From bfbd9adb82cb12c0f1243210ea3be0b81521e0bf Mon Sep 17 00:00:00 2001
From: Robert Paciorek <robert@opcode.eu.org>
Date: Fri, 1 Mar 2024 02:34:43 +0000
Subject: [PATCH] RespondJoinRoom in AddClient as atomic operation

to avoid missed player in rooms due to joining race condition
---
 src/CommandHandlers/SetUserVariablesHandler.cs | 2 +-
 src/Core/Client.cs                             | 2 +-
 src/Core/Room.cs                               | 5 ++++-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/CommandHandlers/SetUserVariablesHandler.cs b/src/CommandHandlers/SetUserVariablesHandler.cs
index 343fd4e..b21c15e 100644
--- a/src/CommandHandlers/SetUserVariablesHandler.cs
+++ b/src/CommandHandlers/SetUserVariablesHandler.cs
@@ -47,7 +47,7 @@ class SetUserVariablesHandler : ICommandHandler {
         client.PlayerData.Fp = suvData.Get<string>("FP");
 
         Console.WriteLine($"SUV {client.Room.Name} IID: {client.ClientID}");
-        client.Room.AddClient(client);
+
         UpdatePlayersInRoom();
         SendSUVToPlayerInRoom();
     }
diff --git a/src/Core/Client.cs b/src/Core/Client.cs
index efb88fa..f4b36d7 100644
--- a/src/Core/Client.cs
+++ b/src/Core/Client.cs
@@ -63,7 +63,7 @@ public class Client {
         LeaveRoom();
         InvalidatePlayerData();
         Room = room;
-        Send(Room.RespondJoinRoom());
+        Room.AddClient(this);
         Send(Room.SubscribeRoom());
         UpdatePlayerUserVariables();
     }
diff --git a/src/Core/Room.cs b/src/Core/Room.cs
index b864e3d..0007adb 100644
--- a/src/Core/Room.cs
+++ b/src/Core/Room.cs
@@ -6,7 +6,7 @@ public class Room {
     static Dictionary<string, Room> rooms = new();
 
     List<Client> clients = new();
-    public object roomLock = new object();
+    protected object roomLock = new object();
 
     public int Id { get; private set; }
     public string Name { get; private set; }
@@ -38,6 +38,9 @@ public class Room {
 
     public void AddClient(Client client) {
         lock (roomLock) {
+            client.Send(RespondJoinRoom());
+            // NOTE: send RespondJoinRoom() and add client to clients as atomic operation
+            //       to make sure to client get full list of players in room
             clients.Add(client);
         }
     }