Johan, et. al.:
Solid discussion - thank you. As I said, I'll keep a watch as things
progress...
Cheers.
Doug
On Wed, May 10, 2017 at 5:37 PM, Johan Corveleyn <jcorvel_at_gmail.com> wrote:
> On Wed, May 10, 2017 at 5:40 PM, Doug Robinson
> <doug.robinson_at_wandisco.com> wrote:
> >
> > Johan:
> >
> > Sorry for my sporadic replies... bin a bit hectic here.
> >
> > Reply buried deep below.
> >
> > On Fri, May 5, 2017 at 5:09 AM, Johan Corveleyn <jcorvel_at_gmail.com>
> wrote:
> >>
> >> On Fri, May 5, 2017 at 12:49 AM, Doug Robinson
> >> <doug.robinson_at_wandisco.com> wrote:
> >> >
> >> > Johan:
> >> >
> >> > (sorry for the empty message - dwim failed)
> >> >
> >> > On Thu, May 4, 2017 at 7:26 AM, Johan Corveleyn <jcorvel_at_gmail.com>
> wrote:
> >> >>
> >> >> On Thu, May 4, 2017 at 10:16 AM, Daniel Shahaf <
> d.s_at_daniel.shahaf.name> wrote:
> >> >> > Doug Robinson wrote on Wed, May 03, 2017 at 15:54:50 -0400:
> >> >> ...
> >> >> >> Not seeing it - at least not yet. In Perl the RE needed to handle
> >> >> >> this would be one of the duals, e.g. "/trunk/iota(|/.*)" - the
> >> >> >> either/or with nothing on the left and "/.*" on the right. It
> really
> >> >> >> is a dual case. I know of no better syntax. Since we're working
> on
> >> >> >> this as a wildcard I don't see an alternative.
> >> >> >
> >> >> > Off the top of my head, we could have [/trunk/iota/***] and
> >> >> > [/trunk/iota/**] with different meanings (the former applies to
> >> >> > a /trunk/iota file, the latter doesn't). Does anyone else
> (besides Doug
> >> >> > and I) have ideas here?
> >> >>
> >> >> Hmm, /*** doesn't look like something I'd remember easily, if I
> wanted
> >> >> to use that feature as an svn admin.
> >> >>
> >> >> I have only followed this discussion from a distance. If I understand
> >> >> correctly the remaining point is whether or not /iota/** would match
> >> >> with the file /iota or not. Speaking purely from my own intuition, I
> >> >> would say "no". I feel this pattern is intended to apply to the
> >> >> _subtree_ below iota, including iota itself (which is thus implied to
> >> >> be a directory, because we're talking about subtrees). In practice I
> >> >> think the admin configuring this rule will know whether iota is ever
> >> >> intended to be a file or a directory. A rule like that to me always
> >> >> implies that "the guy who configured it" expects iota to be a
> >> >> directory (why else would he put a "subtree rule" for it).
> >> >>
> >> >> TBH, I also don't really see the use case of "I want this rule to
> >> >> apply to the _namespace_ iota, i.e. to the file iota (if it's a file)
> >> >> and to directory iota and its subtree (if it's a directory)". In
> >> >> context, you always know whether it's meant to be a file or a
> >> >> directory.
> >> >
> >> >
> >> > The use case is exactly that some administrator wants to reserve
> >> > the namespace. They do not want some sly person to create a file
> >> > where they will, at some point in the future, create a directory. It
> will
> >> > be sad that we can't have a simple way to make this reservation, but,
> >> > as I noted above, short of the current "[:glob:/iota/**]" doing the
> job it
> >> > will take 2 stanzas.
> >> >
> >> >>
> >> >> Maybe we should just follow what most other implementations do?
> >> >> I've done a quick check in Atlassian FishEye / Crucible (searching
> for
> >> >> files). There /iota/** does not match file /iota (but it does match
> >> >> directory /iota).
> >> >
> >> >
> >> > The FishEye reference I found does not have a "**" operator - just a
> "*"
> >> > operator (https://confluence.atlassian.com/jiracoreserver073/search-
> syntax-for-text-fields-861257223.html).
> >> >
> >> > For all cases where a tool has a "*" operator this is semantically
> going
> >> > to "not match" this use case since the "*" operator that has been
> >> > implemented in SVN (at least so far) does not span past a single
> >> > directory entry.
> >>
> >> Ah. No, I'm referring to this syntax in FishEye:
> >> https://confluence.atlassian.com/fisheye/pattern-matching-
> guide-298976797.html
> >>
> >> Unfortunately the document does not specify the cases we're interested
> >> in here. But I've tested them on our own FishEye instance :-). In this
> >> case "/dir/**" does return /dir, but "/file/**" does not return /file.
> >> But okay, it's just one example.
> >>
> >> In the FishEye doc they say they're doing their pattern mathing "same
> >> as the pattern matching in Apache Ant". So I've checked ant as well.
> >> On this page:
> >>
> >> https://ant.apache.org/manual/dirtasks.html#patterns
> >>
> >> at the bottom of the table they say:
> >> **/test/** - Matches all files that have a test element in their
> >> path, including test as a filename.
> >>
> >> So I've done a little test in ant (see [1]): apparently "**/test/**"
> >> will match the file test, but "/test/**" doesn't! Weird. Apparently
> >> the same goes for FishEye, if I put "**/" at the beginning of the
> >> pattern, it does match the file.
> >>
> >> Now, getting back to your use case: "reserving a namespace for future
> >> use" (i.e. for now we don't know whether "iota" will ever be a file or
> >> a directory, but in any case we don't want anyone to put anything
> >> there). To me it sounds like a very special use case. It seems to be
> >> something specific for authorization syntaxes, but much less
> >> applicable to searching existing filesystems (like glob patterns for
> >> shells or tools like FishEye). So maybe it's not such a good idea to
> >> look at those tools for inspiration anyway :-).
> >>
> >> Doug: do you think this is a common use case? Do other authorization
> >> systems offer this functionality in an easily configurable manner? I
> >> accept this is a valid use case, but it's not one that I would think
> >> of using (wearing my hat of svn admin) -- I focus on authorization of
> >> the existing files / directories.
> >
> >
> > It's a very common use case. Think of it in terms of allocating all
> release
> > branches to the release team. Or all Quality Assurance tags to the QA
> team.
>
> OK
>
> >>
> >> Come to think of it: if reserving a namespace for future use, and
> >> "/iota" doesn't exist yet, can't you just block the name "/iota"
> >> without glob pattern? It doesn't exist anyway, so if you'd like to
> >> create some subtree under it, you first have to create /iota, right?
> >
> >
> > There's 2 problems with this:
> >
> > 1. You're not trying to block the name "/iota", you're giving out privs
> to the
> > right team for creating (and nobody else).
> >
> > 2. The "**" operator is very special in that it does a "direct match" of
> all
> > at or below. That "direct match", in terms of wildcards, means that
> there
> > is no "recursing upwards" to find a parent rule. It's matched
> immediately.
> >
> > Consider multiple repositories in an organization (perhaps they have code
> > that cannot go to vendors with which they share some repos so they cannot
> > keep all of their projects within a single repo - or similar use case).
> A global
> > policy would have identical rules for all repositories. They can't know
> when
> > or if some subset of the repositories have the specific artifact or not.
> > It would be nice/handy/convenient if a single rule could do the
> reservation
> > rather than a pair.
>
> Okay, thanks for clarifying. It's all starting to make sense to me now :-).
>
> So the "reserve namespace" usecase is common and important, and it
> sounds very sensible to want to do this with a single rule. And the
> "**" matching is better at doing this than the "/iota" rule. Got it.
>
> >> Now, in the end, I don't want this issue to be blocked forever :-). I
> >> think in practice the confusion will be minimal, because either the
> >> administrator knows what kind of item "iota" is (a file or a
> >> directory), or the item doesn't exist yet and he'll be doing the
> >> "reserve namespace" use case. So for me it's fine if "/iota/**"
> >> effectively matches both the "directory iota and its subtree" and "the
> >> file iota". As long as it's documented that way then :-).
> >
> >
> > My document does that since that is the way that the branched
> > implementation for SVN 1.8 and 1.9 works today.
>
> Great.
>
> >> If Daniel insists, I'm fine with using "/***" as well, if we want to
> >> have this special "reserve namespace" meaning.
> >
> >
> > If so then we'll need to make sure to document the required changes to
> > our user's who are using the feature now. It's not a big deal but will
> be
> > critical when our users upgrade to SVN 1.10. So I'll continue to watch
> > this space carefully.
>
> As Daniel said, he doesn't insist :-) ... I misinterpreted that. And
> given that "/**" is already in use by your users as well as others
> that have already used the branched implementation
> (branches/authzperf), I see no reason to make things more difficult
> for little to no gain. So let's leave things like that.
>
> Thanks for your patience in discussing this.
>
> --
> Johan
>
--
*DOUGLAS B ROBINSON* SENIOR PRODUCT MANAGER
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*E* doug.robinson_at_wandisco.com
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Received on 2017-05-16 15:40:02 CEST