On Thu, Oct 20, 2016 at 12:54:32PM -0700, Stefan Beller wrote:
> Maybe we should stop introducing un-optimized tests.
> [...]
> * heavy use of the "git -C <dir>" pattern. When applying that
> thouroughly we'd save spanning the subshells.
Yeah, I imagine with some style changes we could drop quite a few
subshells. The problem is that the conversion work is manual and
tedious. I'd look first for spots where we can eliminate thousands of
calls with a single change.
> That said I really like the idea of having a helper that would eliminate the cat
> for you, e.g. :
>
> git_test_helper_equal_stdin_or_diff_and_die -C super_repo status
> --porcelain=v2 --branch --untracked-files=all <<-EOF
> 1 A. N... 000000 100644 100644 $_z40 $HMOD .gitmodules
> 1 AM S.M. 000000 160000 160000 $_z40 $HSUP sub1
> EOF
I think that helper still ends up using "cat" and "diff" under the hood,
unless you write those bits in pure shell. But at that point, I suspect
we could "cat" and "test_cmp" in pure shell, something like:
cat () {
# optimize common here-doc usage
if test $# -eq 0
then
while read -r line
do
printf '%s' "$line"
done
fi
command cat "$@"
}
test_cmp () {
# optimize for common "they are the same" case
# without any subshells or subprograms
while true; do
if ! read -r line1 <&3
then
if ! read -r line2 <&4
# EOF on both; good
return 0
else
# EOF only on file1; fail
break
fi
fi
if ! read -r line2 <&4
then
# EOF only on file2; fail
break
fi
test "$line1" = "$line2" || break
done 3<"$1" 4<"$2"
# if we get here, the optimized version found some
# difference. We can just "return 1", but let's run
# the real $GIT_TEST_CMP to provide pretty output.
# This should generally only happen on test failures,
# so performance isn't a big deal.
"$GIT_TEST_CMP" "$@"
}
Those are both completely untested. But maybe they are worth playing
around with for somebody on Windows to see if they make a dent in the
test runtime.
-Peff