Enforce Sync Chunk Unloads

Unloading Chunks async is extremely dangerous. This will force it to main
the same way we handle async chunk loads.

Spigot-API-Patches/0048-Provide-E-TE-Chunk-count-stat-methods.patch

@@ -1,4 +1,4 @@
-From 604dc8e444593ab84281c94ca4eb334164c96ea8 Mon Sep 17 00:00:00 2001
+From 20f93fadc1651fc03cbd926370d79d191a3fe1f1 Mon Sep 17 00:00:00 2001
 From: Aikar <aikar@aikar.co>
 Date: Sat, 7 Jan 2017 15:23:03 -0500
 Subject: [PATCH] Provide E/TE/Chunk count stat methods
@@ -7,17 +7,32 @@ Provides counts without the ineffeciency of using .getEntities().size()
 which creates copy of the collections.
 
 diff --git a/src/main/java/org/bukkit/World.java b/src/main/java/org/bukkit/World.java
-index 56f50296..63cdcdb8 100644
+index 56f50296..2b6136fd 100644
 --- a/src/main/java/org/bukkit/World.java
 +++ b/src/main/java/org/bukkit/World.java
-@@ -24,6 +24,13 @@ import org.bukkit.util.Vector;
+@@ -24,6 +24,28 @@ import org.bukkit.util.Vector;
   */
  public interface World extends PluginMessageRecipient, Metadatable {
  
 +    // Paper start
++    /**
++     * @return The amount of Entities in this world
++     */
 +    int getEntityCount();
++
++    /**
++     * @return The amount of Tile Entities in this world
++     */
 +    int getTileEntityCount();
++
++    /**
++     * @return The amount of Tickable Tile Entities in this world
++     */
 +    int getTickableTileEntityCount();
++
++    /**
++     * @return The amount of Chunks in this world
++     */
 +    int getChunkCount();
 +    // Paper end
 +

Spigot-Server-Patches/0203-Enforce-Sync-Chunk-Unloads.patch

@@ -0,0 +1,31 @@
+From e8a422782bf1466348b1dcd40c75e8576b52c233 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Sat, 7 Jan 2017 16:06:44 -0500
+Subject: [PATCH] Enforce Sync Chunk Unloads
+
+Unloading Chunks async is extremely dangerous. This will force it to main
+the same way we handle async chunk loads.
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+index 1c4040760..c678718b7 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftWorld.java
+@@ -235,6 +235,7 @@ public class CraftWorld implements World {
+     }
+ 
+     private boolean unloadChunk0(int x, int z, boolean save) {
++        Boolean result = MCUtil.ensureMain("Unload Chunk", () -> { // Paper - Ensure never async
+         net.minecraft.server.Chunk chunk = world.getChunkProviderServer().getChunkIfLoaded(x, z);
+         if (chunk == null) {
+             return true;
+@@ -242,6 +243,7 @@ public class CraftWorld implements World {
+ 
+         // If chunk had previously been queued to save, must do save to avoid loss of that data
+         return world.getChunkProviderServer().unloadChunk(chunk, chunk.mustSave || save);
++        }); return result != null ? result : false; // Paper - Ensure never async
+     }
+ 
+     public boolean regenerateChunk(int x, int z) {
+-- 
+2.11.0
+