Sync crashes with "Failed to get thumbnail"

[TheZoq2]

This most likely originates from thumbnail generation having failed without nulling the db entry thumbnail field.

[TheZoq2]

It seems like thumbnails are never None since thumbnail generation happens after storing the thumbnail name.

A possible 2 phase solution to this might be:

Phase 1

If thumbnail fetch returns an error. Ignore the file and store it anyway

Phase 2

Option 1

Figure out a way update db entries once thumbnails have been generated. There are several options for this:

Separate thumbnail table

Make thumbnails a Maybe one-to- maybe one mapping in the database. Generate a thumbnail ID that gets passed to both the generator and database and add them separately.

Pros:

• Simple implementation
  Cons:
• Same problem might happen for files
• Requires schema change

Add db entries after all tasks are done

Instead of starting worker threads for doing long winded operations when adding files but adding files immediately, use a job system similar to the way sync progress is handled.

Pros:

• No schema change
• Solves potential data inconsistency
  Cons:
• Tricky rewrite
• Requires a UI for reporting results to user
• More indirection with annoying error handling