Re: [PATCH 2/3] exclude: do strcmp as much as possible before fnmatch

> Actually I was referring to the exclude_stack.
>
> Suppose you have .gitignore file at the top that lists /foo/bar/*.c
> (among other millions of patterns anchored to specific directory),
> and another in the foo/bar directory.  When you are looking at a
> path in the top-level, currently the exclude_stack would have one
> element, per-directory one for .gitignore at the top, that has
> millions of patterns that would never match.  And then when you
> descend into foo/bar directory, prep_exclude would link two elements
> (one for foo/ directory which may be empty, another for foo/bar
> directory) to this, and then you check paths you see in foo/bar
> directory using all the elements that appear in the exclude_stack.
>
> What I was suggesting was that you could choose not to add
> /foo/bar/*.c entry in the exclude_stack element for the top-level
> (but remember you did so), and then inside prep_exclude() when you
> look at different directory, e.g. foo/bar, notice that higher level
> (i.e. toplevel in this example) has such a deferred patterns that
> applies to the new directory.  Then instead of adding /foo/bar/*.c
> at the top-level, you can pretend as if /*.c appeared in .gitignore
> file in the deeper level in the hierarchy.
>
> And this does not happen per path you check; exclude_stack used by
> excluded() is designed to take advantage of the access pattern that
> we tend to check paths from the same directory together, so such an
> adjustment will be per directory switching (i.e. it will be part of
> the prep_exclude() overhead that is amortized over paths you walk).