From: Lars Schneider <larsxschneider@gmail.com>
To: Eric Wong <e@80x24.org>
Cc: git@vger.kernel.org
Subject: Re: RFC: Enable delayed responses to Git clean/smudge filter requests
Date: Tue, 15 Nov 2016 15:29:09 +0100 [thread overview]
Message-ID: <5BC69AC1-5499-4F73-816A-D8786106D796@gmail.com> (raw)
In-Reply-To: <20161115010356.GA29602@starla>
> On 15 Nov 2016, at 02:03, Eric Wong <e@80x24.org> wrote:
>
> Lars Schneider <larsxschneider@gmail.com> wrote:
>> Hi,
>>
>> Git always performs a clean/smudge filter on files in sequential order.
>> Sometimes a filter operation can take a noticeable amount of time.
>> This blocks the entire Git process.
>
> I have the same problem in many places which aren't git :>
>
>> I would like to give a filter process the possibility to answer Git with
>> "I got your request, I am processing it, ask me for the result later!".
>>
>> I see the following way to realize this:
>>
>> In unpack-trees.c:check_updates() [1] we loop through the cache
>> entries and "ask me later" could be an acceptable return value of the
>> checkout_entry() call. The loop could run until all entries returned
>> success or error.
>>
>> The filter machinery is triggered in various other places in Git and
>> all places that want to support "ask me later" would need to be patched
>> accordingly.
>
> That all sounds reasonable.
>
> The filter itself would need to be aware of parallelism
> if it lives for multiple objects, right?
Correct. This way Git doesn't need to deal with threading...
>> Do you think this could be a viable approach?
>
> It'd probably require a bit of work, but yes, I think it's viable.
>
> We already do this with curl_multi requests for parallel
> fetching from dumb HTTP servers, but that's driven by curl
> internals operating with a select/poll loop.
>
> Perhaps the curl API could be a good example for doing this.
Thanks for the pointer!
>> Do you see a better way?
>
> Nope, I prefer non-blocking state machines to threads for
> debuggability and determinism.
Agreed!
> Anyways, I'll plan on doing something similar (in Perl) with the
> synchronous parts of public-inbox which relies on "cat-file --batch"
> at some point... (my rotational disks are sloooooooow :<)
That sounds interesting! What changes to you have in mind for
"cat-file --batch"? We are thinking about performance improvements
in that area, too. I would be happy to help reviewing your patches!
Thanks a lot for your RFC feedback,
Lars
next prev parent reply other threads:[~2016-11-15 14:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-14 21:09 RFC: Enable delayed responses to Git clean/smudge filter requests Lars Schneider
2016-11-15 1:03 ` Eric Wong
2016-11-15 14:29 ` Lars Schneider [this message]
2016-11-15 18:03 ` Junio C Hamano
2016-11-16 9:53 ` Lars Schneider
2016-11-16 18:15 ` Junio C Hamano
2016-11-16 18:47 ` Lars Schneider
2016-11-16 19:19 ` Junio C Hamano
2016-11-16 22:41 ` Jakub Narębski
2016-11-16 23:46 ` Junio C Hamano
2016-11-17 9:19 ` Lars Schneider
2016-11-24 15:45 ` Lars Schneider
2016-11-28 21:48 ` Junio C Hamano
2016-11-15 18:27 ` Eric Wong
2017-01-09 20:44 ` Stefan Beller
2017-01-11 12:57 ` Lars Schneider
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