Re: [PATCH] t/perf: depend on perl JSON only when using --codespeed

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> Commit 05eb1c37ed (perf/aggregate: implement codespeed JSON output,
> 2018-01-05) added a dependency on the perl JSON module to show output
> from aggregate.perl, but we only need it when the user asks for
> --codespeed output. While the module is pretty common, it's not part of
> the base system, and this dependency can get in the way of producing the
> default human-readable output.
>
> Let's bump the "use" down to a "require" in the code path that needs it,
> which will be interpreted at run-time instead of compile-time. People
> not using "--codespeed" won't even load the module, and anybody using it
> should see the same results (including the same perl error if they don't
> have it).

Nice.

> This bites me occasionally when running perf tests on many-core work
> machines where I can't just "apt-get install libjson-perl". So I finally
> decided look into it. :)

Thanks.

>  t/perf/aggregate.perl | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/t/perf/aggregate.perl b/t/perf/aggregate.perl
> index 494907a892..76dd48f890 100755
> --- a/t/perf/aggregate.perl
> +++ b/t/perf/aggregate.perl
> @@ -3,7 +3,6 @@
>  use lib '../../perl/build/lib';
>  use strict;
>  use warnings;
> -use JSON;
>  use Getopt::Long;
>  use Git;
>  
> @@ -342,7 +341,8 @@ sub print_codespeed_results {
>  		}
>  	}
>  
> -	print to_json(\@data, {utf8 => 1, pretty => 1, canonical => 1}), "\n";
> +	require JSON;
> +	print JSON::to_json(\@data, {utf8 => 1, pretty => 1, canonical => 1}), "\n";
>  }
>  
>  binmode STDOUT, ":utf8" or die "PANIC on binmode: $!";