Previews for single shared files is not updated

[MorrisJobke]

• upload a file abc.png
• share this file
• overwrite the file abc.png with another image via WebDAV
• check the shared link

expected

• preview is updated

actual

• preview is not updated

[MorrisJobke]

This is only stable9

[rullzer]

The issue is non-shared previews:

• Share a folder with a group
• Upload a file a.png to that folder as owner
• As recipient overwrite a.png
• See that the owners preview is not updated

[rullzer]

As discussed in person last week. This boils down to the shared preview issue.

In the current state all previews are bound to the user. Which means that if N people have access to a file N previews will be generated (well N*M since you can have multiple preview sizes). We have no (scaleable) way to clean this up properly.

The solution is we should share previews. This saves time (generation) and space (deduplication) of previews. I'm working on a PR to make this happen.

[adsworth]

I just ran into this as well. There is also no way of fixing this. The owner either has to touch the images so they are resynced and his previews get regenerated or the admin has to delete the users thumbnails directory.

[rullzer]

Fixed with #1741