knit performance 1

[Johan Rydberg]

Robert Collins <robertc at robertcollins.net> writes:

> This is a knit performance improvement patch:
>      def _add(self, version_id, lines, parents, delta):
>          """Add a set of lines on top of version specified by parents.
>  
>          If delta is true, compress the text as a line-delta against
>          the first parent.
> +
> +        Any versions not present will be converted into ghosts.
>          """
> -        if delta and not parents:
> +        ghostless_parents = []
> +        ghosts = []
> +        for parent in parents:
> +            if not self.has_version(parent):
> +                ghosts.append(parent)
> +            else:
> +                ghostless_parents.append(parent)
> +
> +        if delta and not len(ghostless_parents):

Why call it ghostless_parents and not present_parents? 

Otherwise +1.

~j