Paper/patches/server/0339-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 40e48c3f1199b127066732e3c8a6d40c232215b2..f00839eab02277bf10b742c88fadc4aa9e89e7e0 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -678,12 +678,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
             worldProperties.setSpawn(BlockPos.ZERO.above(80), 0.0F);
         } else {
             ChunkGenerator chunkgenerator = world.getChunkSource().getGenerator();
-            BiomeSource worldchunkmanager = chunkgenerator.getBiomeSource();
-            Random random = new Random(world.getSeed());
-            BlockPos blockposition = worldchunkmanager.findBiomeHorizontal(0, world.getSeaLevel(), 0, 256, (biomebase) -> {
-                return biomebase.getMobSettings().playerSpawnFriendly();
-            }, random);
-            ChunkPos chunkcoordintpair = blockposition == null ? new ChunkPos(0, 0) : new ChunkPos(blockposition);
+            // Paper start - moved down
             // CraftBukkit start
             if (world.generator != null) {
                 Random rand = new Random(world.getSeed());
@@ -699,6 +694,15 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
                 }
             }
             // 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
+            BiomeSource worldchunkmanager = chunkgenerator.getBiomeSource();
+            Random random = new Random(world.getSeed());
+            BlockPos blockposition = worldchunkmanager.findBiomeHorizontal(0, world.getSeaLevel(), 0, 256, (biomebase) -> {
+                return biomebase.getMobSettings().playerSpawnFriendly();
+            }, random);
+            ChunkPos chunkcoordintpair = blockposition == null ? new ChunkPos(0, 0) : new ChunkPos(blockposition);
+            // Paper end
 
             if (blockposition == null) {
                 MinecraftServer.LOGGER.warn("Unable to find spawn biome");