Paper/Spigot-Server-Patches/0381-Do-less-work-if-we-have-a-custom-Bukkit-generator.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Paul Sauve <paul@burngames.net>
Date: Sun, 14 Jul 2019 21:05:03 -0500
Subject: [PATCH] Do less work if we have a custom Bukkit generator

If the Bukkit generator already has a spawn, use it immediately instead
of spending time generating one that we won't use

diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 0633944364179ffb9b9fdd0400d82fd5b2ab3892..41c4b2df34faa95afdd2d35b0bac021d77c56884 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -512,11 +512,7 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
         } else if (flag1) {
             iworlddataserver.setSpawn(BlockPosition.ZERO.up());
         } else {
-            WorldChunkManager worldchunkmanager = chunkgenerator.getWorldChunkManager();
-            List<BiomeBase> list = worldchunkmanager.b();
-            Random random = new Random(worldserver.getSeed());
-            BlockPosition blockposition = worldchunkmanager.a(0, worldserver.getSeaLevel(), 0, 256, list, random);
-            ChunkCoordIntPair chunkcoordintpair = blockposition == null ? new ChunkCoordIntPair(0, 0) : new ChunkCoordIntPair(blockposition);
+            // Paper start - moved down
             // CraftBukkit start
             if (worldserver.generator != null) {
                 Random rand = new Random(worldserver.getSeed());
@@ -532,6 +528,14 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
                 }
             }
             // CraftBukkit end
+            // Paper start - if the generator created a spawn for us, then there is no need for us to also create a spawn -
+            // only do it if the generator did not
+            WorldChunkManager worldchunkmanager = chunkgenerator.getWorldChunkManager();
+            List<BiomeBase> list = worldchunkmanager.b();
+            Random random = new Random(worldserver.getSeed());
+            BlockPosition blockposition = worldchunkmanager.a(0, worldserver.getSeaLevel(), 0, 256, list, random);
+            ChunkCoordIntPair chunkcoordintpair = blockposition == null ? new ChunkCoordIntPair(0, 0) : new ChunkCoordIntPair(blockposition);
+            // Paper end
 
             if (blockposition == null) {
                 MinecraftServer.LOGGER.warn("Unable to find spawn biome");