Re: [PATCH 2/3] t/lib-httpd: make http-429 first-request check atomic

>
> "Michael Montalbo via GitGitGadget" <gitgitgadget@gmail.com> writes:
>
> > -# Check if this is the first call (no state file exists)
> > -if test -f "$state_file"
> > +# Apache can run this CGI for concurrent requests, so the script decides
> > +# whether this is the first call with a single atomic "mkdir": it succeeds for
> > +# exactly one of any racing requests and fails for the rest. "permanent"
> > +# always rate-limits and records no state.
> > +if test "$retry_after" != permanent && ! mkdir "$state" 2>/dev/null
>
> I think the last sentence in the above comment was meant to explain
> why the new code checks the value of "$retry_after", but it is not
> clear if it is needed for correctness (in other words, the original
> was wrong to do "test -f && touch" but also was wrong to do so even
> when "$retry_after" is set to "permanent), or if it is a mere
> "optimization opportunity" you are taking advantage of.  In either
> case, it would be nice to see it explained in the proposed commit
> log message.
>