Prevent unloading worlds with pending player logins

Logging into an unloaded world isn't going to end well.
This may fix the cases of people seeing errors about regionfiles
being closed, as loading chunks in an unloaded world will cause this
as the regionfile cache is closed but not cleared.

patches/server/Load-Chunks-for-Login-Asynchronously.patch

@@ -4,6 +4,26 @@ Date: Sun, 19 Apr 2020 04:28:29 -0400
 Subject: [PATCH] Load Chunks for Login Asynchronously
 
 
+diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
++++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
+@@ -0,0 +0,0 @@ import org.bukkit.event.world.GenericGameEvent;
+ import org.bukkit.event.world.TimeSkipEvent;
+ // CraftBukkit end
+ import it.unimi.dsi.fastutil.ints.IntArrayList; // Paper
++import it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet; // Paper
+ 
+ public class ServerLevel extends Level implements WorldGenLevel {
+ 
+@@ -0,0 +0,0 @@ public class ServerLevel extends Level implements WorldGenLevel {
+         return this.getServer().getPlayerList().getPlayer(uuid);
+     }
+     // Paper end
++    public final ReferenceOpenHashSet<ServerPlayer> pendingLogin = new ReferenceOpenHashSet<>(); // Paper
+ 
+     // Add env and gen to constructor, IWorldDataServer -> WorldDataServer
+     public ServerLevel(MinecraftServer minecraftserver, Executor executor, LevelStorageSource.LevelStorageAccess convertable_conversionsession, PrimaryLevelData iworlddataserver, ResourceKey<Level> resourcekey, LevelStem worlddimension, ChunkProgressListener worldloadlistener, boolean flag, long i, List<CustomSpawner> list, boolean flag1, org.bukkit.World.Environment env, org.bukkit.generator.ChunkGenerator gen, org.bukkit.generator.BiomeProvider biomeProvider) {
 diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -151,6 +171,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          this.server.invalidateStatus();
 +        // Paper start - async load spawn in chunk
 +        ServerLevel finalWorldserver = worldserver1;
++        finalWorldserver.pendingLogin.add(player);
 +        int chunkX = loc.getBlockX() >> 4;
 +        int chunkZ = loc.getBlockZ() >> 4;
 +        final net.minecraft.world.level.ChunkPos pos = new net.minecraft.world.level.ChunkPos(chunkX, chunkZ);
@@ -171,6 +192,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +                    player, finalWorldserver, connection, playerconnection,
 +                    nbttagcompound, s1, lastKnownName
 +                );
++                finalWorldserver.pendingLogin.remove(player);
 +            };
 +        });
 +    }
@@ -252,3 +274,16 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  
          Iterator iterator = list.iterator();
  
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+@@ -0,0 +0,0 @@ public final class CraftServer implements Server {
+             return false;
+         }
+ 
+-        if (handle.players().size() > 0) {
++        if (handle.players().size() > 0 || handle.pendingLogin.size() > 0) { // Paper
+             return false;
+         }
+ 

patches/server/Optimise-nearby-player-lookups.patch

@@ -109,9 +109,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 --- a/src/main/java/net/minecraft/server/level/ServerLevel.java
 +++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
 @@ -0,0 +0,0 @@ public class ServerLevel extends Level implements WorldGenLevel {
-         return this.getServer().getPlayerList().getPlayer(uuid);
-     }
      // Paper end
+     public final ReferenceOpenHashSet<ServerPlayer> pendingLogin = new ReferenceOpenHashSet<>(); // Paper
+ 
 +    // Paper start - optimise checkDespawn
 +    public final List<ServerPlayer> playersAffectingSpawning = new java.util.ArrayList<>();
 +    // Paper end - optimise checkDespawn
@@ -189,9 +189,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        return ret;
 +    }
 +    // Paper end - optimise get nearest players for entity AI
- 
++
      // Add env and gen to constructor, IWorldDataServer -> WorldDataServer
      public ServerLevel(MinecraftServer minecraftserver, Executor executor, LevelStorageSource.LevelStorageAccess convertable_conversionsession, PrimaryLevelData iworlddataserver, ResourceKey<Level> resourcekey, LevelStem worlddimension, ChunkProgressListener worldloadlistener, boolean flag, long i, List<CustomSpawner> list, boolean flag1, org.bukkit.World.Environment env, org.bukkit.generator.ChunkGenerator gen, org.bukkit.generator.BiomeProvider biomeProvider) {
+         // Holder holder = worlddimension.typeHolder(); // CraftBukkit - decompile error
 @@ -0,0 +0,0 @@ public class ServerLevel extends Level implements WorldGenLevel {
      }