From 617ff40de763228ed652828d67a14cf462a7e000 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Mon, 2 Aug 2021 14:44:51 +0900
Subject: [PATCH] Add the ability to not use MessagePack when creating a
 `HubConnector`

---
 osu.Game/Online/API/APIAccess.cs                       | 4 ++--
 osu.Game/Online/API/DummyAPIAccess.cs                  | 2 +-
 osu.Game/Online/API/IAPIProvider.cs                    | 3 ++-
 osu.Game/Online/HubClientConnector.cs                  | 7 +++++--
 osu.Game/Online/Multiplayer/OnlineMultiplayerClient.cs | 4 +++-
 5 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/osu.Game/Online/API/APIAccess.cs b/osu.Game/Online/API/APIAccess.cs
index b35dfa11cb..f7a3f4602f 100644
--- a/osu.Game/Online/API/APIAccess.cs
+++ b/osu.Game/Online/API/APIAccess.cs
@@ -257,8 +257,8 @@ namespace osu.Game.Online.API
             this.password = password;
         }
 
-        public IHubClientConnector GetHubConnector(string clientName, string endpoint) =>
-            new HubClientConnector(clientName, endpoint, this, versionHash);
+        public IHubClientConnector GetHubConnector(string clientName, string endpoint, bool preferMessagePack) =>
+            new HubClientConnector(clientName, endpoint, this, versionHash, preferMessagePack);
 
         public RegistrationRequest.RegistrationRequestErrors CreateAccount(string email, string username, string password)
         {
diff --git a/osu.Game/Online/API/DummyAPIAccess.cs b/osu.Game/Online/API/DummyAPIAccess.cs
index 52f2365165..1ba31db9fa 100644
--- a/osu.Game/Online/API/DummyAPIAccess.cs
+++ b/osu.Game/Online/API/DummyAPIAccess.cs
@@ -89,7 +89,7 @@ namespace osu.Game.Online.API
             state.Value = APIState.Offline;
         }
 
-        public IHubClientConnector GetHubConnector(string clientName, string endpoint) => null;
+        public IHubClientConnector GetHubConnector(string clientName, string endpoint, bool preferMessagePack) => null;
 
         public RegistrationRequest.RegistrationRequestErrors CreateAccount(string email, string username, string password)
         {
diff --git a/osu.Game/Online/API/IAPIProvider.cs b/osu.Game/Online/API/IAPIProvider.cs
index 3a77b9cfee..686df5c57c 100644
--- a/osu.Game/Online/API/IAPIProvider.cs
+++ b/osu.Game/Online/API/IAPIProvider.cs
@@ -102,7 +102,8 @@ namespace osu.Game.Online.API
         /// </summary>
         /// <param name="clientName">The name of the client this connector connects for, used for logging.</param>
         /// <param name="endpoint">The endpoint to the hub.</param>
-        IHubClientConnector? GetHubConnector(string clientName, string endpoint);
+        /// <param name="preferMessagePack"></param>
+        IHubClientConnector? GetHubConnector(string clientName, string endpoint, bool preferMessagePack = true);
 
         /// <summary>
         /// Create a new user account. This is a blocking operation.
diff --git a/osu.Game/Online/HubClientConnector.cs b/osu.Game/Online/HubClientConnector.cs
index 3876c8bbe6..6c6a217f54 100644
--- a/osu.Game/Online/HubClientConnector.cs
+++ b/osu.Game/Online/HubClientConnector.cs
@@ -26,6 +26,7 @@ namespace osu.Game.Online
         private readonly string clientName;
         private readonly string endpoint;
         private readonly string versionHash;
+        private readonly bool preferMessagePack;
         private readonly IAPIProvider api;
 
         /// <summary>
@@ -51,12 +52,14 @@ namespace osu.Game.Online
         /// <param name="endpoint">The endpoint to the hub.</param>
         /// <param name="api"> An API provider used to react to connection state changes.</param>
         /// <param name="versionHash">The hash representing the current game version, used for verification purposes.</param>
-        public HubClientConnector(string clientName, string endpoint, IAPIProvider api, string versionHash)
+        /// <param name="preferMessagePack">Whether to use MessagePack for serialisation if available on this platform.</param>
+        public HubClientConnector(string clientName, string endpoint, IAPIProvider api, string versionHash, bool preferMessagePack = true)
         {
             this.clientName = clientName;
             this.endpoint = endpoint;
             this.api = api;
             this.versionHash = versionHash;
+            this.preferMessagePack = preferMessagePack;
 
             apiState.BindTo(api.State);
             apiState.BindValueChanged(state =>
@@ -144,7 +147,7 @@ namespace osu.Game.Online
                     options.Headers.Add("OsuVersionHash", versionHash);
                 });
 
-            if (RuntimeInfo.SupportsJIT)
+            if (RuntimeInfo.SupportsJIT && preferMessagePack)
                 builder.AddMessagePackProtocol();
             else
             {
diff --git a/osu.Game/Online/Multiplayer/OnlineMultiplayerClient.cs b/osu.Game/Online/Multiplayer/OnlineMultiplayerClient.cs
index 8137430d8e..1dfc60312b 100644
--- a/osu.Game/Online/Multiplayer/OnlineMultiplayerClient.cs
+++ b/osu.Game/Online/Multiplayer/OnlineMultiplayerClient.cs
@@ -37,7 +37,9 @@ namespace osu.Game.Online.Multiplayer
         [BackgroundDependencyLoader]
         private void load(IAPIProvider api)
         {
-            connector = api.GetHubConnector(nameof(OnlineMultiplayerClient), endpoint);
+            // Importantly, we are intentionally not using MessagePack here to correctly support derived class serialization.
+            // More information on the limitations / reasoning can be found in osu-server-spectator's initialisation code.
+            connector = api.GetHubConnector(nameof(OnlineMultiplayerClient), endpoint, false);
 
             if (connector != null)
             {