Fix removing large amount of assets in Editor at once

#1484

Source/Editor/Modules/ContentDatabaseModule.cs

@@ -649,8 +649,6 @@ namespace FlaxEditor.Modules
             // Special case for folders
             if (item is ContentFolder folder)
             {
-                // TODO: maybe don't remove folders recursive but at once?
-
                 // Delete all children
                 if (folder.Children.Count > 0)
                 {
@@ -664,6 +662,9 @@ namespace FlaxEditor.Modules
                 // Remove directory
                 if (deletedByUser && Directory.Exists(path))
                 {
+                    // Flush files removal before removing folder (loaded assets remove file during object destruction in Asset::OnDeleteObject)
+                    FlaxEngine.Scripting.FlushRemovedObjects();
+
                     try
                     {
                         Directory.Delete(path, true);

Source/Editor/Windows/ContentWindow.cs

@@ -629,8 +629,9 @@ namespace FlaxEditor.Windows
             if (items.Count == 0)
                 return;
 
-            // TODO: remove items that depend on different items in the list: use wants to remove `folderA` and `folderA/asset.x`, we should just remove `folderA`
+            // Sort items to remove files first, then folders
             var toDelete = new List<ContentItem>(items);
+            toDelete.Sort((a, b) => a.IsFolder ? 1 : -1);
 
             string msg = toDelete.Count == 1
                          ? string.Format("Are you sure to delete \'{0}\'?\nThis action cannot be undone. Files will be deleted permanently.", items[0].Path)

Source/Engine/Content/Content.cpp

@@ -521,37 +521,33 @@ Asset* Content::GetAsset(const Guid& id)
 
 void Content::DeleteAsset(Asset* asset)
 {
-    ScopeLock locker(AssetsLocker);
-
-    // Validate
     if (asset == nullptr || asset->_deleteFileOnUnload)
-    {
-        // Back
         return;
-    }
 
     LOG(Info, "Deleting asset {0}...", asset->ToString());
 
+    // Ensure that asset is loaded (easier than cancel in-flight loading)
+    asset->WaitForLoaded();
+
     // Mark asset for delete queue (delete it after auto unload)
     asset->_deleteFileOnUnload = true;
 
     // Unload
-    UnloadAsset(asset);
+    asset->DeleteObject();
 }
 
 void Content::DeleteAsset(const StringView& path)
 {
-    ScopeLock locker(AssetsLocker);
-
-    // Check if is loaded
+    // Try to delete already loaded asset
     Asset* asset = GetAsset(path);
     if (asset != nullptr)
     {
-        // Delete asset
         DeleteAsset(asset);
         return;
     }
 
+    ScopeLock locker(AssetsLocker);
+
     // Remove from registry
     AssetInfo info;
     if (Cache.DeleteAsset(path, &info))
@@ -573,7 +569,6 @@ void Content::deleteFileSafety(const StringView& path, const Guid& id)
     // Check if given id is invalid
     if (!id.IsValid())
     {
-        // Cancel operation
         LOG(Warning, "Cannot remove file \'{0}\'. Given ID is invalid.", path);
         return;
     }
@@ -585,7 +580,6 @@ void Content::deleteFileSafety(const StringView& path, const Guid& id)
         storage->CloseFileHandles(); // Close file handle to allow removing it
         if (!storage->HasAsset(id))
         {
-            // Skip removing
             LOG(Warning, "Cannot remove file \'{0}\'. It doesn\'t contain asset {1}.", path, id);
             return;
         }
@@ -790,10 +784,8 @@ bool Content::CloneAssetFile(const StringView& dstPath, const StringView& srcPat
 
 void Content::UnloadAsset(Asset* asset)
 {
-    // Check input
     if (asset == nullptr)
         return;
-
     asset->DeleteObject();
 }