Paper/patches/server/0418-Fix-Longstanding-Broken-behavior-of-PlayerJoinEvent.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] Fix Longstanding Broken behavior of PlayerJoinEvent

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.

diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index dfe7af5568de8d9511f18a6894026f0f1143a0ff..419e928c853d921dccc36471559962caf5006117 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -1600,6 +1600,7 @@ public class ChunkMap extends ChunkStorage implements ChunkHolder.PlayerProvider
                 .printStackTrace();
             return;
         }
+        if (entity instanceof ServerPlayer && ((ServerPlayer) entity).supressTrackerForLogin) return; // Delay adding to tracker until after list packets
         // Paper end
         if (!(entity instanceof EnderDragonPart)) {
             EntityType<?> entitytypes = entity.getType();
diff --git a/src/main/java/net/minecraft/server/level/ServerPlayer.java b/src/main/java/net/minecraft/server/level/ServerPlayer.java
index 9500fb90db765095afb1ecd91bbef6099cdc7a4b..63f20e7adf80a1b81438262087e33c3a1e63ca7f 100644
--- a/src/main/java/net/minecraft/server/level/ServerPlayer.java
+++ b/src/main/java/net/minecraft/server/level/ServerPlayer.java
@@ -237,6 +237,7 @@ public class ServerPlayer extends Player {
     public double maxHealthCache;
     public boolean joining = true;
     public boolean sentListPacket = false;
+    public boolean supressTrackerForLogin = false; // Paper
     public Integer clientViewDistance;
     // CraftBukkit end
     public PlayerNaturallySpawnCreaturesEvent playerNaturallySpawnedEvent; // Paper
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 5432ce5b86b7731fe5d06d334e4e191f2eb2f429..3a13c151066c8784fdc844e1d6310f77ff32e7f1 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -274,6 +274,12 @@ public abstract class PlayerList {
         this.playersByUUID.put(player.getUUID(), player);
         // this.sendAll(new PacketPlayOutPlayerInfo(PacketPlayOutPlayerInfo.EnumPlayerInfoAction.ADD_PLAYER, new EntityPlayer[]{entityplayer})); // CraftBukkit - replaced with loop below
 
+        // Paper start - 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
         // CraftBukkit start
         PlayerJoinEvent playerJoinEvent = new org.bukkit.event.player.PlayerJoinEvent(this.cserver.getPlayer(player), PaperAdventure.asAdventure(chatmessage)); // Paper - Adventure
         this.cserver.getPluginManager().callEvent(playerJoinEvent);
@@ -309,6 +315,8 @@ public abstract class PlayerList {
             player.connection.send(new ClientboundPlayerInfoPacket(ClientboundPlayerInfoPacket.Action.ADD_PLAYER, new ServerPlayer[] { entityplayer1}));
         }
         player.sentListPacket = true;
+        player.supressTrackerForLogin = false; // Paper
+        ((ServerLevel)player.level).getChunkSource().chunkMap.addEntity(player); // Paper - track entity now
         // CraftBukkit end
 
         player.connection.send(new ClientboundSetEntityDataPacket(player.getId(), player.getEntityData(), true)); // CraftBukkit - BungeeCord#2321, send complete data to self on spawn
@@ -334,6 +342,11 @@ public abstract class PlayerList {
             playerconnection.send(new ClientboundUpdateMobEffectPacket(player.getId(), mobeffect));
         }
 
+        // Paper start - 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
         if (nbttagcompound != null && nbttagcompound.contains("RootVehicle", 10)) {
             CompoundTag nbttagcompound1 = nbttagcompound.getCompound("RootVehicle");
             // CraftBukkit start
@@ -382,6 +395,10 @@ public abstract class PlayerList {
             }
         }
 
+        // Paper start
+    }
+    public void onPlayerJoinFinish(ServerPlayer player, ServerLevel worldserver1, String s1) {
+        // Paper end
         player.initInventoryMenu();
         // CraftBukkit - Moved from above, added world
         // Paper start - Add to collideRule team if needed
@@ -391,6 +408,7 @@ public abstract class PlayerList {
             scoreboard.addPlayerToTeam(player.getScoreboardName(), collideRuleTeam);
         }
         // Paper end
+        // CraftBukkit - Moved from above, added world
         PlayerList.LOGGER.info("{}[{}] logged in with entity id {} at ([{}]{}, {}, {})", player.getName().getString(), s1, player.getId(), worldserver1.serverLevelData.getLevelName(), player.getX(), player.getY(), player.getZ());
     }