Migrating Events from Bukkit

In Bukkit, events are handled by creating classes that implement Listener and annotating methods with @EventHandler.

In Pumpkin, event handlers are structs or objects registered explicitly via context.register_event_handler(...). Pumpkin also differentiates between Blocking and Non-blocking events to maximize server concurrency.

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Key Differences

Feature	Bukkit / Spigot	Pumpkin
Listener Declaration	@EventHandler annotation on methods	EventHandler<E> trait / interface implementation
Registration	pm.registerEvents(listener, plugin)	context.register_event_handler(handler, priority, is_blocking)
Execution Model	Main thread execution (EventPriority)	Choice between Blocking (sequential/cancellable) and Non-blocking (concurrent)
Cancellation	event.setCancelled(true)	event.cancel() on blocking events

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Blocking vs. Non-Blocking Events in Pumpkin

Unlike Bukkit where all event handlers run sequentially on the main server thread, Pumpkin lets you specify whether an event handler is blocking:

// Registration signature in Rust:
context.register_event_handler(handler, priority, is_blocking)?;

• Blocking (is_blocking = true): Executes in sequential priority order. Can modify event data (e.g. edit join message) or cancel the event.
• Non-blocking (is_blocking = false): Executes concurrently across worker threads. Ideal for logging, metrics, or external notifications where cancellation is not needed.

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Code Comparison: Player Join Event

1. Bukkit Implementation (Java)

public class JoinListener implements Listener {
    @EventHandler(priority = EventPriority.NORMAL)
    public void onPlayerJoin(PlayerJoinEvent event) {
        Player player = event.getPlayer();
        event.setJoinMessage("Welcome " + player.getName() + " to the server!");
    }
}

// In JavaPlugin:
// getServer().getPluginManager().registerEvents(new JoinListener(), this);

2. Pumpkin Implementations

Rust

use pumpkin_plugin_api::{
    Context, Plugin, PluginMetadata, Server,
    events::{EventData, EventHandler, EventPriority, PlayerJoinEvent},
    text::TextComponent,
};

struct JoinHandler;

impl EventHandler<PlayerJoinEvent> for JoinHandler {
    fn handle<'a>(
        &'a self,
        _server: Server,
        mut event: EventData<PlayerJoinEvent>,
    ) -> EventData<PlayerJoinEvent> {
        event.join_message = TextComponent::text("Welcome to the Pumpkin server!");
        event
    }
}

pub struct MyPlugin;

impl Plugin for MyPlugin {
    fn new() -> Self { MyPlugin }

    fn metadata(&self) -> PluginMetadata {
        PluginMetadata {
            name: "join_plugin".into(),
            version: "1.0.0".into(),
            authors: vec!["Developer".into()],
            description: "Join event handler".into(),
        }
    }

    fn on_load(&mut self, context: Context) -> pumpkin_plugin_api::Result<()> {
        // Register blocking event handler with Normal priority
        context.register_event_handler(JoinHandler, EventPriority::Normal, true)?;
        Ok(())
    }
}

Python

from pumpkin_api import (
    Plugin, PluginMetadata, register_plugin,
    event, server, context
)

class MyPlugin(Plugin):
    def metadata(self) -> PluginMetadata:
        return PluginMetadata(name="join_plugin", version="1.0.0", authors=["Dev"], description="Join event")

    def on_load(self, ctx: context.Context) -> None:
        self.register_event(ctx, event.EventType.PLAYER_JOIN_EVENT, self.on_player_join)

    def on_player_join(self, srv: server.Server, evt: event.PlayerJoinEventData) -> event.PlayerJoinEventData:
        print(f"Player joined!")
        return evt

register_plugin(MyPlugin)