Remove unused delegate, use model name in notifications, add more xmldoc

- Applies a `class` constraint to the generic type in `IModelManager`
- Add xmldoc

osu.Game/Beatmaps/BeatmapManager.cs

@@ -55,8 +55,6 @@ namespace osu.Game.Beatmaps
 
         private readonly BeatmapStore beatmaps;
 
-        private readonly IAPIProvider api;
-
         private readonly AudioManager audioManager;
 
         private readonly GameHost host;
@@ -68,7 +66,6 @@ namespace osu.Game.Beatmaps
             : base(storage, contextFactory, api, new BeatmapStore(contextFactory), host)
         {
             this.rulesets = rulesets;
-            this.api = api;
             this.audioManager = audioManager;
             this.host = host;
 

osu.Game/Database/ArchiveModelManager.cs

@@ -35,8 +35,6 @@ namespace osu.Game.Database
         where TModel : class, IHasFiles<TFileModel>, IHasPrimaryKey, ISoftDelete
         where TFileModel : INamedFileInfo, new()
     {
-        public delegate void ItemAddedDelegate(TModel model, bool existing);
-
         /// <summary>
         /// Set an endpoint for notifications to be posted to.
         /// </summary>

osu.Game/Database/DownloadableArchiveModelManager.cs

@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using Humanizer;
 using osu.Framework.Logging;
 using osu.Framework.Platform;
 using osu.Game.Online.API;
@@ -112,8 +113,7 @@ namespace osu.Game.Database
                 if (error is OperationCanceledException) return;
 
                 notification.State = ProgressNotificationState.Cancelled;
-                // TODO: maybe implement a Name for every model that we can use in this message?
-                Logger.Error(error, "Download failed!");
+                Logger.Error(error, $"{HumanisedModelName.Titleize()} download failed!");
                 currentDownloads.Remove(request);
             };
 

osu.Game/Database/IModelDownloader.cs

@@ -6,6 +6,10 @@ using System;
 
 namespace osu.Game.Database
 {
+    /// <summary>
+    /// Represents a <see cref="IModelManager{TModel}"/> that can download new models from an external source.
+    /// </summary>
+    /// <typeparam name="TModel">The model type.</typeparam>
     public interface IModelDownloader<TModel> : IModelManager<TModel>
         where TModel : class
     {
@@ -23,7 +27,7 @@ namespace osu.Game.Database
 
         /// <summary>
         /// Downloads a <see cref="TModel"/>.
-        /// This will post notifications tracking progress.
+        /// This may post notifications tracking progress.
         /// </summary>
         /// <param name="model">The <see cref="TModel"/> to be downloaded.</param>
         /// <returns>Whether downloading can happen.</returns>
@@ -31,7 +35,7 @@ namespace osu.Game.Database
 
         /// <summary>
         /// Downloads a <see cref="TModel"/> with optional parameters for the download request.
-        /// This will post notifications tracking progress.
+        /// This may post notifications tracking progress.
         /// </summary>
         /// <param name="model">The <see cref="TModel"/> to be downloaded.</param>
         /// <param name="extra">Optional parameters to be used for creating the download request.</param>

osu.Game/Database/IModelManager.cs

@@ -5,7 +5,12 @@ using System;
 
 namespace osu.Game.Database
 {
+    /// <summary>
+    /// Represents a model manager that publishes events when <see cref="TModel"/>s are added or removed.
+    /// </summary>
+    /// <typeparam name="TModel">The model type.</typeparam>
     public interface IModelManager<TModel>
+        where TModel : class
     {
         event Action<TModel, bool> ItemAdded;