Add a way of improving EventHandler immutability about chronicle-threads HOT 8 CLOSED

A perhaps even more compelling alternative would be to add an overload method EventLoop.addHandler(Supplier<? extends EventHandler>) that creates the EventHandler using the EventLoop's own execution thread. This way, thread-specific properties may be initialized in the constructor and may thus be final.

private final Thread actionThread;

...
    public TcpEventHandler(...)
        this.actionThread = Thread.currentThread();
    }

from chronicle-threads.

I like the idea very much and the Supplier mechanism sounds great.
Only thing that does concern me about the Supplier solution is that the EventHandler constructor does not know whether it is being called from the event loop thread or any old thread.

from chronicle-threads.

The contract would be that the Supplier is guaranteed to be invoked by the event loop thread.

from chronicle-threads.

Yes but my point is that there is no way for the EventHandler to know if its constructor has been called by the supplier (in EL thread) or by something else (in whatever thread) - or do you propose to replace (rather than offer as an alternative)
EventLoop#addHandler(net.openhft.chronicle.core.threads.EventHandler)
with the Supplier mechanism?

from chronicle-threads.

I agree with @JerryShea that there is no way of knowing that it is the event thread that is being used in a constructor. So, it would be better to provide the event thread as a parameter to the constructor. Also, the EventHandler:eventLoop parameter could be provided to the constructor. These two parameters are generally known by an EventLoop.

from chronicle-threads.

Added:

    /**
     * Adds a handler to this EventLoop by first invoking the provided EventHandler
     * constructor and then taking the constructed instance and providing it to
     * the {@link #addHandler(EventHandler)} method.
     * <p>
     * The BiFunction's Thread is the event thread for this EventLoop
     * The BiFunction's EventLoop is the same parameter later provided to EventHandler::eventLoop
     * <p>
     * This method improves the ability to write immutable or partly immutable EventHandler classes
     * compared with the {@link #addHandler(EventHandler)} method.
     *
     * @param constructor to invoke when creating an EventHandler
     * @param priority for the EventHandler that must match the created EventHandler's priority
     * @return closeable to use for cleaning up.
     * @throws IllegalStateException if the provided {@code priority} does not match the
     * constructed EventHandler's priority.
     */
    Closeable addHandler(@NotNull BiFunction<Thread, EventLoop, EventHandler> constructor, @NotNull HandlerPriority priority);

from chronicle-threads.

This facility is covered by the eventLoop(EventLoop) call however I have added a loopStarted() to make this clearer.

from chronicle-threads.

Released in Chronicle-Threads-2.20.43, BOM-2.20.67

from chronicle-threads.