From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Bjarne Koll <lynxplay101@gmail.com>
Date: Sun, 19 Feb 2023 16:14:28 +0100
Subject: [PATCH] KTP: Allow unknown event thread execution

Original license: GPL v3
Original project: https://github.com/lynxplay/ktp

This patch allows events to actively define that they may or may not be
called on the main thread of the server.
This is preferred over passing the "asyncness" of the event as async
bool parameter to the event instance every time.

diff --git a/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java b/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java
index a1c9726d25479b5326fe2fa2b0f5a98d6b2da4c5..06dfd0b27ac0006a2be07f54a0702519a691c6ec 100644
--- a/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java
+++ b/src/main/java/io/papermc/paper/plugin/manager/PaperEventManager.java
@@ -35,11 +35,17 @@ class PaperEventManager {
 
     // SimplePluginManager
     public void callEvent(@NotNull Event event) {
-        if (event.isAsynchronous() && this.server.isPrimaryThread()) {
+        // KTP start - Optimise spigot event bus
+        if (event.asynchronous() != net.kyori.adventure.util.TriState.NOT_SET) {
+        final boolean onPrimaryThread = this.server.isPrimaryThread();
+        final boolean isAsync = event.isAsynchronous();
+        if (isAsync && onPrimaryThread) {
             throw new IllegalStateException(event.getEventName() + " may only be triggered asynchronously.");
-        } else if (!event.isAsynchronous() && !this.server.isPrimaryThread() && !this.server.isStopping()) {
+        } else if (!isAsync && !onPrimaryThread && !this.server.isStopping()) {
             throw new IllegalStateException(event.getEventName() + " may only be triggered synchronously.");
         }
+        // KTP stop - Optimise spigot event bus
+        }
 
         HandlerList handlers = event.getHandlers();
         RegisteredListener[] listeners = handlers.getRegisteredListeners();