Re: x86 SHA1: Faster than OpenSSL

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 4, 2009, 20:41 UTC
Message-ID: <7vljlzjorh.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20090804080147.15201.qmail@science.horizon.com>

"George Spelvin" <linux@horizon.com> writes:

> The one question I have is that currently perl is not a critical
> compile-time dependency; it's needed for some extra stuff, but AFAIK you
> can get most of git working without it.  Whether to add that dependency
> or what is a Junio question.

I am actually feel a lot more uneasy to apply a patch signed of by somebody who calls himself George Spelvin, though.

Three classes of people compile git from the source:

 * People who want to be on the bleeding edge and compile git for
   themselves, even though they are on mainstream platforms where they
   could choose distro-packaged one;

 * People who produce binary packages for distribution.

 * People who are on minority platforms and have no other way to get git
   than compiling for themselves;

We do not have to worry about the first two groups of people. It won't be too involved for them to install Perl on their system; after all they are already coping with asciidoc and xmlto ;-)

We can continue shipping mozilla one to help the last group.

In the Makefile, we say:

    # Define NO_OPENSSL environment variable if you do not have OpenSSL.
    # This also implies MOZILLA_SHA1.

and with your change, we would start implying STANDALONE_OPENSSL_SHA1 instead. But if MOZILLA_SHA1 was given explicitly, we could use that.

If they really really really want the extra performance out of statically linked OpenSSL derivative, they could prepare a preprocessed assmebly on some other machine and use it as the last resort if they do not have/want Perl. The situation is exactly the same as the documentation set. They are using HTML/man prepared on another machine (namely, mine) as the last resort if they do not have/want AsciiDoc toolchain.