Re: [PATCH v2 5/7] t0027: cache expected output files

[Patrick Steinhardt <ps@pks.im>]

On Mon, Nov 09, 2026 at 03:46:51PM +0100, Torsten Bögershausen wrote:
> On Mon, Nov 09, 2026 at 10:58:26AM +0100, Patrick Steinhardt wrote:
> > In the preceding commit we have optimized one aspect of t0027 already.
> > Another inefficiency is `compare_files ()` and `compare_ws_file ()`,
> > which are both called more than a 1000 times.
> > 
> > These functions will repeatedly generate the same expected outcome even
> > though there's only a small handful of input files that the expected
> > outcome is computed from. Recomputing those every time is of course
> > quite pointless.
> > 
> > Improve this by computing the expected outcome once, only, to reduce the
> > number of spawned processes. This reduces the runtime by around 20-25%,
> > and on Windows the runtime decreases from 480 to 380 seconds.
> > 
> > Signed-off-by: Patrick Steinhardt <ps@pks.im>
> > ---
> >  t/t0027-auto-crlf.sh | 17 +++++++++--------
> >  1 file changed, 9 insertions(+), 8 deletions(-)
> > 
> > diff --git a/t/t0027-auto-crlf.sh b/t/t0027-auto-crlf.sh
> > index 504a7ea54bb..b021f0855a8 100755
> > --- a/t/t0027-auto-crlf.sh
> > +++ b/t/t0027-auto-crlf.sh
> > @@ -5,22 +5,23 @@ test_description='CRLF conversion all combinations'
> >  . ./test-lib.sh
> >  
> >  compare_files () {
> > -	tr '\015\000' QN <"$1" >"$1".expect &&
> > +	{ test -f "$1".expect || tr '\015\000' QN <"$1" >"$1".expect; } &&
> >  	tr '\015\000' QN <"$2" | tr -d 'Z' >"$2".actual &&
> > -	test_cmp "$1".expect "$2".actual &&
> > -	rm "$1".expect "$2".actual
> > +	test_cmp "$1".expect "$2".actual
> >  }
> >  
> 
> Nice.
> If you want to save even more CPU/SSD-cycles,
> you can prepare the expect files like this:
> (No, I didn't do any benchmarks, nor look at ws_compare)

Thanks! I benchmarked this and it doesn't seem to make much of a
difference. So I'd propose to stick with the simple change for now, if
that's alright with you.

Patrick