From: Thomas Rast <trast@student.ethz.ch>
Date: Tue, 14 Aug 2012 08:45:05 GMT
Subject: Re: [PATCH] rev-list docs: clarify --topo-order description
Message-ID: <877gt16ewe.fsf@thomas.inf.ethz.ch>
In-Reply-To: <7vsjbqbfhm.fsf@alter.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

>  --topo-order::
> -
> -	This option makes them appear in topological order (i.e.
> -	descendant commits are shown before their parents).
> +	This option makes them appear in topological order.  Even
> +	without this option, descendant commits are shown before
> +	their parents, but this tries to avoid showing commits on
> +	multiple lines of history intermixed.

I don't think that is true in general.  Without any -order options, we
process commits in date order, which *usually* means topological order,
but not always.  You can easily verify this:

  $ git init
  $ date
  Tue Aug 14 10:39:49 CEST 2012
  $ echo initial >file
  $ git add file
  $ GIT_COMMITTER_DATE="Tue Aug 14 11:39:49 2012" git commit
  $ echo foo >file
  $ git commit -mfoo file
  $ git checkout -bside HEAD^
  $ echo bar >file
  $ git commit -mbar file
  $ git log --all --oneline
  8c71325 bar
  e5072d7 initial
  1be702c foo

So the --topo-order switch *ensures* that we process commits in
topological order even in the face of skewed clocks.

I suspect that

> +	their parents, but this tries to avoid showing commits on
> +	multiple lines of history intermixed.

is just a fortunate side effect of the topological sort.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch