Class MutableHandler<M>

java.lang.Object
io.fluxzero.sdk.tracking.handling.MutableHandler<M>
Type Parameters:
M - the message type this handler supports
All Implemented Interfaces:
Handler<M>
public class MutableHandler<M> extends Object implements Handler<M>
A specialized Handler that maintains and mutates an internal delegate instance.

This handler is designed for use cases where the state of the handler may evolve dynamically across message invocations. It is particularly suited for temporarily scoped objects (e.g. sagas, user sessions).

Behavior

When a handler method returns an instance of the handler’s target class, this instance is stored as the new delegate: 
Object result = method.invoke(target);
if (result instanceof MyHandler) {
    target = result; // promote new version
}

If the method returns null and the method's return type matches the target class, the internal target is cleared, and any registered delete callbacks are triggered.

Lifecycle Hooks

A delete callback can be registered using onDelete(Runnable) to perform cleanup when the handler deletes its state (i.e., returns null).

  • Constructor Details

    • MutableHandler

      public MutableHandler()

  • Method Details

    • getInvoker

      public Optional<HandlerInvoker> getInvoker(M message)
      Description copied from interface: Handler
      Returns a HandlerInvoker capable of processing the given message, if available.
      Specified by:
      getInvoker in interface Handler<M>
      Parameters:
      message - the message to be handled
      Returns:
      an optional HandlerInvoker if this handler can handle the message; otherwise Optional.empty()

    • instantiateTarget

      public MutableHandler<M> instantiateTarget()
      Creates a new target using its no-argument constructor, replaces the current target, and returns this handler.

    • isEmpty

      public boolean isEmpty()
      Returns whether this handler currently has no target instance.

    • onDelete

      public Registration onDelete(Runnable callback)
      Registers a callback for target deletion and returns a registration that removes the callback.