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Re: [PATCH v2 28/51] refs.c: rename ref_array -> ref_dir

From
Jeff King <peff@peff.net>
Date
Feb 10, 2012, 20:44 UTC
Message-ID
<20120210204457.GD5504@sigill.intra.peff.net>
In-Reply-To
<4F352F03.2030104@alum.mit.edu>
On Fri, Feb 10, 2012 at 03:51:47PM +0100, Michael Haggerty wrote:
Show 14 quoted lines
> First problem: everything_local() seems to be either broken or used
> incorrectly.  I can't decide which because I don't know what its
> semantics are *supposed* to be.
> 
> If everything_local() is trying to check that the references are all in
> the local repository itself, then it is incorrect for clone to enter
> alternates into extra_refs because everything_local() then mistakes them
> for local.
> 
> If everything_local() is trying to check that the references are in the
> local repository plus alternates, then it is incorrect that
> everything_local() doesn't consider alternate references in its
> determination.  My guess is that this is the case, and that something
> like the following might be the fix:

Junio could answer more authoritatively than I, but I am pretty sure it is the latter. The point is to skip the expensive find_common negotiation if we know that there are no objects to fetch. Thus the "local" here is "do we have them on this side of the git-protocol connection", not "do we have them in our non-alternates repository".

Show 25 quoted lines
> > ----------------------------- builtin/fetch-pack.c -----------------------------
> > index 9500f35..4257a8d 100644
> > @@ -581,6 +581,11 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
> >  	*refs = newlist;
> >  }
> >  
> > +static void mark_alternate_complete(const struct ref *ref, void *unused)
> > +{
> > +	mark_complete(NULL, ref->old_sha1, 0, NULL);
> > +}
> > +
> >  static int everything_local(struct ref **refs, int nr_match, char **match)
> >  {
> >  	struct ref *ref;
> > @@ -609,6 +614,7 @@ static int everything_local(struct ref **refs, int nr_match, char **match)
> >  
> >  	if (!args.depth) {
> >  		for_each_ref(mark_complete, NULL);
> > +		for_each_alternate_ref(mark_alternate_complete, NULL);
> >  		if (cutoff)
> >  			mark_recent_complete_commits(cutoff);
> >  	}
> 
> With this patch, then the full test suite passes even if I take out the
> code that adds the alternate refs to extra_refs.
That looks sane to me.
Show 10 quoted lines
> Specifically: (without the above patch) I commented out the call to
> add_extra_ref() in clone.c:add_one_reference(), then ran t5700 through
> step 8 then aborted.  insert_one_alternate_ref() was called four times:
> 
> insert_one_alternate_ref(ccc25a1f9655742174c93f48f616bea8ad0bc6ff)
> insert_one_alternate_ref(ccc25a1f9655742174c93f48f616bea8ad0bc6ff)
> insert_one_alternate_ref(5355551c5a927a2b6349505ada2da4bb702c0a49)
> insert_one_alternate_ref(5355551c5a927a2b6349505ada2da4bb702c0a49)
> 
> (The duplication here seems strange.)

I think the duplication can be explained. The alternate-refs mechanism gets the list of refs by running "git ls-remote" on each alternate. The symbolic refs appear as refs in that list. So in t5700, for example, I get:

  $ git ls-remote B
  56a2e291e54b1a92180fe2072152e6aa0919fc5f        HEAD
  56a2e291e54b1a92180fe2072152e6aa0919fc5f        refs/heads/master
  3ee812e8486c2474e2b03be5c0b42e33092da069        refs/remotes/origin/HEAD
  3ee812e8486c2474e2b03be5c0b42e33092da069        refs/remotes/origin/master

Because you don't actually care about the alternate refs themselves, but only about their sha1 values, you could eliminate duplicates early. The code in receive-pack already does this; fetch-pack should probably do the same (it's not _wrong_ not to, but in some pathological cases, the duplicates can make performance worse).

Show 16 quoted lines
> want 5355551c5a927a2b6349505ada2da4bb702c0a49 multi_ack_detailed
> side-band-64k thin-pack ofs-delta
> want 5355551c5a927a2b6349505ada2da4bb702c0a49
> #E
> 
> The "5355551c" object corresponds to refs/remotes/origin/master in the
> alternate object store:
> 
> $ (cd B; git for-each-ref)
> ccc25a1f9655742174c93f48f616bea8ad0bc6ff commit	refs/heads/master
> 5355551c5a927a2b6349505ada2da4bb702c0a49 commit	refs/remotes/origin/HEAD
> 5355551c5a927a2b6349505ada2da4bb702c0a49 commit	refs/remotes/origin/master
> 
> It seems to me that even in the absence of short-circuiting due to
> everything_local() returning true, the presence of the alternate refs
> should be suppressing the "want" lines for those references.
Yeah, that definitely seems like a bug in find_common.
-Peff
Previous: Michael HaggertyNext: Junio C Hamano
Message 52 of 79 in “ref-api-C and ref-api-D re-roll”
  1. 00/51 ref-api-C and ref-api-D re-rollmhagger@alum.mit.edu, Dec 12, 2011
  2. 01/51 struct ref_entry: document name membermhagger@alum.mit.edu, Dec 12, 2011
  3. 02/51 refs: rename "refname" variablesmhagger@alum.mit.edu, Dec 12, 2011
  4. Junio C HamanoDec 13, 2011
  5. 03/51 refs: rename parameters result -> sha1mhagger@alum.mit.edu, Dec 12, 2011
  6. 04/51 clear_ref_array(): rename from free_ref_array()mhagger@alum.mit.edu, Dec 12, 2011
  7. 05/51 is_refname_available(): remove the "quiet" argumentmhagger@alum.mit.edu, Dec 12, 2011
  8. 06/51 parse_ref_line(): add docstringmhagger@alum.mit.edu, Dec 12, 2011
  9. 07/51 add_ref(): add docstringmhagger@alum.mit.edu, Dec 12, 2011
  10. 08/51 is_dup_ref(): extract function from sort_ref_array()mhagger@alum.mit.edu, Dec 12, 2011
  11. Jeff KingDec 12, 2011
  12. Michael HaggertyDec 12, 2011
  13. Junio C HamanoDec 12, 2011
  14. Junio C HamanoDec 12, 2011
  15. Michael HaggertyDec 13, 2011
  16. Michael HaggertyDec 13, 2011
  17. 09/51 refs: change signatures of get_packed_refs() and get_loose_refs()mhagger@alum.mit.edu, Dec 12, 2011
  18. 10/51 get_ref_dir(): change signaturemhagger@alum.mit.edu, Dec 12, 2011
  19. 11/51 resolve_gitlink_ref(): improve docstringmhagger@alum.mit.edu, Dec 12, 2011
  20. 12/51 Pass a (ref_cache *) to the resolve_gitlink_*() helper functionsmhagger@alum.mit.edu, Dec 12, 2011
  21. 13/51 resolve_gitlink_ref_recursive(): change to work with struct ref_cachemhagger@alum.mit.edu, Dec 12, 2011
  22. 14/51 repack_without_ref(): remove temporarymhagger@alum.mit.edu, Dec 12, 2011
  23. 15/51 create_ref_entry(): extract function from add_ref()mhagger@alum.mit.edu, Dec 12, 2011
  24. 16/51 add_ref(): take a (struct ref_entry *) parametermhagger@alum.mit.edu, Dec 12, 2011
  25. 17/51 do_for_each_ref(): correctly terminate while processesing extra_refsmhagger@alum.mit.edu, Dec 12, 2011
  26. Junio C HamanoDec 12, 2011
  27. 18/51 do_for_each_ref_in_array(): new functionmhagger@alum.mit.edu, Dec 12, 2011
  28. 19/51 do_for_each_ref_in_arrays(): new functionmhagger@alum.mit.edu, Dec 12, 2011
  29. 20/51 repack_without_ref(): reimplement using do_for_each_ref_in_array()mhagger@alum.mit.edu, Dec 12, 2011
  30. Junio C HamanoDec 12, 2011
  31. 21/51 names_conflict(): new function, extracted from is_refname_available()mhagger@alum.mit.edu, Dec 12, 2011
  32. 22/51 names_conflict(): simplify implementationmhagger@alum.mit.edu, Dec 12, 2011
  33. 23/51 is_refname_available(): reimplement using do_for_each_ref_in_array()mhagger@alum.mit.edu, Dec 12, 2011
  34. 24/51 refs.c: reorder definitions more logicallymhagger@alum.mit.edu, Dec 12, 2011
  35. 25/51 free_ref_entry(): new functionmhagger@alum.mit.edu, Dec 12, 2011
  36. 26/51 check_refname_component(): return 0 for zero-length componentsmhagger@alum.mit.edu, Dec 12, 2011
  37. 27/51 struct ref_entry: nest the value part in a unionmhagger@alum.mit.edu, Dec 12, 2011
  38. 28/51 refs.c: rename ref_array -> ref_dirmhagger@alum.mit.edu, Dec 12, 2011
  39. Junio C HamanoDec 13, 2011
  40. Michael HaggertyDec 13, 2011
  41. Junio C HamanoDec 13, 2011
  42. Michael HaggertyDec 13, 2011
  43. Junio C HamanoDec 13, 2011
  44. Michael HaggertyDec 13, 2011
  45. Junio C HamanoDec 13, 2011
  46. Junio C HamanoDec 14, 2011
  47. Jeff KingDec 14, 2011
  48. Michael HaggertyDec 15, 2011
  49. Jeff KingDec 15, 2011
  50. Michael HaggertyJan 17, 2012
  51. Michael HaggertyFeb 10, 2012
  52. Jeff KingFeb 10, 2012
  53. Junio C HamanoFeb 10, 2012
  54. Michael HaggertyFeb 11, 2012
  55. 29/51 refs: store references hierarchicallymhagger@alum.mit.edu, Dec 12, 2011
  56. 30/51 sort_ref_dir(): do not sort if already sortedmhagger@alum.mit.edu, Dec 12, 2011
  57. Junio C HamanoDec 12, 2011
  58. 31/51 refs: sort ref_dirs lazilymhagger@alum.mit.edu, Dec 12, 2011
  59. 32/51 do_for_each_ref(): only iterate over the subtree that was requestedmhagger@alum.mit.edu, Dec 12, 2011
  60. 33/51 get_ref_dir(): keep track of the current ref_dirmhagger@alum.mit.edu, Dec 12, 2011
  61. 34/51 refs: wrap top-level ref_dirs in ref_entriesmhagger@alum.mit.edu, Dec 12, 2011
  62. 35/51 get_packed_refs(): return (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  63. 36/51 get_loose_refs(): return (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  64. 37/51 is_refname_available(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  65. 38/51 find_ref(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  66. 39/51 read_packed_refs(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  67. 40/51 add_ref(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  68. 41/51 find_containing_direntry(): use (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  69. 42/51 search_ref_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  70. 43/51 add_entry(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  71. 44/51 do_for_each_ref_in_dir*(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  72. 45/51 sort_ref_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Dec 12, 2011
  73. 46/51 struct ref_dir: store a reference to the enclosing ref_cachemhagger@alum.mit.edu, Dec 12, 2011
  74. 47/51 read_loose_refs(): take a (ref_entry *) as argumentmhagger@alum.mit.edu, Dec 12, 2011
  75. 48/51 refs: read loose references lazilymhagger@alum.mit.edu, Dec 12, 2011
  76. 49/51 is_refname_available(): query only possibly-conflicting referencesmhagger@alum.mit.edu, Dec 12, 2011
  77. 50/51 read_packed_refs(): keep track of the directory being worked inmhagger@alum.mit.edu, Dec 12, 2011
  78. 51/51 repack_without_ref(): call clear_packed_ref_cache()mhagger@alum.mit.edu, Dec 12, 2011
  79. Junio C HamanoDec 12, 2011

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