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From: Junio C Hamano <gitster@pobox.com>
To: Mike Hommey <mh@glandium.org>
Cc: git@vger.kernel.org
Subject: Re: suboptimal behavior of fast-import in some cases with "from"
Date: Mon, 06 Jul 2015 15:54:35 -0700	[thread overview]
Message-ID: <xmqq4mlgzyl0.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20150706220746.GA29367@glandium.org> (Mike Hommey's message of "Tue, 7 Jul 2015 07:07:46 +0900")

Mike Hommey <mh@glandium.org> writes:

> One of the first things parse_from does is unconditionally throw away
> the tree for the given branch, and then the "from" tree is loaded. So
> when the "from" commit is the current head of the branch, that make
> fast-import do more work than necessary.

If it is very common that the next commit the input stream wants to
create is often on top of the commit that was just created, and if
it is very common that the input stream producer knows what the
commit object name of the commit that was just created, then
optimising for that case does not sound too bad.  It really depends
on two factors:

 - How likely is it that other people make the same mistake?

 - How bad the damage to parse_from() would be if we wanted to
   optimize for this case?

  reply	other threads:[~2015-07-06 22:54 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-06 22:07 suboptimal behavior of fast-import in some cases with "from" Mike Hommey
2015-07-06 22:54 ` Junio C Hamano [this message]
2015-07-09  5:03   ` Mike Hommey
2015-07-09  5:52     ` Mike Hommey
2015-07-09  6:50       ` [PATCH] fast-import: Do less work when given "from" matches current branch head Mike Hommey
2015-07-09 20:37         ` Junio C Hamano
2015-07-09 22:30           ` Mike Hommey
2015-07-09 22:44             ` Junio C Hamano
2015-07-09 22:47               ` Junio C Hamano

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