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Re: svn commit: r1548823 - in /subversion/trunk/subversion/libsvn_fs_x: dag.c id.c id.h temp_serializer.c temp_serializer.h

From: Branko Čibej <brane_at_wandisco.com>
Date: Sun, 22 Dec 2013 14:46:50 +0100

On 22.12.2013 13:54, Stefan Fuhrmann wrote:
> [Back from enjoying the plague]
> On Sun, Dec 8, 2013 at 4:53 PM, Branko Čibej <brane_at_wandisco.com
> <mailto:brane_at_wandisco.com>> wrote:
> On 08.12.2013 11:52, Stefan Fuhrmann wrote:
>> On Sun, Dec 8, 2013 at 11:27 AM, Daniel Shahaf
>> <d.s_at_daniel.shahaf.name <mailto:d.s_at_daniel.shahaf.name>> wrote:
>> Stefan Fuhrmann wrote on Sun, Dec 08, 2013 at 11:09:47 +0100:> >
>> >
>> > Duly noted for Subversion 2.0
>> >
>> > For now, however, we have to implement id_vtable_t.
>> Huh? id_vtable_t is not a public API. I assume the id
>> vtable falls
>> under the same rules as the fs_library vtable --- see
>> fs_library_vtable_t.get_version's docstring.
>> True, but the following API simply don't provide any more
>> information:
>> svn_fs_check_related(const svn_fs_id_t *a, const svn_fs_id_t *b)
>> svn_fs_compare_ids(const svn_fs_id_t *a, const svn_fs_id_t *b)
>> So, our private vtable depends on the data provided by public API.
>> Adding the pool member to the internal struct is exactly the way to
>> decouple the implementation from the existing public interface.
> There's nothing wrong with revising the public API to require a
> scratch pool. Sure, the deprecated, pool-less version will be less
> efficient. But I've yet to hear why "lean and smart", i.e.,
> unstructured IDs are so much better. than what we have currently.
> After all, their structure matches the semantics of our repository
> model, regardless of implementation.
> This is not about structured vs. unstructured IDs. It's about needlessly
> exposing internal representation at the API level. For instance, it
> requires
> us to never change the internal node_id assignment rules (copy vs.
> branch):
> svn_fs_compare_ids does not provide a pool argument; hence the ID struct
> needs to always carry all information.

I'll just point out that the API does not dictate what kind of IDs you
use internally in the implementation. The fact that svn_fs_id_t exists
does not mean you have to use its fixed-size, binary representation in
directory reps, or anywhere else in the storage layer.

So I wonder who's confusing API with implementation now.

-- Brane

Branko Čibej | Director of Subversion
WANdisco // Non-Stop Data
e. brane_at_wandisco.com
Received on 2013-12-22 14:50:49 CET

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