From: Junio C Hamano <gitster@pobox.com>
To: Brandon Williams <bmwill@google.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 2/2 v2] ls-files: add pathspec matching for submodules
Date: Fri, 23 Sep 2016 11:48:18 -0700 [thread overview]
Message-ID: <xmqqfuoq1mh9.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <1474500486-101640-1-git-send-email-bmwill@google.com> (Brandon Williams's message of "Wed, 21 Sep 2016 16:28:06 -0700")
Brandon Williams <bmwill@google.com> writes:
> - /* Find common prefix for all pathspec's */
> - max_prefix = common_prefix(&pathspec);
> + /*
> + * Find common prefix for all pathspec's
> + * This is used as a performance optimization which unfortunately cannot
> + * be done when recursing into submodules
> + */
> + if (recurse_submodules)
> + max_prefix = NULL;
> + else
> + max_prefix = common_prefix(&pathspec);
> max_prefix_len = max_prefix ? strlen(max_prefix) : 0;
This is OK for now, but for a future enhancement, I think we could
do better than this. In a superproject with a submodule at "sub/",
the current implementation of the common_prefix() helper would yield
"sub/a/" when given "sub/a/x" and "sub/a/y" (a pathspec with two
elements), which we want to avoid.
But somebody should be able to notice, before "sub/a/" is given to
max_prefix here, that "sub/" is the leaf level in our repository and
reduce the max_prefix to it. dir.c::common_prefix_len() might be
a place we could do so, but I didn't think about the ramifications
of doing so for other callers of common_prefix() or when we are not
recursing into submodules. Doing it in the caller here, i.e.
max_prefix = common_prefix(&pathspec);
if (recurse_submodules)
max_prefix = chomp_at_submodule_boundary(max_prefix);
is certainly safer.
If the superproject has submodules at "a/b/{sub1,sub2,...}", this
matters more. We do want to notice that we won't have to scan
outside "a/b/" of the index given "a/b/sub1" and "a/b/sub2" as a
pathspec.
The common_prefix_len() function also looks beyond symbolic links,
which is another thing that we may want to think about. In a
repository with a symbolic link "link" pointing somewhere else, when
you give "link/a/x" and "link/a/y" (a pathspec with two elements),
we would get "link/a/" as a common prefix, but we won't find
anything underneath "link" in our index. In such a case, leaving
the common prefix to "link/a/" _might_ allow us to notice that no
pathspec elements can ever match, so not noticing that the common
prefix points beyond a symbolic link might be a feature. I dunno.
next prev parent reply other threads:[~2016-09-23 18:48 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-21 22:04 [PATCH 1/2] ls-files: adding support for submodules Brandon Williams
2016-09-21 22:04 ` [PATCH 2/2] ls-files: add pathspec matching " Brandon Williams
2016-09-21 22:53 ` Junio C Hamano
2016-09-21 23:23 ` Brandon Williams
2016-09-21 23:28 ` [PATCH 2/2 v2] " Brandon Williams
2016-09-23 18:48 ` Junio C Hamano [this message]
2016-09-23 19:20 ` Junio C Hamano
2016-09-23 20:49 ` Brandon Williams
2016-09-21 22:08 ` [PATCH 1/2] ls-files: adding support " Brandon Williams
2016-09-21 22:28 ` Junio C Hamano
2016-09-21 22:38 ` Brandon Williams
2016-09-21 22:42 ` [PATCH 1/2] ls-files: optionally recurse into submodules Brandon Williams
2016-09-22 6:20 ` Jeff King
2016-09-23 23:31 ` Brandon Williams
2016-09-21 23:13 ` [PATCH 1/2] ls-files: adding support for submodules Junio C Hamano
2016-09-22 4:18 ` Jeff King
2016-09-22 16:04 ` Stefan Beller
2016-09-22 18:13 ` Junio C Hamano
2016-09-23 3:41 ` Jeff King
2016-09-23 5:47 ` Stefan Beller
2016-09-23 6:06 ` Jeff King
2016-09-23 16:16 ` Brandon Williams
2016-09-23 16:34 ` Stefan Beller
2016-09-25 11:03 ` Nazri Ramliy
2016-09-27 21:38 ` Junio C Hamano
2016-09-27 21:48 ` Brandon Williams
2016-09-27 22:01 ` Junio C Hamano
2016-09-27 22:09 ` Brandon Williams
2016-09-27 22:23 ` Junio C Hamano
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