Fix deadlock in asset thumbnails rendering queue when texture streaming fails

#2057

Source/Editor/Content/Thumbnails/ThumbnailRequest.cs

@@ -35,6 +35,11 @@ namespace FlaxEditor.Content.Thumbnails
             /// The finalized state.
             /// </summary>
             Disposed,
+
+            /// <summary>
+            /// The request has failed (eg. asset cannot be loaded).
+            /// </summary>
+            Failed,
         };
 
         /// <summary>
@@ -78,6 +83,14 @@ namespace FlaxEditor.Content.Thumbnails
             Proxy = proxy;
         }
 
+        internal void Update()
+        {
+            if (State == States.Prepared && (!Asset || Asset.LastLoadFailed))
+            {
+                State = States.Failed;
+            }
+        }
+
         /// <summary>
         /// Prepares this request.
         /// </summary>
@@ -85,11 +98,8 @@ namespace FlaxEditor.Content.Thumbnails
         {
             if (State != States.Created)
                 throw new InvalidOperationException();
-
-            // Prepare
             Asset = FlaxEngine.Content.LoadAsync(Item.Path);
             Proxy.OnThumbnailDrawPrepare(this);
-
             State = States.Prepared;
         }
 
@@ -101,9 +111,7 @@ namespace FlaxEditor.Content.Thumbnails
         {
             if (State != States.Prepared)
                 throw new InvalidOperationException();
-
             Item.Thumbnail = icon;
-
             State = States.Rendered;
         }
 

Source/Editor/Content/Thumbnails/ThumbnailsModule.cs

@@ -120,6 +120,8 @@ namespace FlaxEditor.Content.Thumbnails
 
         internal static bool HasMinimumQuality(TextureBase asset)
         {
+            if (asset.HasStreamingError)
+                return true; // Don't block thumbnails queue when texture fails to stream in (eg. unsupported format)
             var mipLevels = asset.MipLevels;
             var minMipLevels = Mathf.Min(mipLevels, 7);
             return asset.IsLoaded && asset.ResidentMipLevels >= Mathf.Max(minMipLevels, (int)(mipLevels * MinimumRequiredResourcesQuality));
@@ -499,6 +501,7 @@ namespace FlaxEditor.Content.Thumbnails
                         var request = _requests[i];
                         try
                         {
+                            request.Update();
                             if (request.IsReady)
                             {
                                 isAnyReady = true;
@@ -507,6 +510,10 @@ namespace FlaxEditor.Content.Thumbnails
                             {
                                 request.Prepare();
                             }
+                            else if (request.State == ThumbnailRequest.States.Failed)
+                            {
+                                _requests.RemoveAt(i--);
+                            }
                         }
                         catch (Exception ex)
                         {