Michael Haggerty wrote:
> It could be that some other process is trying to clean up empty
> directories at the same time that safe_create_leading_directories() is
> attempting to create them. In this case, it could happen that
> directory "a/b" was present at the end of one iteration of the loop
> (either it was already present or we just created it ourselves), but
> by the time we try to create directory "a/b/c", directory "a/b" has
> been deleted. In fact, directory "a" might also have been deleted.
When does this happen in practice? Is this about git racing with
itself or with some other program?
I fear that the aggressive directory creator fighting the aggressive
directory remover might be waging a losing battle.
Is this about a push that creates a ref racing against a push that
deletes a ref from the same hierarchy?
> So, if a call to mkdir() fails with ENOENT, then try checking/making
> all directories again from the beginning. Attempt up to three times
> before giving up.
If we are racing against a ref deletion, then we can retry while our
rival keeps walking up the directory tree and deleting parent
directories. As soon as we successfully create a directory, we have
won the race.
But what happens if the entire safe_create_leading_directories
operation succeeds and *then* our racing partner deletes the
directory? No one is putting in a file to reserve the directory for
the directory creator.
If we care enough to retry more than once, I fear this is retrying at
the wrong level.
> Signed-off-by: Michael Haggerty <mhag...@alum.mit.edu>
> sha1_file.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
The code is clear and implements the design correctly.
Thanks for some food for thought,
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