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Re: [PATCH v6 08/42] refs.c: change ref_transaction_update() to do error checking and return status

From
Ronnie Sahlberg <sahlberg@google.com>
Date
May 15, 2014, 16:06 UTC
Message-ID
<CAL=YDW=e1FdVn5cHvRHPQrA8ywPne-uZk_iYNO4EmxJEA=fHSw@mail.gmail.com>
In-Reply-To
<20140514234015.GE9218@google.com>
On Wed, May 14, 2014 at 4:40 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:
Show 20 quoted lines
> Ronnie Sahlberg wrote:
>
>> Update ref_transaction_update() do some basic error checking and return
>> true on error. Update all callers to check ref_transaction_update() for error.
>> There are currently no conditions in _update that will return error but there
>> will be in the future.
>>
>> Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
>> ---
>>  builtin/update-ref.c | 10 ++++++----
>>  refs.c               |  9 +++++++--
>>  refs.h               | 10 +++++-----
>>  3 files changed, 18 insertions(+), 11 deletions(-)
>
> Revisiting comments from [1]:
>
>  * When I call ref_transaction_update, what does it mean that I get
>    a nonzero return value?  Does it mean the _update failed and had
>    no effect?  What will I want to do next: should I try again or
>    print an error and exit?

It means the transaction will no longer work and must be rolled back. See below for the updated text I added to refs.h

Show 5 quoted lines
>
>    Ideally I should be able to answer these questions by reading
>    the signature of ref_transaction_update and the comment documenting
>    it.  The comment doesn't say anything about what errors
>    mean here.
I have updated the description to include :
 * Function returns 0 on success and non-zero on failure. A failure to update
 * means that the transaction as a whole has failed and will need to be
 * rolled back.
Show 5 quoted lines
>
>  * the error message change for the have_old && !old_sha1 case (to add
>    "BUG:" so users know the impossible has happened and translators
>    know not to bother with it) seems to have snuck ahead into patch 28
>    (refs.c: add transaction.status and track OPEN/CLOSED/ERROR).
Done.
Show 6 quoted lines
>
>  * It would be easier to make sense of the error path (does the error
>    message have enough information?  Will the user be bewildered?)
>    if there were an example of how ref_transaction_update can fail.
>
>    There still doesn't seem to be one by the end of the series.

This patch series got a lot longer than I initially thought so I did not get to the point where we it would make sense to start returning !0. :-(

The next patchseries I sent out for review does add things to _update that will cause it to return failures. For example, locking the ref there happens in _update instead of _commit and then it starts make sense to return failures back to the caller for things such as "Multiple updates for ref '%s' not allowed."

Unfortunate but since this patch series reached >40 patches I did not want to continue expanding on it. This means that actually starting to use "let _update return error" did not actually start becomming used until the second patch series, which now is well over 30 patches in size :-(

I just felt I had to stop growing this series or it would never be finished.
Show 7 quoted lines
>
> The general idea still seems sensible.
>
> Thanks,
> Jonathan
>
> [1] http://thread.gmane.org/gmane.comp.version-control.git/246437/focus=247115
Previous: Jonathan NiederNext: Ronnie Sahlberg
Message 24 of 78 in “Use ref transactions for all ref updates”
  1. 00/42 Use ref transactions for all ref updatesRonnie Sahlberg, May 1, 2014
  2. 01/42 refs.c: constify the sha arguments for ref_transaction_create|delete|updateRonnie Sahlberg, May 1, 2014
  3. 02/42 refs.c: allow passing NULL to ref_transaction_freeRonnie Sahlberg, May 1, 2014
  4. Jonathan NiederMay 13, 2014
  5. Ronnie SahlbergMay 13, 2014
  6. Ronnie SahlbergMay 14, 2014
  7. 03/42 refs.c: add a strbuf argument to ref_transaction_commit for error loggingRonnie Sahlberg, May 1, 2014
  8. Jonathan NiederMay 13, 2014
  9. Ronnie SahlbergMay 14, 2014
  10. 04/42 refs.c: make ref_update_reject_duplicates take a strbuf argument for errorsRonnie Sahlberg, May 1, 2014
  11. Jonathan NiederMay 14, 2014
  12. Ronnie SahlbergMay 14, 2014
  13. 05/42 update-ref.c: log transaction error from the update_refRonnie Sahlberg, May 1, 2014
  14. Jonathan NiederMay 14, 2014
  15. Ronnie SahlbergMay 15, 2014
  16. 06/42 refs.c: make update_ref_write update a strbuf on failureRonnie Sahlberg, May 1, 2014
  17. Jonathan NiederMay 14, 2014
  18. 07/42 refs.c: remove the onerr argument to ref_transaction_commitRonnie Sahlberg, May 1, 2014
  19. Jonathan NiederMay 14, 2014
  20. 08/42 refs.c: change ref_transaction_update() to do error checking and return statusRonnie Sahlberg, May 1, 2014
  21. Michael HaggertyMay 5, 2014
  22. Ronnie SahlbergMay 5, 2014
  23. Jonathan NiederMay 14, 2014
  24. Ronnie SahlbergMay 15, 2014
  25. 09/42 refs.c: change ref_transaction_create to do error checking and return statusRonnie Sahlberg, May 1, 2014
  26. Jonathan NiederMay 15, 2014
  27. Ronnie SahlbergMay 15, 2014
  28. Jonathan NiederMay 15, 2014
  29. 10/42 refs.c: ref_transaction_delete to check for error and return statusRonnie Sahlberg, May 1, 2014
  30. Jonathan NiederMay 15, 2014
  31. Ronnie SahlbergMay 15, 2014
  32. 11/42 tag.c: use ref transactions when doing updatesRonnie Sahlberg, May 1, 2014
  33. Jonathan NiederMay 15, 2014
  34. Ronnie SahlbergMay 15, 2014
  35. Jonathan NiederMay 15, 2014
  36. 12/42 replace.c: use the ref transaction functions for updatesRonnie Sahlberg, May 1, 2014
  37. Jonathan NiederMay 15, 2014
  38. Ronnie SahlbergMay 15, 2014
  39. 13/42 commit.c: use ref transactions for updatesRonnie Sahlberg, May 1, 2014
  40. Jonathan NiederMay 15, 2014
  41. Ronnie SahlbergMay 15, 2014
  42. 14/42 sequencer.c: use ref transactions for all ref updatesRonnie Sahlberg, May 1, 2014
  43. Jonathan NiederMay 15, 2014
  44. 15/42 fast-import.c: change update_branch to use ref transactionsRonnie Sahlberg, May 1, 2014
  45. 16/42 branch.c: use ref transaction for all ref updatesRonnie Sahlberg, May 1, 2014
  46. 17/42 refs.c: change update_ref to use a transactionRonnie Sahlberg, May 1, 2014
  47. 18/42 refs.c: free the transaction before returning when number of updates is 0Ronnie Sahlberg, May 1, 2014
  48. 19/42 refs.c: ref_transaction_commit should not free the transactionRonnie Sahlberg, May 1, 2014
  49. 20/42 fetch.c: clear errno before calling functions that might set itRonnie Sahlberg, May 1, 2014
  50. Eric SunshineMay 2, 2014
  51. Ronnie SahlbergMay 2, 2014
  52. 21/42 fetch.c: change s_update_ref to use a ref transactionRonnie Sahlberg, May 1, 2014
  53. 22/42 fetch.c: use a single ref transaction for all ref updatesRonnie Sahlberg, May 1, 2014
  54. 23/42 receive-pack.c: use a reference transaction for updating the refsRonnie Sahlberg, May 1, 2014
  55. 24/42 fast-import.c: use a ref transaction when dumping tagsRonnie Sahlberg, May 1, 2014
  56. 25/42 walker.c: use ref transaction for ref updatesRonnie Sahlberg, May 1, 2014
  57. 26/42 refs.c: make write_ref_sha1 staticRonnie Sahlberg, May 1, 2014
  58. 27/42 refs.c: make lock_ref_sha1 staticRonnie Sahlberg, May 1, 2014
  59. 28/42 refs.c: add transaction.status and track OPEN/CLOSED/ERRORRonnie Sahlberg, May 1, 2014
  60. 29/42 refs.c: remove the update_ref_lock functionRonnie Sahlberg, May 1, 2014
  61. 30/42 refs.c: remove the update_ref_write functionRonnie Sahlberg, May 1, 2014
  62. 31/42 refs.c: remove lock_ref_sha1Ronnie Sahlberg, May 1, 2014
  63. 32/42 refs.c: make prune_ref use a transaction to delete the refRonnie Sahlberg, May 1, 2014
  64. 33/42 refs.c: make delete_ref use a transactionRonnie Sahlberg, May 1, 2014
  65. 34/42 refs.c: pass the ref log message to _create/delete/update instead of _commitRonnie Sahlberg, May 1, 2014
  66. 35/42 refs.c: pass NULL as *flags to read_ref_fullRonnie Sahlberg, May 1, 2014
  67. 36/42 refs.c: pack all refs before we start to rename a refRonnie Sahlberg, May 1, 2014
  68. 37/42 refs.c: move the check for valid refname to lock_ref_sha1_basicRonnie Sahlberg, May 1, 2014
  69. 38/42 refs.c: call lock_ref_sha1_basic directly from commitRonnie Sahlberg, May 1, 2014
  70. 39/42 refs.c: add a new flag for transaction delete for refs we know are packed onlyRonnie Sahlberg, May 1, 2014
  71. 40/42 refs.c: pass a skip list to name_conflict_fnRonnie Sahlberg, May 1, 2014
  72. Eric SunshineMay 2, 2014
  73. Ronnie SahlbergMay 2, 2014
  74. 41/42 refs.c: make rename_ref use a transactionRonnie Sahlberg, May 1, 2014
  75. 42/42 refs.c: remove forward declaraion of write_ref_sha1Ronnie Sahlberg, May 1, 2014
  76. Michael HaggertyMay 5, 2014
  77. Ronnie SahlbergMay 5, 2014
  78. Jonathan NiederMay 13, 2014

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