reintroduce multi-instance launching

Bloxstrap/Bootstrapper.cs

@@ -471,13 +471,39 @@ namespace Bloxstrap
             }
         }
 
+        private static void LaunchMultiInstanceWatcher()
+        {
+            const string LOG_IDENT = "Bootstrapper::LaunchMultiInstanceWatcher";
+
+            if (Utilities.DoesMutexExist("ROBLOX_singletonMutex"))
+            {
+                App.Logger.WriteLine(LOG_IDENT, "Roblox singleton mutex already exists");
+                return;
+            }
+
+            using EventWaitHandle initEventHandle = new EventWaitHandle(false, EventResetMode.AutoReset, "Bloxstrap-MultiInstanceWatcherInitialisationFinished");
+            Process.Start(Paths.Process, "-multiinstancewatcher");
+
+            bool initSuccess = initEventHandle.WaitOne(TimeSpan.FromSeconds(2));
+            if (initSuccess)
+                App.Logger.WriteLine(LOG_IDENT, "Initialisation finished signalled, continuing.");
+            else
+                App.Logger.WriteLine(LOG_IDENT, "Did not receive the initialisation finished signal, continuing.");
+        }
+
         private void StartRoblox()
         {
             const string LOG_IDENT = "Bootstrapper::StartRoblox";
 
             SetStatus(Strings.Bootstrapper_Status_Starting);
 
-            if (_launchMode == LaunchMode.Player && App.Settings.Prop.ForceRobloxLanguage)
+            if (_launchMode == LaunchMode.Player)
+            {
+                // this needs to be done before roblox launches
+                if (App.Settings.Prop.MultiInstanceLaunching)
+                    LaunchMultiInstanceWatcher();
+
+                if (App.Settings.Prop.ForceRobloxLanguage)
                 {
                     var match = Regex.Match(_launchCommandLine, "gameLocale:([a-z_]+)", RegexOptions.CultureInvariant);
 
@@ -487,6 +513,7 @@ namespace Bloxstrap
                             $"robloxLocale:{match.Groups[1].Value}",
                             StringComparison.OrdinalIgnoreCase);
                 }
+            }
 
             var startInfo = new ProcessStartInfo()
             {

Bloxstrap/LaunchHandler.cs

@@ -59,6 +59,11 @@ namespace Bloxstrap
                 App.Logger.WriteLine(LOG_IDENT, "Opening watcher");
                 LaunchWatcher();
             }
+            else if (App.LaunchSettings.MultiInstanceWatcherFlag.Active)
+            {
+                App.Logger.WriteLine(LOG_IDENT, "Opening multi-instance watcher");
+                LaunchMultiInstanceWatcher();
+            }
             else if (App.LaunchSettings.BackgroundUpdaterFlag.Active)
             {
                 App.Logger.WriteLine(LOG_IDENT, "Opening background updater");
@@ -223,7 +228,7 @@ namespace Bloxstrap
                 App.Terminate(ErrorCode.ERROR_FILE_NOT_FOUND);
             }
 
-            if (App.Settings.Prop.ConfirmLaunches && Mutex.TryOpenExisting("ROBLOX_singletonMutex", out var _))
+            if (App.Settings.Prop.ConfirmLaunches && Mutex.TryOpenExisting("ROBLOX_singletonMutex", out var _) && !App.Settings.Prop.MultiInstanceLaunching)
             {
                 // this currently doesn't work very well since it relies on checking the existence of the singleton mutex
                 // which often hangs around for a few seconds after the window closes
@@ -302,6 +307,28 @@ namespace Bloxstrap
             });
         }
 
+        public static void LaunchMultiInstanceWatcher()
+        {
+            const string LOG_IDENT = "LaunchHandler::LaunchMultiInstanceWatcher";
+
+            App.Logger.WriteLine(LOG_IDENT, "Starting multi-instance watcher");
+
+            Task.Run(MultiInstanceWatcher.Run).ContinueWith(t =>
+            {
+                App.Logger.WriteLine(LOG_IDENT, "Multi instance watcher task has finished");
+
+                if (t.IsFaulted)
+                {
+                    App.Logger.WriteLine(LOG_IDENT, "An exception occurred when running the multi-instance watcher");
+
+                    if (t.Exception is not null)
+                        App.FinalizeExceptionHandling(t.Exception);
+                }
+
+                App.Terminate();
+            });
+        }
+
         public static void LaunchBackgroundUpdater()
         {
             const string LOG_IDENT = "LaunchHandler::LaunchBackgroundUpdater";

Bloxstrap/LaunchSettings.cs

@@ -16,6 +16,8 @@ namespace Bloxstrap
 
         public LaunchFlag WatcherFlag               { get; } = new("watcher");
 
+        public LaunchFlag MultiInstanceWatcherFlag  { get; } = new("multiinstancewatcher");
+
         public LaunchFlag BackgroundUpdaterFlag     { get; } = new("backgroundupdater");
 
         public LaunchFlag QuietFlag                 { get; } = new("quiet");

Bloxstrap/Models/Persistable/Settings.cs

@@ -11,6 +11,7 @@ namespace Bloxstrap.Models.Persistable
         public string BootstrapperIconCustomLocation { get; set; } = "";
         public Theme Theme { get; set; } = Theme.Default;
         public bool CheckForUpdates { get; set; } = true;
+        public bool MultiInstanceLaunching { get; set; } = false;
         public bool ConfirmLaunches { get; set; } = false;
         public string Locale { get; set; } = "nil";
         public bool ForceRobloxLanguage { get; set; } = false;

Bloxstrap/MultiInstanceWatcher.cs

@@ -0,0 +1,68 @@
+namespace Bloxstrap
+{
+    internal static class MultiInstanceWatcher
+    {
+        private static int GetOpenProcessesCount()
+        {
+            const string LOG_IDENT = "MultiInstanceWatcher::GetOpenProcessesCount";
+
+            try
+            {
+                // prevent any possible race conditions by checking for bloxstrap processes too
+                int count = Process.GetProcesses().Count(x => x.ProcessName is "RobloxPlayerBeta" or "Bloxstrap");
+                count -= 1; // ignore the current process
+                return count;
+            }
+            catch (Exception ex)
+            {
+                // everything process related can error at any time
+                App.Logger.WriteException(LOG_IDENT, ex);
+                return -1;
+            }
+        }
+
+        private static void FireInitialisedEvent()
+        {
+            using EventWaitHandle initEventHandle = new EventWaitHandle(false, EventResetMode.AutoReset, "Bloxstrap-MultiInstanceWatcherInitialisationFinished");
+            initEventHandle.Set();
+        }
+
+        public static void Run()
+        {
+            const string LOG_IDENT = "MultiInstanceWatcher::Run";
+
+            // try to get the mutex
+            bool acquiredMutex;
+            using Mutex mutex = new Mutex(false, "ROBLOX_singletonMutex");
+            try
+            {
+                acquiredMutex = mutex.WaitOne(0);
+            }
+            catch (AbandonedMutexException)
+            {
+                acquiredMutex = true;
+            }
+
+            if (!acquiredMutex)
+            {
+                App.Logger.WriteLine(LOG_IDENT, "Client singleton mutex is already acquired");
+                FireInitialisedEvent();
+                return;
+            }
+
+            App.Logger.WriteLine(LOG_IDENT, "Acquired mutex!");
+            FireInitialisedEvent();
+
+            // watch for alive processes
+            int count;
+            do
+            {
+                Thread.Sleep(5000);
+                count = GetOpenProcessesCount();
+            }
+            while (count == -1 || count > 0); // redo if -1 (one of the Process apis failed)
+
+            App.Logger.WriteLine(LOG_IDENT, "All Roblox related processes have closed, exiting!");
+        }
+    }
+}

Bloxstrap/Resources/Strings.Designer.cs

@@ -3425,6 +3425,24 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Allows for having more than one Roblox game client instance open simultaneously..
+        /// </summary>
+        public static string Menu_Integrations_MultiInstanceLaunching_Description {
+            get {
+                return ResourceManager.GetString("Menu.Integrations.MultiInstanceLaunching.Description", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Allow multi-instance launching.
+        /// </summary>
+        public static string Menu_Integrations_MultiInstanceLaunching_Title {
+            get {
+                return ResourceManager.GetString("Menu.Integrations.MultiInstanceLaunching.Title", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to When in-game, you&apos;ll be able to see where your server is located via [ipinfo.io]({0})..
         /// </summary>

Bloxstrap/Resources/Strings.resx

@@ -1487,4 +1487,10 @@ Defaulting to {1}.</value>
     <value>Custom Theme {0}</value>
     <comment>{0} is a string (e.g. '1', '1-1234')</comment>
   </data>
+  <data name="Menu.Integrations.MultiInstanceLaunching.Title" xml:space="preserve">
+    <value>Allow multi-instance launching</value>
+  </data>
+  <data name="Menu.Integrations.MultiInstanceLaunching.Description" xml:space="preserve">
+    <value>Allows for having more than one Roblox game client instance open simultaneously.</value>
+  </data>
 </root>

Bloxstrap/UI/Elements/Settings/Pages/IntegrationsPage.xaml

@@ -66,6 +66,14 @@
             <ui:ToggleSwitch IsChecked="{Binding DiscordAccountOnProfile, Mode=TwoWay}" />
         </controls:OptionControl>
 
+        <TextBlock Text="{x:Static resources:Strings.Common_Miscellaneous}" FontSize="20" FontWeight="Medium" Margin="0,16,0,0" />
+
+        <controls:OptionControl 
+            Header="{x:Static resources:Strings.Menu_Integrations_MultiInstanceLaunching_Title}" 
+            Description="{x:Static resources:Strings.Menu_Integrations_MultiInstanceLaunching_Description}">
+            <ui:ToggleSwitch IsChecked="{Binding MultiInstanceLaunchingEnabled, Mode=TwoWay}" />
+        </controls:OptionControl>
+
         <TextBlock Text="{x:Static resources:Strings.Menu_Integrations_Custom_Title}" FontSize="20" FontWeight="Medium" Margin="0,16,0,0" />
         <TextBlock Text="{x:Static resources:Strings.Menu_Integrations_Custom_Description}" TextWrapping="Wrap" Foreground="{DynamicResource TextFillColorSecondaryBrush}" />
         <Grid Margin="0,8,0,0">

Bloxstrap/UI/ViewModels/Settings/IntegrationsViewModel.cs

@@ -125,6 +125,12 @@ namespace Bloxstrap.UI.ViewModels.Settings
             set => App.Settings.Prop.UseDisableAppPatch = value;
         }
 
+        public bool MultiInstanceLaunchingEnabled
+        {
+            get => App.Settings.Prop.MultiInstanceLaunching;
+            set => App.Settings.Prop.MultiInstanceLaunching = value;
+        }
+
         public ObservableCollection<CustomIntegration> CustomIntegrations
         {
             get => App.Settings.Prop.CustomIntegrations;