Paper/patches/server/0366-Fire-PlayerJoinEvent-when-Player-is-actually-ready.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Sun, 19 Apr 2020 00:05:46 -0400
Subject: [PATCH] Fire PlayerJoinEvent when Player is actually ready

For years, plugin developers have had to delay many things they do
inside of the PlayerJoinEvent by 1 tick to make it actually work.

This all boiled down to 1 reason why: The event fired before the
player was fully ready and joined to the world!

Additionally, if that player logged out on a vehicle, the event
fired before the vehicle was even loaded, so that plugins had no
access to the vehicle during this event either.

This change finally fixes this issue, fully preparing the player
into the world as a fully ready entity, vehicle included.

There should be no plugins that break because of this change, but might
improve consistency with other plugins instead.

For example, if 2 plugins listens to this event, and the first one
teleported the player in the event, then the 2nd plugin actually
would be getting a valid player!

This was very non deterministic. This change will ensure every plugin
receives a deterministic result, and should no longer require 1 tick
delays anymore.

== AT ==
public net.minecraft.server.level.ChunkMap addEntity(Lnet/minecraft/world/entity/Entity;)V

diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index e3146ae94ae55764fcd7ec650a44d457889c179d..9ddad716d641d649e09c094795240bd2e8c926b9 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -996,6 +996,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
             return;
         }
         // Paper end - ignore and warn about illegal addEntity calls instead of crashing server
+        if (entity instanceof ServerPlayer && ((ServerPlayer) entity).supressTrackerForLogin) return; // Paper - Fire PlayerJoinEvent when Player is actually ready; Delay adding to tracker until after list packets
         if (!(entity instanceof EnderDragonPart)) {
             EntityType<?> entitytypes = entity.getType();
             int i = entitytypes.clientTrackingRange() * 16;
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 0a75cba1b0b5a85826bd60615e3f09d2f41cc6a3..b5dcb539548ca35d7c8a076d474a5c679a61c071 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -271,6 +271,7 @@ public class ServerPlayer extends Player {
     public double maxHealthCache;
     public boolean joining = true;
     public boolean sentListPacket = false;
+    public boolean supressTrackerForLogin = false; // Paper - Fire PlayerJoinEvent when Player is actually ready
     public String kickLeaveMessage = null; // SPIGOT-3034: Forward leave message to PlayerQuitEvent
     // CraftBukkit end
     public boolean isRealPlayer; // Paper
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index c04db4712ac4127cffe250e404eed9198b377429..4be466a21fb1fb936e1eaa6351e30a53c7b5cbb4 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -295,6 +295,12 @@ public abstract class PlayerList {
         this.playersByUUID.put(player.getUUID(), player);
         // this.broadcastAll(ClientboundPlayerInfoUpdatePacket.createPlayerInitializing(List.of(entityplayer))); // CraftBukkit - replaced with loop below
 
+        // Paper start - Fire PlayerJoinEvent when Player is actually ready; correctly register player BEFORE PlayerJoinEvent, so the entity is valid and doesn't require tick delay hacks
+        player.supressTrackerForLogin = true;
+        worldserver1.addNewPlayer(player);
+        this.server.getCustomBossEvents().onPlayerConnect(player); // see commented out section below worldserver.addPlayerJoin(entityplayer);
+        mountSavedVehicle(player, worldserver1, nbttagcompound);
+        // Paper end - Fire PlayerJoinEvent when Player is actually ready
         // CraftBukkit start
         CraftPlayer bukkitPlayer = player.getBukkitEntity();
 
@@ -333,6 +339,8 @@ public abstract class PlayerList {
             player.connection.send(ClientboundPlayerInfoUpdatePacket.createPlayerInitializing(List.of(entityplayer1)));
         }
         player.sentListPacket = true;
+        player.supressTrackerForLogin = false; // Paper - Fire PlayerJoinEvent when Player is actually ready
+        ((ServerLevel)player.level()).getChunkSource().chunkMap.addEntity(player); // Paper - Fire PlayerJoinEvent when Player is actually ready; track entity now
         // CraftBukkit end
 
         player.getEntityData().refresh(player); // CraftBukkit - BungeeCord#2321, send complete data to self on spawn
@@ -355,6 +363,11 @@ public abstract class PlayerList {
             playerconnection.send(new ClientboundUpdateMobEffectPacket(player.getId(), mobeffect));
         }
 
+        // Paper start - Fire PlayerJoinEvent when Player is actually ready; move vehicle into method so it can be called above - short circuit around that code
+        onPlayerJoinFinish(player, worldserver1, s1);
+    }
+    private void mountSavedVehicle(ServerPlayer player, ServerLevel worldserver1, CompoundTag nbttagcompound) {
+        // Paper end - Fire PlayerJoinEvent when Player is actually ready
         if (nbttagcompound != null && nbttagcompound.contains("RootVehicle", 10)) {
             CompoundTag nbttagcompound1 = nbttagcompound.getCompound("RootVehicle");
             // CraftBukkit start
@@ -403,6 +416,10 @@ public abstract class PlayerList {
             }
         }
 
+        // Paper start - Fire PlayerJoinEvent when Player is actually ready
+    }
+    public void onPlayerJoinFinish(ServerPlayer player, ServerLevel worldserver1, String s1) {
+        // Paper end - Fire PlayerJoinEvent when Player is actually ready
         player.initInventoryMenu();
         // CraftBukkit - Moved from above, added world
         // Paper start - Configurable player collision; Add to collideRule team if needed