ioc: cancel all blocking Get()'s when unloading (#1772)

Dalamud/ServiceManager.cs

@@ -43,6 +43,7 @@ internal static class ServiceManager
 #endif
 
     private static readonly TaskCompletionSource BlockingServicesLoadedTaskCompletionSource = new();
+    private static readonly CancellationTokenSource UnloadCancellationTokenSource = new();
 
     private static ManualResetEvent unloadResetEvent = new(false);
 
@@ -108,6 +109,12 @@ internal static class ServiceManager
     /// </summary>
     public static Task BlockingResolved { get; } = BlockingServicesLoadedTaskCompletionSource.Task;
     
+    /// <summary>
+    /// Gets a cancellation token that will be cancelled once Dalamud needs to unload, be it due to a failure state
+    /// during initialization or during regular operation.
+    /// </summary>
+    public static CancellationToken UnloadCancellationToken => UnloadCancellationTokenSource.Token;
+
     /// <summary>
     /// Initializes Provided Services and FFXIVClientStructs.
     /// </summary>
@@ -374,6 +381,8 @@ internal static class ServiceManager
         }
         catch (Exception e)
         {
+            UnloadCancellationTokenSource.Cancel();
+
             Log.Error(e, "Failed resolving services");
             try
             {
@@ -401,6 +410,8 @@ internal static class ServiceManager
     /// </summary>
     public static void UnloadAllServices()
     {
+        UnloadCancellationTokenSource.Cancel();
+        
         var framework = Service<Framework>.GetNullable(Service<Framework>.ExceptionPropagationMode.None);
         if (framework is { IsInFrameworkUpdateThread: false, IsFrameworkUnloading: false })
         {

Dalamud/Service{T}.cs

@@ -116,7 +116,7 @@ internal static class Service<T> where T : IServiceType
 #endif
 
         if (!instanceTcs.Task.IsCompleted)
-            instanceTcs.Task.Wait();
+            instanceTcs.Task.Wait(ServiceManager.UnloadCancellationToken);
         return instanceTcs.Task.Result;
     }