test-lib-functions: simplify packetize() stdin code

Commit Message

Jeff King March 29, 2020, 3:02 p.m. UTC

On Sat, Mar 28, 2020 at 07:20:10AM -0400, Jeff King wrote:

> > 	perl -e '
> > 		my $data = do { local $?; <STDIN> };
> >                 printf "%04x%s", length($data), $data;
> > 	'
> > 
> > That's one process but much heavier than cat/wc/printf/cat, I guess.
> 
> Yeah, I was tempted to do that, but ${#packet} is even one process
> shorter. :) It might be worth simplifying the stdin path above, but it's
> much less important if most of those call-sites go away.

Here it is as a patch on top. I doubt it matters that much (there are
only two stdin calls in the whole suite). So I'm not sure if this patch
should be "eh, why not?" or "meh, pointless churn".

-- >8 --
Subject: [PATCH] test-lib-functions: simplify packetize() stdin code

The code path in packetize() for reading stdin needs to handle NUL
bytes, so we can't rely on shell variables. However, the current code
takes a whopping 4 processes and uses a temporary file. We can do this
much more simply and efficiently by using a single perl invocation (and
we already rely on perl in the matching depacketize() function).

We'll keep the non-stdin code path as it is, since that uses zero extra
processes.

Signed-off-by: Jeff King <[e-mail]>
---
 t/test-lib-functions.sh | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Comments

Junio C Hamano March 29, 2020, 3:49 p.m. UTC | #1

Jeff King <[e-mail]> writes:

> Here it is as a patch on top. I doubt it matters that much (there are
> only two stdin calls in the whole suite). So I'm not sure if this patch
> should be "eh, why not?" or "meh, pointless churn".

Me, neither. ;-)

Patch

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 216918a58c..88b7dbd69a 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -1373,11 +1373,10 @@  packetize() {
 		packet="$*"
 		printf '%04x%s' "$((4 + ${#packet}))" "$packet"
 	else
-		cat >packetize.tmp &&
-		len=$(wc -c <packetize.tmp) &&
-		printf '%04x' "$(($len + 4))" &&
-		cat packetize.tmp &&
-		rm -f packetize.tmp
+		perl -e '
+			my $packet = do { local $/; <STDIN> };
+			printf "%04x%s", 4 + length($packet), $packet;
+		'
 	fi
 }