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<div align="center">
<h1>[ bus ]</h1>
Reasonably fast & simple pub-sub written for Java applications. Mainly for sequential/single-threaded applications.
<br>Did this only for experimental reasons. Contributions are welcome if you want to add or optimise something.
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# [ how to use ]

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**Step 1**: <br>
Create new event bus instance, so you can actually use all of its capabilities.
Example of how to create the instance:
```java
import net.redinginer.eventbus.EventBus;

EventBus eventBus = EventBus.create();
// subscribe, publish or unsubscribe events
```

**Step 2**: <br>
Create your first event. Events must inherit the **AbstractEvent** class, as the bus highly depends on it.
<br>Currently, the abstraction provides only one property - cancelled. But it should be enough for most apps.
<br>Example on how to create the event:
```java
import net.redinginer.eventbus.AbstractEvent;

public final class SimpleEvent extends AbstractEvent {
  
  // here, you define the properties of the event,
  // for example:
  private final String string;
  
  public SimpleEvent(String string) {
    this.string = string;
  }
  
  public String getString() {
    return this.string;
  }
}
```

**Step 3 (and last)**: <br>
Create your first listener, that can listen to events. Listeners are defined by **@Subscribe** annotation, and any method w/o it is ignored.
<br>Methods also have strict checks, for example, they can't return anything, cannot have more than 1 parameter, and the parameter type must be assignable from **AbstractEvent**.
<br>Example on how to listen for the events, publish them, and unsubscribe after:
```java
// here goes your listener class
import net.redinginer.eventbus.EventPriority;
import net.redinginer.eventbus.Subscribe;

public class SimpleListener {

@Subscribe(priority = EventPriority.HIGHEST)
  public void handleFirst(SimpleEvent event) {
    System.out.println("This event will be called, as nothing else cancels it.");
    System.out.println("Here goes the string:");
    System.out.println(event.getString());
    System.out.println("And now, we are cancelling the event.");
    event.setCancelled(true);
  }

@Subscribe(priority = EventPriority.HIGH, ignoreCancelled = true)
  public void handleSecond(SimpleEvent event) {
    System.out.println("This method won't be called when we cancelled the event.");
    System.out.println("But here goes the string:");
    System.out.println(event.getString());
  }
}

// here goes your main class
import net.redinginer.eventbus.EventBus;

EventBus eventBus = ... // the event bus instance you acquired
SimpleListener listener = new SimpleListener();
eventBus.subscribe(listener); // this subscribes the listener
eventBus.publish(new SimpleEvent("Test!")); // this publishes the event
eventBus.unsubscribe(listener); // this unsubscribes the listener (must be the same object ref!)
```

# [ benchmarks ]

| Benchmark                                                                                                                          | Mode | Cnt | Score      | Error       | Units |
|------------------------------------------------------------------------------------------------------------------------------------|------|-----|------------|-------------|-------|
| [PostBenchmark.benchmarkPublish (listenerCount = 10)](src/jmh/java/net/redinginer/eventbus/benchmark/PostBenchmark.java)          | avgt | 20  | 176.818    | ± 1.201     | ns/op |
| [PostBenchmark.benchmarkPublish (listenerCount = 100)](src/jmh/java/net/redinginer/eventbus/benchmark/PostBenchmark.java)         | avgt | 20  | 4525.797   | ± 305.273   | ns/op |
| [PostBenchmark.benchmarkPublish (listenerCount = 1000)](src/jmh/java/net/redinginer/eventbus/benchmark/PostBenchmark.java)        | avgt | 20  | 598266.246 | ± 14102.518 | ns/op |
| [SubscribeBenchmark](src/jmh/java/net/redinginer/eventbus/benchmark/SubscribeBenchmark.java)                                       | avgt | 20  | 112324.134 | ± 8671.304  | ns/op |
| [SubscribeUnsubscribeBenchmark](src/jmh/java/net/redinginer/eventbus/benchmark/SubscribeUnsubscribeBenchmark.java)                 | avgt | 20  | 115887.395 | ± 9880.149  | ns/op |

</div>

# [ additional notes ]

Project was built using Java 21 (specifically Adoptium OpenJDK 21), and Gradle 9.0.0, with the help of JMH 1.3.7.
<br>For any documentation, just look into the code, and you should figure it out pretty easily.
<br>Also, I know that there is a room of improvement (for example, in publishing, because we need to traverse the linked list now),
<br>But I wanted to test the idea of using linked-lists, as an experiment on how fast we could go.

</div>

bus

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