Re: p2000 failure due to empty reflog

On Mon, Oct 04 2021, Derrick Stolee wrote:

On 10/2/2021 1:37 PM, René Scharfe wrote:

quoted

p2000 fails for me and reports:

   perf 18 - git checkout -f - (full-v3):
   running:
   			(
   				cd full-v3 &&
   				echo >>f2/f4/a &&
   				git checkout -f -
   			)

   error: pathspec '-' did not match any file(s) known to git

checkout fails because the reflog is empty, so the "-" can't be
resolved.  The pathspec error message is confusing, though.

The patch below adds a reflog entry and allows the script to
succeed.

Before the "test_perf_on_all git commit -a -m A", there are two
reflog entries in each of the five clones, after it there are
none.  How is that even possible?

That is certainly confusing. Is there something about your global
(or local to your test repo) GC settings that cause an auto-GC to
prune the reflog aggressively?

Perhaps something to do with certain parts of the code doing a
time(NULL), and other parts faking up times to be 2005-something?

I have some WIP patches that run concurrent "git gc --auto" with a
detach across the whole test suite, and IIRC I had to search/replace all
time(NULL) with my own time() that faked up (looks it up) an epoch of
1113465166 to avoid this exact issue.

If you try doing that across our tests I think you'll find that the
@{-1} syntax (reflog-powered) will start failing.

But that's from vague memory, but perhaps it'll point you in the right
direction...