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Re: svn's webdav not honouring partial GETs

From: C. Michael Pilato <cmpilato_at_collab.net>
Date: Tue, 30 Mar 2010 15:13:54 -0400

Greg Stein wrote:
> On Tue, Mar 30, 2010 at 12:36, C. Michael Pilato <cmpilato_at_collab.net> wrote:
>> Steve Simon wrote:
>>> Hi,
>>>
>>> Many appologies if this is not the correct place to ask about
>>> svn's dav support, if so please rediect me.
>>>
>>> AS per the subject, SVN's WebDAV server does not seem to
>>> be honouring partial HTTP GETs even though it appears to
>>> offer the facility with
>>>
>>> Accept-Range: bytes
>> [...]
>>
>>> Would you expect svn to support partial gets? Is SVN likely to support
>>> partial GETs in the future?
>> I wouldn't expect that support to exist today because Subversion's clients
>> don't require it (and that's really the driver for most of our server-side
>> features). Is it likely to grow that support in the future? Only if
>> someone writes the code. We've no reason to reject that enhancement, but
>> (again, because Subversion clients don't make use of the functionality) also
>> no compelling reason to prioritize it highly.
>
> Apache itself should be handling the ranged-GET operation. IOW, we
> shouldn't have to do anything. So maybe we broke Apache's range
> handling.

Apache doesn't pass along the range information to the content provider?
That seems rather inefficient, requiring that providers deliver the full
contents just so Apache can ignore some/most of them. Weird, but ultimately
off-topic here.

Glancing through the Apache sources, I'm guessing that byterange_filter.c is
the relevant code here. That filter has this comment:

    /* Don't attempt to do byte range work if this brigade doesn't
     * contain an EOS, or if any of the buckets has an unknown length;
     * this avoids the cases where it is expensive to perform
     * byteranging (i.e. may require arbitrary amounts of memory). */

I wonder if perhaps mod_dav_svn is creating naughty buckets?

-- 
C. Michael Pilato <cmpilato_at_collab.net>
CollabNet   <>   www.collab.net   <>   Distributed Development On Demand

Received on 2010-03-30 21:14:27 CEST

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