Fix client lag on advancement loading (#4710)

When new advancements are added via the UnsafeValues#loadAdvancement
API, it triggers a full datapack reload when this is not necessary. The
advancement is already loaded directly into the advancement registry,
and the point of saving the advancement to the Bukkit datapack seems to
be for persistence. By removing the call to reload datapacks when an
advancement is loaded, the client no longer completely freezes up when
adding a new advancement.
To ensure the client still receives the updated advancement data, we
manually reload the advancement data for all players, which
normally takes place as a part of the datapack reloading.

Spigot-Server-Patches/0595-Fix-client-lag-on-advancement-loading.patch

@@ -0,0 +1,55 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: jmp <jasonpenilla2@me.com>
+Date: Sat, 31 Oct 2020 11:49:01 -0700
+Subject: [PATCH] Fix client lag on advancement loading
+
+When new advancements are added via the UnsafeValues#loadAdvancement
+API, it triggers a full datapack reload when this is not necessary. The
+advancement is already loaded directly into the advancement registry,
+and the point of saving the advancement to the Bukkit datapack seems to
+be for persistence. By removing the call to reload datapacks when an
+advancement is loaded, the client no longer completely freezes up when
+adding a new advancement.
+To ensure the client still receives the updated advancement data, we
+manually reload the advancement data for all players, which
+normally takes place as a part of the datapack reloading.
+
+diff --git a/src/main/java/net/minecraft/server/AdvancementDataPlayer.java b/src/main/java/net/minecraft/server/AdvancementDataPlayer.java
+index 17789407b9e86896a963a305a13357286aa5f319..ddbf8237d598f32e6e5361ca92ace268dfbec906 100644
+--- a/src/main/java/net/minecraft/server/AdvancementDataPlayer.java
++++ b/src/main/java/net/minecraft/server/AdvancementDataPlayer.java
+@@ -78,6 +78,7 @@ public class AdvancementDataPlayer {
+ 
+     }
+ 
++    public final void reload(AdvancementDataWorld advancementDataWorld) { this.a(advancementDataWorld); } // Paper - OBFHELPER
+     public void a(AdvancementDataWorld advancementdataworld) {
+         this.a();
+         this.data.clear();
+@@ -374,6 +375,7 @@ public class AdvancementDataPlayer {
+ 
+     }
+ 
++    public final void sendUpdateIfNeeded(EntityPlayer entityPlayer) { this.b(entityPlayer); } // Paper - OBFHELPER
+     public void b(EntityPlayer entityplayer) {
+         if (this.m || !this.i.isEmpty() || !this.j.isEmpty()) {
+             Map<MinecraftKey, AdvancementProgress> map = Maps.newHashMap();
+diff --git a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+index 3ebaa9463e365831de37d8fa3cc191693f5b856f..9957c65d418f39e74956d1182b8fbf539f404eb6 100644
+--- a/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
++++ b/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+@@ -282,7 +282,13 @@ public final class CraftMagicNumbers implements UnsafeValues {
+                     Bukkit.getLogger().log(Level.SEVERE, "Error saving advancement " + key, ex);
+                 }
+ 
+-                MinecraftServer.getServer().getPlayerList().reload();
++                // Paper start
++                //MinecraftServer.getServer().getPlayerList().reload();
++                MinecraftServer.getServer().getPlayerList().getPlayers().forEach(player -> {
++                    player.getAdvancementData().reload(MinecraftServer.getServer().getAdvancementData());
++                    player.getAdvancementData().sendUpdateIfNeeded(player);
++                });
++                // Paper end
+ 
+                 return bukkit;
+             }