From 56239b2abe648882c297d69867015b4831b5a347 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Fri, 29 Mar 2019 01:25:11 -0400
Subject: [PATCH] Optimize Persistent Data Loading

removes Mineshaft loading legacy as we had pre 1.13.2 to avoid managing
that very large data file from legacy systems.

Previous to 1.13.2 these data files were never loaded to begin with, so they
effectively do not contain valid/relevant data.

These files take a long time to convert on large worlds and crashes the server.

Additionally, cache the result of a file being missing so we don't keep spam checking it.

diff --git a/src/main/java/net/minecraft/server/WorldPersistentData.java b/src/main/java/net/minecraft/server/WorldPersistentData.java
index 8d51af2867..e86d382c8d 100644
--- a/src/main/java/net/minecraft/server/WorldPersistentData.java
+++ b/src/main/java/net/minecraft/server/WorldPersistentData.java
@@ -39,6 +39,7 @@ public class WorldPersistentData {
 
     @Nullable
     public <T extends PersistentBase> T a(Function<String, T> function, String s) {
+        if ("Mineshaft_index".equals(s) || "Mineshaft".equals(s)) return null; // Paper - mineshaft is useless data
         T persistentbase = (T) this.data.get(s); // Paper - decompile fix
 
         if (persistentbase == null && this.e != null) {
@@ -49,14 +50,15 @@ public class WorldPersistentData {
                     persistentbase = function.apply(s); // Paper - decompile fix
                     persistentbase.a(a(this.e, this.b, s, 1631).getCompound("data"));
                     this.data.put(s, persistentbase);
-                }
+                } else this.data.put(s, NO_RESULT); // Paper
             } catch (Exception exception) {
                 WorldPersistentData.a.error("Error loading saved data: {}", s, exception);
             }
         }
 
-        return persistentbase;
+        return persistentbase == NO_RESULT ? null : persistentbase; // Paper
     }
+    private static final PersistentBase NO_RESULT = new ForcedChunk("chunks"); // Paper
 
     public void a(String s, PersistentBase persistentbase) {
         this.data.put(s, persistentbase);
@@ -126,6 +128,7 @@ public class WorldPersistentData {
     }
 
     public static NBTTagCompound a(IDataManager idatamanager, DimensionManager dimensionmanager, String s, int i) throws IOException {
+        if ("Mineshaft".equals(s) || "Mineshaft_index".equals(s)) return new NBTTagCompound(); // Paper
         File file = idatamanager.getDataFile(dimensionmanager, s);
         FileInputStream fileinputstream = new FileInputStream(file);
         Throwable throwable = null;
diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
index 5c2421ac38..ee071ba2f6 100644
--- a/src/main/java/net/minecraft/server/WorldServer.java
+++ b/src/main/java/net/minecraft/server/WorldServer.java
@@ -80,7 +80,7 @@ public class WorldServer extends World implements IAsyncTaskHandler {
         this.P();
         this.Q();
         this.getWorldBorder().a(minecraftserver.au());
-        MCUtil.scheduleAsyncTask(() -> this.getChunkProvider().chunkLoader.getPersistentStructureLegacy(dimensionmanager, worldMaps)); // Paper
+        MCUtil.scheduleAsyncTask(() -> this.getChunkProvider().chunkLoader.getPersistentStructureLegacy(worldProvider.getDimensionManager(), worldMaps)); // Paper
     }
 
     public WorldServer i_() {
-- 
2.21.0