Re: [PATCH] send-email: more meaningful Message-ID

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 5, 2016, 21:10 UTC
Message-ID: <xmqqinzv224x.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20160405193952.5849-1-normalperson@yhbt.net>

Eric Wong <normalperson@yhbt.net> writes:

Show 15 quoted lines

> Using a YYYYmmddHHMMSS date representation is more meaningful to
> humans, especially when used for lookups on NNTP servers or linking
> to archive sites via Message-ID (e.g. mid.gmane.org or
> mid.mail-archive.com).  This timestamp format more easily gives a
> reader of the URL itself a rough date of a linked message compared
> to having them calculate the seconds since the Unix epoch.
>
> Furthermore, having the MUA name in the Message-ID seems to be a
> rare oddity I haven't noticed outside of git-send-email.  We
> already have an optional X-Mailer header field to advertise for
> us, so extending the Message-ID by 15 characters can make for
> unpleasant Message-ID-based URLs to archive sites.
>
> Signed-off-by: Eric Wong <normalperson@yhbt.net>
> ---

Sounds like a sensible goal.  Just a few comments.

 - Is it safe to assume that we always can use POSIX::strftime(), or
   do we need some fallback?  I am guessing that this is safe, as
   POSIX has been part of the core modules for a long time, and the
   script does "use 5.008" upfront.

 - It is my understanding that, as "use" is a compilation-time
   thing, hiding it inside a block does not help reducing the
   start-up overhead (people can use "require" if they want to do a
   lazy loading and optionally a fallback).  Is my Perl5 outdated?
   Otherwise, let's have it near the beginning of the script, close
   to where we use Term::ReadLine and others.

Thanks.

Show 26 quoted lines

>  git-send-email.perl | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/git-send-email.perl b/git-send-email.perl
> index d356901..23141e7 100755
> --- a/git-send-email.perl
> +++ b/git-send-email.perl
> @@ -949,7 +949,8 @@ my ($message_id_stamp, $message_id_serial);
>  sub make_message_id {
>  	my $uniq;
>  	if (!defined $message_id_stamp) {
> -		$message_id_stamp = sprintf("%s-%s", time, $$);
> +		use POSIX qw/strftime/;
> +		$message_id_stamp = strftime("%Y%m%d%H%M%S.$$", gmtime(time));
>  		$message_id_serial = 0;
>  	}
>  	$message_id_serial++;
> @@ -964,7 +965,7 @@ sub make_message_id {
>  		require Sys::Hostname;
>  		$du_part = 'user@' . Sys::Hostname::hostname();
>  	}
> -	my $message_id_template = "<%s-git-send-email-%s>";
> +	my $message_id_template = "<%s-%s>";
>  	$message_id = sprintf($message_id_template, $uniq, $du_part);
>  	#print "new message id = $message_id\n"; # Was useful for debugging
>  }