Kevin

Extremely fast event system

Originally made for LavaHack

Notes

Event posting is very fast, but subscribing/unsubscribing maybe slow(idk i didnt test)

I recommend using it only if you dont care about subscribing/unsubscribing timing

How it works?

The main problem with any standard event system is timing of event posting

There are 2 reasons of this problem

The first reason is timing for finding collection of listeners for some posted event

The second reason is timing for iterating and invoking every listener from this collection

Solution to the first problem is binding collection as static thing directly to class of event

Solution to the second problem is combining lambdas of listeners from the collection into one, but it may cause long timing for subscribing/unsubscribing listeners, but we dont care okay?

Examples

Creating class of event

Kotlin

import lavahack.kevin.EventBus

class TestEvent {
    //
    
    companion object {
        val BUS = EventBus<TestEvent>()
    }
}

Java

import lavahack.kevin.EventBus;

public record TestEvent(/*...*/) {
    //
    
    public static final EventBus<TestEvent> BUS = new EventBus<>();
}

Creating listeners

Kotlin

import lavahack.kevin.Listener

val listenerWithDefaultPriority = Listener<TestEvent> { event -> /*action or idk*/ }
val listenerWithCustomPriority = Listener<TestEvent>(/*integer that means priority*/) { event -> /*action or idk*/ }

Java

import lavahack.kevin.Listener;

Listener<TestEvent> listenerWithDefaultPriority = new Listener<>(event -> /*action or idk*/);
Listener<TestEvent> listenerWithCustomPriority = new Listener<>(/*integer that means priority*/, event -> /*action or idk*/);

Actions with event

Kotlin

//Subscribing listener
TestEvent.BUS.subscribe(listener)

//Unsubscribing listener
TestEvent.BUS.unsubscribe(listener)

//Posting event
TestEvent.BUS.post(event)

Java

//Subscribing listener
TestEvent.BUS.subscribe(listener);

//Unsubscribing listener
TestEvent.BUS.unsubscribe(listener);

//Posting event
TestEvent.BUS.post(event);

Benchmark

This benchmark shows average time of posting test event when 200 listeners are subscribed

Event system	Average time(ns/op)
Kevin	7387 ± 317
Norbit	19455 ± 17022
Orbit	17685 ± 8369
Alpine	57519 ± 330174