerCoordinator coordinator) {
        this.coordinator = coordinator;
        /**
         * Create all the properties and callbacks for each container identifier returned from 
         * {@link ExtendedDefaultMessageListenerContainerCoordinator#getContainerIdentifiers()} on each to invoke the 
         * @{@link MessageListenerContainerCoordinator#startContainer(String)} or 
         * @{@link MessageListenerContainerCoordinator#stopContainer(String)}} depending on the value...
         */
        this.containerEnabled = createContainerLifecycleCallbacks(coordinator);
    }

    @Override
    public void start() {
        containerEnabled.forEach((identifier, enabled) -> {
            if (enabled.getValue()) {
                coordinator.startContainer(identifier);
            }
        });
    }

    @Override
    public void stop() {
        coordinator.stopAllContainers();
    }

    @Override
    public boolean isRunning() {}
}

Another tweak that would help is being able to return a collection of all identifiers if possible 😄 Currently I have these classes sitting under the same package as the original to access the getContainers() method - other than this the library does everything I needed and more, nice to get a consumer going with a few annotations!

If there is a better way to raise these let me know - technically this is not an issue or bug!

[JaidenAshmore]

Perfect timing, I have been looking for something to do this weekend!

Will take a look at this and get back to you, the request sounds solid and I think it can be done pretty easily 😃

[JaidenAshmore]

Release Notes

Improves the DefaultMessageListenerContainerCoordinator by allowing the auto startup of the containers to be configured. For more information see the Spring - How to prevent containers starting on startup guide.

Adds a getContainers method to the MessageListenerContainerCoordinator to allow for smarter configuration of the containers during runtime.