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Re: [PATCH v2 04/12] refs: implement simple transactions for the packed-refs file

From
Jeff King <peff@peff.net>
Date
Jun 20, 2013, 19:55 UTC
Message-ID
<20130620195526.GA31364@sigill.intra.peff.net>
In-Reply-To
<51C343FF.6030002@alum.mit.edu>
On Thu, Jun 20, 2013 at 08:03:43PM +0200, Michael Haggerty wrote:
Show 14 quoted lines
> > I noticed that recently, too. I have a patch series about 90% complete
> > that abstracts the tempfile handling (the ultimate goal of which is to
> > optionally clean up tmp_* files in the objects/ directory). It refactors
> > the lockfile cleanup, and it would not be too hard to have a committed
> > or rolled-back lockfile actually remove itself from the "to clean at
> > exit" list.
> > 
> > Which would make it perfectly safe to have a lockfile as an automatic
> > variable as long as you commit or rollback before leaving the function.
> 
> Cool, then I won't work on that.  You might also have to make the
> lockfile list into a doubly-linked-list to avoid having to do a linear
> scan to find the entry to delete, unless the total number of entries is
> known to remain small.

Yes, I noticed that potential issue, but I don't think it is worth worrying about. We typically only take one lock at a time, or a handful of tempfiles (e.g., one object at a time, or two files for diff).

And once it's abstracted out, it would be easy to handle later.

The part I am a little stuck on is plugging it into pack-objects/index-pack. Their output handling is a little convoluted because they may be writing to stdout, to a tempfile, to a named file, or even appending to an existing file in the case of index-pack --fix-thin. I don't think it's unmanageable, but I need to spend some more time on the refactoring.

> Please CC me on the patch series when it is done.
Will do.
-Peff
Previous: Michael HaggertyNext: Junio C Hamano
Message 10 of 24 in “Fix some reference-related races”
  1. 00/12 Fix some reference-related racesMichael Haggerty, Jun 19, 2013
  2. 01/12 repack_without_ref(): split list curation and entry writingMichael Haggerty, Jun 19, 2013
  3. 02/12 pack_refs(): split creation of packed refs and entry writingMichael Haggerty, Jun 19, 2013
  4. 03/12 refs: wrap the packed refs cache in a level of indirectionMichael Haggerty, Jun 19, 2013
  5. 04/12 refs: implement simple transactions for the packed-refs fileMichael Haggerty, Jun 19, 2013
  6. Junio C HamanoJun 19, 2013
  7. Michael HaggertyJun 20, 2013
  8. Jeff KingJun 20, 2013
  9. Michael HaggertyJun 20, 2013
  10. Jeff KingJun 20, 2013
  11. Junio C HamanoJun 20, 2013
  12. Michael HaggertyJun 20, 2013
  13. Junio C HamanoJun 20, 2013
  14. 05/12 refs: manage lifetime of packed refs cache via reference countingMichael Haggerty, Jun 19, 2013
  15. 06/12 do_for_each_entry(): increment the packed refs cache refcountMichael Haggerty, Jun 19, 2013
  16. 07/12 packed_ref_cache: increment refcount when lockedMichael Haggerty, Jun 19, 2013
  17. 08/12 Extract a struct stat_data from cache_entryMichael Haggerty, Jun 19, 2013
  18. 09/12 add a stat_validity structMichael Haggerty, Jun 19, 2013
  19. 10/12 get_packed_ref_cache: reload packed-refs file when it changesMichael Haggerty, Jun 19, 2013
  20. 11/12 for_each_ref: load all loose refs before packed refsMichael Haggerty, Jun 19, 2013
  21. 12/12 refs: do not invalidate the packed-refs cache unnecessarilyMichael Haggerty, Jun 19, 2013
  22. Jeff KingJun 19, 2013
  23. Michael HaggertyJun 20, 2013
  24. Jeff KingJun 20, 2013

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