Bug 453135

Summary:	Implement the Shared Thumbnail repositories part of the Thumbnail Managing Standard
Product:	[Frameworks and Libraries] kio-extras	Reporter:	zirrit <sjctvjkrtazfmcugjt>
Component:	Thumbnails and previews	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	CONFIRMED ---
Severity:	wishlist	CC:	kde
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Other
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description zirrit 2022-04-28 12:31:02 UTC

SUMMARY
Say you are a network admin and you have multiple KDE/Dolphin users working with network directories containing images/videos and multiple people try to access a directory which they have not accessed before. For each of the users their respective Dolphin/KIO instance will scrape the directory and generate user-local previews. This pounds the network server to a halt due to the preview generation I/O.

Right now Dolphin has 2 operational modes based on user preferences neither of which help because users have to interact with the images:
1. Don't create previews at all
2. Create previews below a certain size

As per Thumbnail Managing Standard it is possible to crate a hidden .sh_thumbnails directory which will contain the thumbnails for the directory.

Would it be possible for Dolphin/KIO/KDE to implement the .sh_thumbnails part of the Thumbnail Managing Standard?

STEPS TO REPRODUCE
1. Have remote location previews generation enabled
2. Delete local thumbnail directory
3. Visit a network location with a lot of image/video files

OBSERVED RESULT
Dolphin/KIO recreates the thumbnails for the files located in the network dir.
Thumbnails are created in the local thumbnail directory.
Thumbnail creation is slow for a large number of files because it is single threaded.

EXPECTED RESULT
Dolphin/KIO should offer the user the option to create the .sh_thumbnails directory in the network location or it should automatically create such a directory if the user enables such an option.

ADDITIONAL INFORMATION
https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html#SHARED

Comment 1 David Edmundson 2022-04-28 13:11:29 UTC

>or it should automatically create such a directory if the user enables such an option.

That's not what the spec says:

"This is a read-only collection of thumbnails"

We can still implement the spec if we don't already, but to solve your use case you'll need some server side daemon populating it.

Comment 2 David Edmundson 2022-04-28 13:20:16 UTC

I can confirm we do not implement it currently.