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Re: [PATCH v2 08/11] refs/files: add a comment about refs_reflog_exists() call

From
Jeff King <peff@peff.net>
Date
Jul 20, 2021, 07:22 UTC
Message-ID
<YPZ5mzknK/nzKNCh@coredump.intra.peff.net>
In-Reply-To
<xmqqa6mintjx.fsf@gitster.g>
On Mon, Jul 19, 2021 at 09:43:14AM -0700, Junio C Hamano wrote:
Show 20 quoted lines
> >> +	 * such thing as a lock on the reflog, instead we always lock
> >> +	 * the "loose ref" (even if packet) above with
> >> +	 * lock_ref_oid_basic().
> >> +	 *
> >> +	 * If race happens we've got nothing more to do, we were asked
> >> +	 * to delete the reflog, and it's not there anymore. Great!
> >> +	 */
> >>  	if (!refs_reflog_exists(ref_store, refname)) {
> >>  		unlock_ref(lock);
> >>  		return 0;
> >
> > I think everything is accurate here, though I wouldn't have made the
> > distinction with "locking the loose ref". There is no such thing as
> > locking a packed ref; we always take the loose lock.
> >
> > s/packet/packed/, and maybe s/If race/If a race/.
> 
> Meaning, there is no such thing as locking a packed ref or a loose
> ref, we just lock a "ref" and the way it is done in files backend is
> by creating a lockfile as if we are creating/updating a loose one?

Yes, exactly. We do take a lock on the packed-refs file sometimes, but I generally think "lock the ref" always means to take refs/heads/foo.lock in the filesystem. Probably not all that important, but if we need a re-roll to clarify language anyway...:)

Show 13 quoted lines
> I do agree that the second sentence needs rewriting to make it less
> confusing.  lock_ref_oid_basic() being the way to lock "a ref" is
> not limited to cases where we want to do something to do to the
> reflog.
> 
> Taking all together, perhaps:
> 
> 	When refs are deleted, their reflog is deleted before the
> 	ref itself is deleted.  This is because there is no separate
> 	lock for reflog---instead we take a lock on the ref with
> 	lock_ref_oid_basic().
> 
>         If a race happens we've got nothing more to do...
Yeah, that reads fine to me.
-Peff
Previous: Junio C HamanoNext: Ævar Arnfjörð Bjarmason
Message 29 of 88 in “refs file backend: remove dead "errno == EISDIR" code”
  1. refs file backend: remove dead "errno == EISDIR" codeÆvar Arnfjörð Bjarmason, Jul 14, 2021
  2. Jeff KingJul 14, 2021
  3. Ævar Arnfjörð BjarmasonJul 14, 2021
  4. Jeff KingJul 14, 2021
  5. Ævar Arnfjörð BjarmasonJul 15, 2021
  6. Jeff KingJul 15, 2021
  7. Junio C HamanoJul 17, 2021
  8. Jeff KingJul 17, 2021
  9. Junio C HamanoJul 19, 2021
  10. Junio C HamanoJul 19, 2021
  11. Ævar Arnfjörð BjarmasonJul 17, 2021
  12. 00/11 fix "git reflog expire" race & get rid of EISDIR in refs APIÆvar Arnfjörð Bjarmason, Jul 16, 2021
  13. 01/11 refs/packet: add missing BUG() invocations to reflog callbacksÆvar Arnfjörð Bjarmason, Jul 16, 2021
  14. 02/11 refs/files: remove unused REF_DELETING in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 16, 2021
  15. Jeff KingJul 17, 2021
  16. Junio C HamanoJul 19, 2021
  17. Jeff KingJul 20, 2021
  18. 03/11 refs/files: remove unused "extras/skip" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 16, 2021
  19. 04/11 refs/files: remove unused "skip" in lock_raw_ref() tooÆvar Arnfjörð Bjarmason, Jul 16, 2021
  20. 05/11 refs/debug: re-indent argument list for "prepare"Ævar Arnfjörð Bjarmason, Jul 16, 2021
  21. 06/11 refs API: pass the "lock OID" to reflog "prepare"Ævar Arnfjörð Bjarmason, Jul 16, 2021
  22. Jeff KingJul 17, 2021
  23. Junio C HamanoJul 19, 2021
  24. Ævar Arnfjörð BjarmasonJul 19, 2021
  25. 07/11 refs: make repo_dwim_log() accept a NULL oidÆvar Arnfjörð Bjarmason, Jul 16, 2021
  26. 08/11 refs/files: add a comment about refs_reflog_exists() callÆvar Arnfjörð Bjarmason, Jul 16, 2021
  27. Jeff KingJul 17, 2021
  28. Junio C HamanoJul 19, 2021
  29. Jeff KingJul 20, 2021
  30. 09/11 reflog expire: don't lock reflogs using previously seen OIDÆvar Arnfjörð Bjarmason, Jul 16, 2021
  31. Jeff KingJul 17, 2021
  32. Han-Wen NienhuysAug 17, 2021
  33. Junio C HamanoAug 18, 2021
  34. Carlo Marcelo Arenas BelónAug 19, 2021
  35. Junio C HamanoAug 20, 2021
  36. 10/11 refs/files: remove unused "oid" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 16, 2021
  37. Jeff KingJul 17, 2021
  38. 11/11 refs/files: remove unused "errno == EISDIR" codeÆvar Arnfjörð Bjarmason, Jul 16, 2021
  39. Jeff KingJul 17, 2021
  40. Jeff KingJul 17, 2021
  41. 00/12 fix "git reflog expire" race & get rid of EISDIR in refs APIÆvar Arnfjörð Bjarmason, Jul 20, 2021
  42. 10/12 refs/files: remove unused "oid" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 20, 2021
  43. 05/12 refs/debug: re-indent argument list for "prepare"Ævar Arnfjörð Bjarmason, Jul 20, 2021
  44. 08/12 refs/files: add a comment about refs_reflog_exists() callÆvar Arnfjörð Bjarmason, Jul 20, 2021
  45. 07/12 refs: make repo_dwim_log() accept a NULL oidÆvar Arnfjörð Bjarmason, Jul 20, 2021
  46. 02/12 refs/files: remove unused REF_DELETING in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 20, 2021
  47. Junio C HamanoAug 2, 2021
  48. 01/12 refs/packet: add missing BUG() invocations to reflog callbacksÆvar Arnfjörð Bjarmason, Jul 20, 2021
  49. 11/12 refs/files: remove unused "errno == EISDIR" codeÆvar Arnfjörð Bjarmason, Jul 20, 2021
  50. 09/12 reflog expire: don't lock reflogs using previously seen OIDÆvar Arnfjörð Bjarmason, Jul 20, 2021
  51. 03/12 refs/files: remove unused "extras/skip" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 20, 2021
  52. 06/12 refs API: pass the "lock OID" to reflog "prepare"Ævar Arnfjörð Bjarmason, Jul 20, 2021
  53. Junio C HamanoJul 21, 2021
  54. Junio C HamanoJul 21, 2021
  55. 12/12 refs/files: remove unused "errno != ENOTDIR" conditionÆvar Arnfjörð Bjarmason, Jul 20, 2021
  56. 04/12 refs/files: remove unused "skip" in lock_raw_ref() tooÆvar Arnfjörð Bjarmason, Jul 20, 2021
  57. 00/11 fix "git reflog expire" race & get rid of EISDIR in refs APIÆvar Arnfjörð Bjarmason, Jul 26, 2021
  58. 02/11 refs/files: remove unused REF_DELETING in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 26, 2021
  59. 01/11 refs/packet: add missing BUG() invocations to reflog callbacksÆvar Arnfjörð Bjarmason, Jul 26, 2021
  60. 03/11 refs/files: remove unused "extras/skip" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 26, 2021
  61. 05/11 refs/debug: re-indent argument list for "prepare"Ævar Arnfjörð Bjarmason, Jul 26, 2021
  62. 04/11 refs/files: remove unused "skip" in lock_raw_ref() tooÆvar Arnfjörð Bjarmason, Jul 26, 2021
  63. 07/11 refs/files: add a comment about refs_reflog_exists() callÆvar Arnfjörð Bjarmason, Jul 26, 2021
  64. 09/11 refs/files: remove unused "oid" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Jul 26, 2021
  65. 08/11 reflog expire: don't lock reflogs using previously seen OIDÆvar Arnfjörð Bjarmason, Jul 26, 2021
  66. Junio C HamanoAug 2, 2021
  67. Ævar Arnfjörð BjarmasonAug 4, 2021
  68. 10/11 refs/files: remove unused "errno == EISDIR" codeÆvar Arnfjörð Bjarmason, Jul 26, 2021
  69. 11/11 refs/files: remove unused "errno != ENOTDIR" conditionÆvar Arnfjörð Bjarmason, Jul 26, 2021
  70. 06/11 refs: make repo_dwim_log() accept a NULL oidÆvar Arnfjörð Bjarmason, Jul 26, 2021
  71. 00/13 fix "git reflog expire" race & get rid of EISDIR in refs APIÆvar Arnfjörð Bjarmason, Aug 23, 2021
  72. 01/13 refs/packet: add missing BUG() invocations to reflog callbacksÆvar Arnfjörð Bjarmason, Aug 23, 2021
  73. 02/13 refs/files: remove unused REF_DELETING in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Aug 23, 2021
  74. 03/13 refs: drop unused "flags" parameter to lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Aug 23, 2021
  75. 04/13 refs/files: remove unused "extras/skip" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Aug 23, 2021
  76. 05/13 refs/files: remove unused "skip" in lock_raw_ref() tooÆvar Arnfjörð Bjarmason, Aug 23, 2021
  77. 06/13 refs/debug: re-indent argument list for "prepare"Ævar Arnfjörð Bjarmason, Aug 23, 2021
  78. 07/13 refs: make repo_dwim_log() accept a NULL oidÆvar Arnfjörð Bjarmason, Aug 23, 2021
  79. 08/13 refs/files: add a comment about refs_reflog_exists() callÆvar Arnfjörð Bjarmason, Aug 23, 2021
  80. 09/13 reflog expire: don't lock reflogs using previously seen OIDÆvar Arnfjörð Bjarmason, Aug 23, 2021
  81. 10/13 refs API: remove OID argument to reflog_expire()Ævar Arnfjörð Bjarmason, Aug 23, 2021
  82. 11/13 refs/files: remove unused "oid" in lock_ref_oid_basic()Ævar Arnfjörð Bjarmason, Aug 23, 2021
  83. 12/13 refs/files: remove unused "errno == EISDIR" codeÆvar Arnfjörð Bjarmason, Aug 23, 2021
  84. 13/13 refs/files: remove unused "errno != ENOTDIR" conditionÆvar Arnfjörð Bjarmason, Aug 23, 2021
  85. Ævar Arnfjörð BjarmasonJul 23, 2021
  86. Junio C HamanoJul 23, 2021
  87. Ævar Arnfjörð BjarmasonJul 26, 2021
  88. Junio C HamanoJul 26, 2021

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