Re: [PATCH] graph: Fix log's graph's colors when merging branches.

From: John Keeping <john@keeping.me.uk>
Date: Oct 17, 2013, 08:13 UTC
Message-ID: <20131017081336.GS27238@serenity.lan>
In-Reply-To: <20131017064853.GA7419@duunidell>

On Thu, Oct 17, 2013 at 09:52:09AM +0300, Hemmo Nieminen wrote:

Show 14 quoted lines

> The log's graph's colors were off sometimes when merging several
> branches. For example in the graph depicted below, the '-----.' part
> following the asterisk was colored with incorrect colors. This was
> caused by the fact that the leftmost branches, not part of the merge,
> were not taken into account when calculating the column numbers
> (colors).
> 
>   | |     Merge of http://members.cox.net/junkio/git-jc.git
>   | |
>   | *-----.   commit 211232bae64bcc60bbf5d1b5e5b2344c22ed767e
>   | |\ \ \ \  Merge: fc54a9c 9e30dd7 c4b83e6 6602659 b28858b
>   | | | | | | Author: Junio C Hamano <junkio@cox.net>
> 
> Signed-off-by: Hemmo Nieminen <hemmo.nieminen@iki.fi>

It took me a minute to spot the problem when I tested this, but you're right that there is a bug and I agree that the patch below is the right fix.

Perhaps a better commit message will help others looking at this, maybe something like this?

    graph: fix coloring around octopus merges

    When drawing the graph of an octopus merge, we draw a horizontal
    line from parents 3 and above into the asterisk representing the
    commit.  The sections of this line should be colored to match the
    graph lines coming in from above.

    However, if the commit is not in the left-most column we do not take
    into account the columns to the left of the commit when calculating
    these colors.  Fix this by adding the appropriate offset to the
    column index used for calculating the color.
    ---

    Commit 211232b (Octopus merge of the following five patches.,
    2005-05-05) in git.git's history exhibits this problem.

The section below the "---" does not become part of the commit message, when the patch is added to Git, but is used for notes that might help reviewers.

Show 21 quoted lines

> ---
>  graph.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/graph.c b/graph.c
> index b24d04c..6404331 100644
> --- a/graph.c
> +++ b/graph.c
> @@ -801,10 +801,10 @@ static int graph_draw_octopus_merge(struct git_graph *graph,
>  	int num_dashes =
>  		((graph->num_parents - dashless_commits) * 2) - 1;
>  	for (i = 0; i < num_dashes; i++) {
> -		col_num = (i / 2) + dashless_commits;
> +		col_num = (i / 2) + dashless_commits + graph->commit_index;
>  		strbuf_write_column(sb, &graph->new_columns[col_num], '-');
>  	}
> -	col_num = (i / 2) + dashless_commits;
> +	col_num = (i / 2) + dashless_commits + graph->commit_index;
>  	strbuf_write_column(sb, &graph->new_columns[col_num], '.');
>  	return num_dashes + 1;
>  }