From: Junio C Hamano <gitster@pobox•com>
To: Michael Haggerty <mhagger@alum•mit.edu>
Cc: Jonathan Nieder <jrnieder@gmail•com>,
Ramsay Jones <ramsay@ramsay1•demon.co.uk>,
git@vger•kernel.org
Subject: Re: [PATCH v2 10/17] lock_ref_sha1_basic(): on SCLD_VANISHED, retry
Date: Mon, 06 Jan 2014 09:54:25 -0800 [thread overview]
Message-ID: <xmqq4n5hj8ry.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <1389015935-21936-11-git-send-email-mhagger@alum.mit.edu> (Michael Haggerty's message of "Mon, 6 Jan 2014 14:45:28 +0100")
Michael Haggerty <mhagger@alum•mit.edu> writes:
> If safe_create_leading_directories() fails because a file along the
> path unexpectedly vanished, try again (up to 3 times).
>
> This can occur if another process is deleting directories at the same
> time as we are trying to make them. For example, "git pack-refs
> --all" tries to delete the loose refs and any empty directories that
> are left behind. If a pack-refs process is running, then it might
> delete a directory that we need to put a new loose reference in.
>
> If safe_create_leading_directories() thinks this might have happened,
> then take its advice and try again (maximum three attempts).
>
> Signed-off-by: Michael Haggerty <mhagger@alum•mit.edu>
> ---
> refs.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/refs.c b/refs.c
> index 3926136..6eb8a02 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -2039,6 +2039,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
> int type, lflags;
> int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
> int missing = 0;
> + int attempts = 3;
>
> lock = xcalloc(1, sizeof(struct ref_lock));
> lock->lock_fd = -1;
> @@ -2093,7 +2094,15 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
> if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
> lock->force_write = 1;
>
> - if (safe_create_leading_directories(ref_file)) {
> + retry:
> + switch (safe_create_leading_directories(ref_file)) {
> + case SCLD_OK:
> + break; /* success */
> + case SCLD_VANISHED:
> + if (--attempts > 0)
> + goto retry;
> + /* fall through */
Hmph.
Having no backoff/sleep at all might be OK here as long as the other
side that removes does not retry (and I do not think the other side
would, even though I haven't read through the series to the end yet
;-)).
This may be just a style thing, but I find that the variable name
"attempts" that starts out as 3 quite misleading, as its value is
not "the number of attempts made" but "the remaining number of
attempts allowed." Starting it from 0 and then
if (attempts++ < MAX_ATTEMPTS)
goto retry;
would be one way to clarify it. Renaming it to remaining_attempts
would be another.
> + default:
> last_errno = errno;
> error("unable to create directory for %s", ref_file);
> goto error_return;
next prev parent reply other threads:[~2014-01-06 17:54 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-06 13:45 [PATCH v2 00/17] Fix some mkdir/rmdir races Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 01/17] safe_create_leading_directories(): fix format of "if" chaining Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 02/17] safe_create_leading_directories(): reduce scope of local variable Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 03/17] safe_create_leading_directories(): add explicit "slash" pointer Michael Haggerty
2014-01-06 18:32 ` Junio C Hamano
2014-01-07 9:26 ` Michael Haggerty
2014-01-07 17:41 ` Junio C Hamano
2014-01-19 20:31 ` Sebastian Schuberth
2014-01-06 13:45 ` [PATCH v2 04/17] safe_create_leading_directories(): rename local variable Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 05/17] safe_create_leading_directories(): split on first of multiple slashes Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 06/17] safe_create_leading_directories(): always restore slash at end of loop Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 07/17] safe_create_leading_directories(): introduce enum for return values Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 08/17] cmd_init_db(): when creating directories, handle errors conservatively Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 09/17] safe_create_leading_directories(): add new error value SCLD_VANISHED Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 10/17] lock_ref_sha1_basic(): on SCLD_VANISHED, retry Michael Haggerty
2014-01-06 17:54 ` Junio C Hamano [this message]
2014-01-07 10:25 ` Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 11/17] lock_ref_sha1_basic(): if locking fails with ENOENT, retry Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 12/17] remove_dir_recurse(): tighten condition for removing unreadable dir Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 13/17] remove_dir_recurse(): handle disappearing files and directories Michael Haggerty
2014-01-06 18:18 ` Junio C Hamano
2014-01-07 10:07 ` Michael Haggerty
2014-01-07 17:27 ` Junio C Hamano
2014-01-06 13:45 ` [PATCH v2 14/17] rename_ref(): extract function rename_tmp_log() Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 15/17] rename_tmp_log(): handle a possible mkdir/rmdir race Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 16/17] rename_tmp_log(): limit the number of remote_empty_directories() attempts Michael Haggerty
2014-01-06 13:45 ` [PATCH v2 17/17] rename_tmp_log(): on SCLD_VANISHED, retry Michael Haggerty
2014-01-06 18:21 ` Junio C Hamano
2014-01-07 10:50 ` Michael Haggerty
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=xmqq4n5hj8ry.fsf@gitster.dls.corp.google.com \
--to=gitster@pobox$(echo .)com \
--cc=git@vger$(echo .)kernel.org \
--cc=jrnieder@gmail$(echo .)com \
--cc=mhagger@alum$(echo .)mit.edu \
--cc=ramsay@ramsay1$(echo .)demon.co.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox