IoC: Allow private scoped objects to resolve singleton services

Dalamud/Interface/Internal/Windows/Data/Widgets/ServicesWidget.cs

@@ -238,29 +238,42 @@ internal class ServicesWidget : IDataWindowWidget
             }
         }
 
-        if (ImGui.CollapsingHeader("Plugin-facing Services"))
+        if (ImGui.CollapsingHeader("Singleton Services"))
         {
             foreach (var instance in container.Instances)
             {
-                var hasInterface = container.InterfaceToTypeMap.Values.Any(x => x == instance.Key);
                 var isPublic = instance.Key.IsPublic;
 
                 ImGui.BulletText($"{instance.Key.FullName} ({instance.Key.GetServiceKind()})");
 
-                using (ImRaii.PushColor(ImGuiCol.Text, ImGuiColors.DalamudRed, !hasInterface))
-                {
-                    ImGui.Text(
-                        hasInterface
-                            ? $"\t => Provided via interface: {container.InterfaceToTypeMap.First(x => x.Value == instance.Key).Key.FullName}"
-                            : "\t => NO INTERFACE!!!");
-                }
-
                 if (isPublic)
                 {
                     using var color = ImRaii.PushColor(ImGuiCol.Text, ImGuiColors.DalamudRed);
                     ImGui.Text("\t => PUBLIC!!!");
                 }
 
+                switch (instance.Value.Visibility)
+                {
+                    case ObjectInstanceVisibility.Internal:
+                        ImGui.Text("\t => Internally resolved");
+                        break;
+
+                    case ObjectInstanceVisibility.ExposedToPlugins:
+                        var hasInterface = container.InterfaceToTypeMap.Values.Any(x => x == instance.Key);
+                        using (ImRaii.PushColor(ImGuiCol.Text, ImGuiColors.DalamudRed, !hasInterface))
+                        {
+                            ImGui.Text("\t => Exposed to plugins!");
+                            ImGui.Text(
+                                hasInterface
+                                    ? $"\t => Provided via interface: {container.InterfaceToTypeMap.First(x => x.Value == instance.Key).Key.FullName}"
+                                    : "\t => NO INTERFACE!!!");
+                        }
+
+                        break;
+                    default:
+                        throw new ArgumentOutOfRangeException();
+                }
+
                 ImGuiHelpers.ScaledDummy(2);
             }
         }

Dalamud/IoC/Internal/ObjectInstance.cs

@@ -13,9 +13,11 @@ internal class ObjectInstance
     /// </summary>
     /// <param name="instanceTask">Weak reference to the underlying instance.</param>
     /// <param name="type">Type of the underlying instance.</param>
-    public ObjectInstance(Task<WeakReference> instanceTask, Type type)
+    /// <param name="visibility">The visibility of this instance.</param>
+    public ObjectInstance(Task<WeakReference> instanceTask, Type type, ObjectInstanceVisibility visibility)
     {
         this.InstanceTask = instanceTask;
+        this.Visibility = visibility;
     }
 
     /// <summary>
@@ -23,4 +25,9 @@ internal class ObjectInstance
     /// </summary>
     /// <returns>The underlying instance.</returns>
     public Task<WeakReference> InstanceTask { get; }
+
+    /// <summary>
+    /// Gets or sets the visibility of the object instance.
+    /// </summary>
+    public ObjectInstanceVisibility Visibility { get; set; }
 }

Dalamud/IoC/Internal/ObjectInstanceVisibility.cs

@@ -0,0 +1,17 @@
+namespace Dalamud.IoC.Internal;
+
+/// <summary>
+/// Enum that declares the visibility of an object instance in the service container.
+/// </summary>
+internal enum ObjectInstanceVisibility
+{
+    /// <summary>
+    /// The object instance is only visible to other internal services.
+    /// </summary>
+    Internal,
+
+    /// <summary>
+    /// The object instance is visible to all services and plugins.
+    /// </summary>
+    ExposedToPlugins,
+}

Dalamud/IoC/Internal/ServiceContainer.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.ComponentModel.Design;
 using System.Diagnostics;
 using System.Linq;
 using System.Reflection;
@@ -29,6 +30,11 @@ internal class ServiceContainer : IServiceProvider, IServiceType
     /// </summary>
     public ServiceContainer()
     {
+        // Register the service container itself as a singleton.
+        // For all other services, this is done through the static constructor of Service{T}.
+        this.instances.Add(
+            typeof(IServiceContainer),
+            new(new Task<WeakReference>(() => new WeakReference(this), TaskCreationOptions.RunContinuationsAsynchronously), typeof(ServiceContainer), ObjectInstanceVisibility.Internal));
     }
 
     /// <summary>
@@ -45,15 +51,13 @@ internal class ServiceContainer : IServiceProvider, IServiceType
     /// Register a singleton object of any type into the current IOC container.
     /// </summary>
     /// <param name="instance">The existing instance to register in the container.</param>
+    /// <param name="visibility">The visibility of this singleton.</param>
     /// <typeparam name="T">The type to register.</typeparam>
-    public void RegisterSingleton<T>(Task<T> instance)
+    public void RegisterSingleton<T>(Task<T> instance, ObjectInstanceVisibility visibility)
     {
-        if (instance == null)
+        ArgumentNullException.ThrowIfNull(instance);
-        {
-            throw new ArgumentNullException(nameof(instance));
-        }
 
-        this.instances[typeof(T)] = new(instance.ContinueWith(x => new WeakReference(x.Result)), typeof(T));
+        this.instances[typeof(T)] = new(instance.ContinueWith(x => new WeakReference(x.Result)), typeof(T), visibility);
     }
 
     /// <summary>
@@ -81,10 +85,11 @@ internal class ServiceContainer : IServiceProvider, IServiceType
     /// Create an object.
     /// </summary>
     /// <param name="objectType">The type of object to create.</param>
+    /// <param name="allowedVisibility">Defines which services are allowed to be directly resolved into this type.</param>
     /// <param name="scopedObjects">Scoped objects to be included in the constructor.</param>
     /// <param name="scope">The scope to be used to create scoped services.</param>
     /// <returns>The created object.</returns>
-    public async Task<object> CreateAsync(Type objectType, object[] scopedObjects, IServiceScope? scope = null)
+    public async Task<object> CreateAsync(Type objectType, ObjectInstanceVisibility allowedVisibility, object[] scopedObjects, IServiceScope? scope = null)
     {
         var errorStep = "constructor lookup";
 
@@ -211,7 +216,7 @@ internal class ServiceContainer : IServiceProvider, IServiceType
     private ConstructorInfo? FindApplicableCtor(Type type, object[] scopedObjects)
     {
         // get a list of all the available types: scoped and singleton
-        var types = scopedObjects
+        var allValidServiceTypes = scopedObjects
                     .Select(o => o.GetType())
                     .Union(this.instances.Keys)
                     .ToArray();
@@ -224,7 +229,7 @@ internal class ServiceContainer : IServiceProvider, IServiceType
         var ctors = type.GetConstructors(ctorFlags);
         foreach (var ctor in ctors)
         {
-            if (this.ValidateCtor(ctor, types))
+            if (this.ValidateCtor(ctor, allValidServiceTypes))
             {
                 return ctor;
             }
@@ -233,11 +238,11 @@ internal class ServiceContainer : IServiceProvider, IServiceType
         return null;
     }
 
-    private bool ValidateCtor(ConstructorInfo ctor, Type[] types)
+    private bool ValidateCtor(ConstructorInfo ctor, Type[] validTypes)
     {
         bool IsTypeValid(Type type)
         {
-            var contains = types.Any(x => x.IsAssignableTo(type));
+            var contains = validTypes.Any(x => x.IsAssignableTo(type));
 
             // Scoped services are created on-demand
             return contains || type.GetCustomAttribute<ServiceManager.ScopedServiceAttribute>() != null;
@@ -254,7 +259,9 @@ internal class ServiceContainer : IServiceProvider, IServiceType
 
             if (!valid)
             {
-                Log.Error("Failed to validate {TypeName}, unable to find any services that satisfy the type", parameter.ParameterType.FullName!);
+                Log.Error("Ctor from {DeclaringType}: Failed to validate {TypeName}, unable to find any services that satisfy the type",
+                          ctor.DeclaringType?.FullName ?? ctor.DeclaringType?.Name ?? "null",
+                          parameter.ParameterType.FullName!);
                 return false;
             }
         }

Dalamud/IoC/Internal/ServiceScope.cs

@@ -25,9 +25,10 @@ internal interface IServiceScope : IAsyncDisposable
     /// Create an object.
     /// </summary>
     /// <param name="objectType">The type of object to create.</param>
+    /// <param name="allowedVisibility">Defines which services are allowed to be directly resolved into this type.</param>
     /// <param name="scopedObjects">Scoped objects to be included in the constructor.</param>
     /// <returns>The created object.</returns>
-    Task<object> CreateAsync(Type objectType, params object[] scopedObjects);
+    Task<object> CreateAsync(Type objectType, ObjectInstanceVisibility allowedVisibility, params object[] scopedObjects);
 
     /// <summary>
     /// Inject <see cref="PluginInterfaceAttribute" /> interfaces into public or static properties on the provided object.
@@ -72,13 +73,13 @@ internal class ServiceScopeImpl : IServiceScope
     }
 
     /// <inheritdoc />
-    public Task<object> CreateAsync(Type objectType, params object[] scopedObjects)
+    public Task<object> CreateAsync(Type objectType, ObjectInstanceVisibility allowedVisibility, params object[] scopedObjects)
     {
         this.disposeLock.EnterReadLock();
         try
         {
             ObjectDisposedException.ThrowIf(this.disposed, this);
-            return this.container.CreateAsync(objectType, scopedObjects, this);
+            return this.container.CreateAsync(objectType, allowedVisibility, scopedObjects, this);
         }
         finally
         {
@@ -117,7 +118,9 @@ internal class ServiceScopeImpl : IServiceScope
                 objectType,
                 static (objectType, p) => p.Scope.container.CreateAsync(
                     objectType,
-                    p.Objects.Concat(p.Scope.privateScopedObjects).ToArray()),
+                    ObjectInstanceVisibility.Internal, // We are allowed to resolve internal services here since this is a private scoped object.
+                    p.Objects.Concat(p.Scope.privateScopedObjects).ToArray(),
+                    p.Scope),
                 (Scope: this, Objects: scopedObjects));
         }
         finally

Dalamud/Plugin/DalamudPluginInterface.cs

@@ -19,6 +19,7 @@ using Dalamud.Interface;
 using Dalamud.Interface.Internal;
 using Dalamud.Interface.Internal.Windows.PluginInstaller;
 using Dalamud.Interface.Internal.Windows.Settings;
+using Dalamud.IoC.Internal;
 using Dalamud.Plugin.Internal;
 using Dalamud.Plugin.Internal.AutoUpdate;
 using Dalamud.Plugin.Internal.Types;
@@ -482,7 +483,7 @@ internal sealed class DalamudPluginInterface : IDalamudPluginInterface, IDisposa
 
     /// <inheritdoc/>
     public async Task<T> CreateAsync<T>(params object[] scopedObjects) where T : class =>
-        (T)await this.plugin.ServiceScope!.CreateAsync(typeof(T), this.GetPublicIocScopes(scopedObjects));
+        (T)await this.plugin.ServiceScope!.CreateAsync(typeof(T), ObjectInstanceVisibility.ExposedToPlugins, this.GetPublicIocScopes(scopedObjects));
 
     /// <inheritdoc/>
     public bool Inject(object instance, params object[] scopedObjects)

Dalamud/Plugin/Internal/Types/LocalPlugin.cs

@@ -577,7 +577,7 @@ internal class LocalPlugin : IAsyncDisposable
         var newInstanceTask = forceFrameworkThread ? framework.RunOnFrameworkThread(Create) : Create();
         return await newInstanceTask.ConfigureAwait(false);
 
-        async Task<IDalamudPlugin> Create() => (IDalamudPlugin)await scope.CreateAsync(type, dalamudInterface);
+        async Task<IDalamudPlugin> Create() => (IDalamudPlugin)await scope.CreateAsync(type, ObjectInstanceVisibility.ExposedToPlugins, dalamudInterface);
     }
 
     private static void SetupLoaderConfig(LoaderConfig config)

Dalamud/Service/ServiceManager.cs

@@ -139,10 +139,13 @@ internal static class ServiceManager
 #if DEBUG
         lock (LoadedServices)
         {
+            // ServiceContainer MUST be first. The static ctor of Service<T> will call Service<ServiceContainer>.Get()
+            // which causes a deadlock otherwise.
+            ProvideService(new ServiceContainer());
+
             ProvideService(dalamud);
             ProvideService(fs);
             ProvideService(configuration);
-            ProvideService(new ServiceContainer());
             ProvideService(scanner);
             ProvideService(localization);
         }

Dalamud/Service/Service{T}.cs

@@ -42,8 +42,13 @@ internal static class Service<T> where T : IServiceType
         else
             ServiceManager.Log.Debug("Service<{0}>: Static ctor called", type.Name);
 
-        if (exposeToPlugins)
+        // We can't use the service container to register itself. It does so in its constructor.
-            Service<ServiceContainer>.Get().RegisterSingleton(instanceTcs.Task);
+        if (typeof(T) != typeof(ServiceContainer))
+        {
+            Service<ServiceContainer>.Get().RegisterSingleton(
+                instanceTcs.Task,
+                exposeToPlugins ? ObjectInstanceVisibility.ExposedToPlugins : ObjectInstanceVisibility.Internal);
+        }
     }
 
     /// <summary>