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Re: [PATCH] HTTPv2 allow client to control transaction name in protocol

From: Philip Martin <philip.martin_at_wandisco.com>
Date: Tue, 01 Mar 2011 16:50:40 +0000

"C. Michael Pilato" <cmpilato_at_collab.net> writes:

> On 03/01/2011 10:09 AM, Philip Martin wrote:
>> Index: subversion/mod_dav_svn/dav_svn.h
>> ===================================================================
>> --- subversion/mod_dav_svn/dav_svn.h (revision 1075718)
>> +++ subversion/mod_dav_svn/dav_svn.h (working copy)
>> @@ -52,6 +52,9 @@
>> /* a pool-key for the shared dav_svn_root used by autoversioning */
>> #define DAV_SVN__AUTOVERSIONING_ACTIVITY "svn-autoversioning-activity"
>>
>> +/* used to distinguish client supplied TXN-NAME from FS supplied, this
>> + is a string that is NEVER the start of an FS transaction name */
>> +#define DAV_SVN__VISIBLE_TXN_PREFIX "$"
>
> Whoops! Technically, mod_dav_svn hasn't access to the knowledge required to
> make this assertion. Who says a transaction's name can't start with a
> dollar sign?

I suppose I should make the comment more accurate. The prefix
determines whether the visible:internal mapping will apply. If a
internal transaction's name starts with the prefix then an identity
mapping will get applied. That still works but the overhead of going
through the activity database makes it marginally less efficient.

> I'm still at odds with myself about this patch in general. HTTPv2 offers us
> a chance to clean up and simplify our protocol, and before it even sees its
> first release you want to add a bit of obfuscation and indirection required
> solely by one commercial product? Come on. (If you know me at all, you
> realize my antagonism is aimed not at said product, but at the proposed
> protocol hack.) So I'm trying to convince myself that there's some general
> utility to this change -- that somewhere, sometime, somebody else will thank
> us for adding it.

There is a demand for WANdisco's replicator. It may be the only product
at the moment but it's possible that somebody will write an open source
product that also does multiplexing and/or replay. They will then face
the same problem that WANdisco does now.

-- 
Philip
Received on 2011-03-01 17:51:20 CET

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