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From Greg Stein <gst...@gmail.com>
Subject Re: Why do we check the base checksum so often?
Date Mon, 06 Feb 2012 23:28:16 GMT
Well, sure. It will still be correct because our Ev2-aware libraries
will not use Ev1 APIs, and (thus) never have shims inserted. But I
think that "third-party" helps to clarify who we're talking about:
developers/products that are not part of the core svn releases. In any
case, we're just talking about my emails. Not product API
documentation. I like the extra qualification.

Cheers,
-g

On Mon, Feb 6, 2012 at 18:15, Daniel Shahaf <danielsh@elego.de> wrote:
> I get your distinction between "clients that use the native Ev2 API",
> "clients that use the Ev1 API in Ev2-aware libraries", and "clients that
> use the Ev1 API in Ev2-oblivious libraries".
>
> But I think striking the word(s) "third-party" from your third paragraph
> will not affect its correctness.
>
> Greg Stein wrote on Mon, Feb 06, 2012 at 17:55:29 -0500:
>> On Mon, Feb 6, 2012 at 17:39, Daniel Shahaf <danielsh@elego.de> wrote:
>> >...
>> > 1. Third-parties who use Ev1 interface would lose the integrity check.
>> >
>> > 2. Subversion 1.7 uses, and will use, Ev1 interfaces.
>> >
>> > Therefore:
>> >
>> > 3. Subversion 1.7 would lose the integrity check.
>> >
>> > Correct?
>>
>> Nope. 'svn' is not considered a third-party, to begin with. Further,
>> internally, it only uses the Ev1 interfaces. No shims get inserted.
>> When we deploy Ev2 within the svn libraries and tools (in the 1.8 or
>> 1.9 release), we aren't going to use the shims, so we aren't going to
>> lose the integrity check.
>>
>> Third party clients, linked to Ev2-using libraries, and which continue
>> to use the old Ev1 APIs will have a shim inserted, and (thus) lose the
>> base_checksum integrity check.
>>
>> IOW, when we release an Ev2-based Subversion, and third-party clients
>> that were built against the 1.0 through 1.7 APIs... those clients will
>> have shims inserted, and lose the check. It *is* possible that our
>> backwards-compat code could fetch the checksum and pass it along to
>> those third-party Ev1 users. But in the current dual-shim setup that
>> Hyrum is developing/testing with, there is no such mechanism for
>> fetching (hard to do, compared to just disabling the check in the
>> first place).
>>
>> Does that make sense?
>>
>> Cheers,
>> -g

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