Paper/patches/server/0346-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 5732aded2e4dbeea84dbe6ebac71c2ad5ce4729a..d1247df5c51b0d377a27ea7cc5b5a2d1f1bf9b32 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -1315,6 +1315,7 @@ 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 df6fb7dd6015ce6e558a97598c822243dcc1c284..b808d9c710d6cd59ac34ea537f603fd4002073d0 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -288,6 +288,7 @@ public class ServerPlayer extends net.minecraft.world.entity.player.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 511333fc0f00c5de544f5e10ddf4c5262fdf5ee3..cbad29d23f5c90dadd7d442372247e7befe18e49 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -297,6 +297,12 @@ 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);
+        this.mountSavedVehicle(player, worldserver1, optional);
+        // Paper end - Fire PlayerJoinEvent when Player is actually ready
         // CraftBukkit start
         CraftPlayer bukkitPlayer = player.getBukkitEntity();
 
@@ -335,6 +341,8 @@ 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.refreshEntityData(player); // CraftBukkit - BungeeCord#2321, send complete data to self on spawn
@@ -350,6 +358,11 @@ public abstract class PlayerList {
         worldserver1 = player.serverLevel(); // CraftBukkit - Update in case join event changed it
         // CraftBukkit end
         this.sendActivePlayerEffects(player);
+        // Paper start - Fire PlayerJoinEvent when Player is actually ready; move vehicle into method so it can be called above - short circuit around that code
+        this.onPlayerJoinFinish(player, worldserver1, s1);
+    }
+    private void mountSavedVehicle(ServerPlayer player, ServerLevel worldserver1, Optional<CompoundTag> optional) {
+        // Paper end - Fire PlayerJoinEvent when Player is actually ready
         if (optional.isPresent() && ((CompoundTag) optional.get()).contains("RootVehicle", 10)) {
             CompoundTag nbttagcompound = ((CompoundTag) optional.get()).getCompound("RootVehicle");
             ServerLevel finalWorldServer = worldserver1; // CraftBukkit - decompile error
@@ -396,6 +409,10 @@ 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