Implement hard links in datastore for storing duplicate files

[morgs]

In #6729, skierpage commented:

I noticed that every time I start Browse, visit OLPC Library > images > world maps and click Africa (a PDF), another full copy of the PDF is added to ~olpc/.sugar/default/datastore/store by Read activity 45. If I read this bug correctly, that behavior is a downside of this bug fix.

This could be improved by hard linking identical files with copy-on-write to break the links.

[morgs]

See http://sugarlabs.org/go/DevelopmentTeam/0.84/Next_generation_journal

[skierpage]

Replying to morgs:

See http://sugarlabs.org/go/DevelopmentTeam/0.84/Next_generation_journal

That link is gone, see http://www.sugarlabs.org/go/DevelopmentTeam/0.84/Ideas#Journal instead (and there are other Journal ideas).

[cscott]

This bug has been added as an 8.2.1 blocker; next gen journal ideas are out. Is there a reasonable patch to our current 8.2 journal that does this?

[marco]

I think adding this feature to the current datastore is going to be too risky stability wise. Tomeu rewrite has it, but integrating it would mean to also ship a reimplementation of the usb sticks UI too.

Sayamindu has a patch to browse to open pdf inline, which would work around that case. That's by far the less risky approach, is it enough?

[mchua]

consensus from 8.2.1 meeting: push this ticket (general case) to a later release, unmadindu to make a new ticket with his patch for this specific case which will be in 8.2.1.

[cjb]

Pushing out of the 8.2.1 component.