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From: Lars Schneider <larsxschneider@gmail.com>
To: "Jakub Narębski" <jnareb@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
	gitster@pobox.com, tboegi@web.de, mlbright@gmail.com,
	remi.galan-alfonso@ensimag.grenoble-inp.fr, pclouds@gmail.com,
	e@80x24.org, ramsay@ramsayjones.plus.com, peff@peff.net
Subject: Re: [PATCH v2 0/5] Git filter protocol
Date: Thu, 28 Jul 2016 09:16:18 +0200	[thread overview]
Message-ID: <BFED7ED8-40DB-46B5-A1B7-4F49624D5A62@gmail.com> (raw)
In-Reply-To: <579906C5.1050809@gmail.com>


> On 27 Jul 2016, at 21:08, Jakub Narębski <jnareb@gmail.com> wrote:
> 
> W dniu 2016-07-27 o 02:06, larsxschneider@gmail.com pisze:
>> From: Lars Schneider <larsxschneider@gmail.com>
>> 
>> Hi,
>> 
>> thanks a lot for the extensive reviews. I tried to address all mentioned
>> concerns and summarized them below. The most prominent changes since v1 are
>> the following:
>> * Git offers a number of filter capabilities that a filter can request
>>  (right now only "smudge" and "clean" - in the future maybe "cleanFromFile",
>>  "smudgeToFile", and/or "stream")
>> * pipe communication uses a packet format (pkt-line) based protocol
> 
> I wonder if it would make sense to support both whole-file pipe communication,
> and packet format (pkt-line) pipe communication.
> 
> The problem with whole-file pipe communication (original proposal for
> new filter protocol is that it needs file size upfront.  For some types
> of filters it is not a problem:
> - if a filtered file has the same size as original, like for rot13
>   example in the test for the feature
> - if you can calculate the resulting file size from original size,
>   like for most if not all encryption formats (that includes GPG,
>   uudecode, base64, quoted-printable, hex, etc.); same for decryption,
>   and from converting between fixed-width encodings
> - if resulting file size is saved somewhere that is easy to get, like
>   for LFS solutions (I think).
> 
> For other filters it is serious problem.  For example indent, keyword
> expansion, rezipping with zero compression (well, maybe not this one,
> but at least the reverse of it), converting between encodings where
> at least one is variable width (like UTF-8),...
> 
> IMHO writing whole-file persistent filters is easier than using pkt-line.
> On the other hand using pkt-line allow for more detailed progress report.

I initially wanted to support only "while-file" pipe, too.

But Peff ($gmane/299902), Duy, and Eric, seemed to prefer the pkt-line
solution (gmane is down - otherwise I would have given you the links).

After I have looked at it I think the pkt-line solution is indeed nicer
for the following reasons:

(1) A stream optimized version (read/write in separate threads) of the filter
    protocol can be implemented in the future without changing the protocol
(2) pkt-line is a simple and easy to implement format
(3) Reuse of existing Git communication infrastructure
    -> code and documentation are less surprising to people that know Git
    -> you can use GIT_TRACE_PACKET to easily inspect the
       communication between Git and the filter process
(4) The overheads is neglect able (4 byte header vs 65516 byte content)


>> * a long running filter application is defined with "filter.<driver>.process"
> 
> I hope that won't confuse Git users into trying to use single-shot
> filters with a new protocol...

Yes, that was my intention for this new config.

Thanks,
Lars

  reply	other threads:[~2016-07-28  7:16 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-22 15:48 [PATCH v1 0/3] Git filter protocol larsxschneider
2016-07-22 15:48 ` [PATCH v1 1/3] convert: quote filter names in error messages larsxschneider
2016-07-22 15:48 ` [PATCH v1 2/3] convert: modernize tests larsxschneider
2016-07-26 15:18   ` Remi Galan Alfonso
2016-07-26 20:40     ` Junio C Hamano
2016-07-22 15:49 ` [PATCH v1 3/3] convert: add filter.<driver>.useProtocol option larsxschneider
2016-07-22 22:32   ` Torsten Bögershausen
2016-07-24 12:09     ` Lars Schneider
2016-07-22 23:19   ` Ramsay Jones
2016-07-22 23:28     ` Ramsay Jones
2016-07-24 17:16     ` Lars Schneider
2016-07-24 22:36       ` Ramsay Jones
2016-07-24 23:22         ` Jakub Narębski
2016-07-25 20:32           ` Lars Schneider
2016-07-26 10:58             ` Jakub Narębski
2016-07-25 20:24         ` Lars Schneider
2016-07-23  0:11   ` Jakub Narębski
2016-07-23  7:27     ` Eric Wong
2016-07-26 20:00       ` Jeff King
2016-07-24 18:36     ` Lars Schneider
2016-07-24 20:14       ` Jakub Narębski
2016-07-24 21:30         ` Jakub Narębski
2016-07-25 20:16           ` Lars Schneider
2016-07-26 12:24             ` Jakub Narębski
2016-07-25 20:09         ` Lars Schneider
2016-07-26 14:18           ` Jakub Narębski
2016-07-23  8:14   ` Eric Wong
2016-07-24 19:11     ` Lars Schneider
2016-07-25  7:27       ` Eric Wong
2016-07-25 15:48       ` Duy Nguyen
2016-07-22 21:39 ` [PATCH v1 0/3] Git filter protocol Junio C Hamano
2016-07-24 11:24   ` Lars Schneider
2016-07-26 20:11     ` Jeff King
2016-07-27  0:06 ` [PATCH v2 0/5] " larsxschneider
2016-07-27  0:06   ` [PATCH v2 1/5] convert: quote filter names in error messages larsxschneider
2016-07-27 20:01     ` Jakub Narębski
2016-07-28  8:23       ` Lars Schneider
2016-07-27  0:06   ` [PATCH v2 2/5] convert: modernize tests larsxschneider
2016-07-27  0:06   ` [PATCH v2 3/5] pkt-line: extract and use `set_packet_header` function larsxschneider
2016-07-27  0:20     ` Junio C Hamano
2016-07-27  9:13       ` Lars Schneider
2016-07-27 16:31         ` Junio C Hamano
2016-07-27  0:06   ` [PATCH v2 4/5] convert: generate large test files only once larsxschneider
2016-07-27  2:35     ` Torsten Bögershausen
2016-07-27 13:32       ` Jeff King
2016-07-27 16:50         ` Lars Schneider
2016-07-27  0:06   ` [PATCH v2 5/5] convert: add filter.<driver>.process option larsxschneider
2016-07-27  1:32     ` Jeff King
2016-07-27 17:31       ` Lars Schneider
2016-07-27 18:11         ` Jeff King
2016-07-28 12:10           ` Lars Schneider
2016-07-28 13:35             ` Jeff King
2016-07-27  9:41     ` Eric Wong
2016-07-29 10:38       ` Lars Schneider
2016-07-29 11:24         ` Jakub Narębski
2016-07-29 11:31           ` Lars Schneider
2016-08-05 18:55         ` Eric Wong
2016-08-05 23:26           ` Lars Schneider
2016-08-05 23:38             ` Eric Wong
2016-07-27 23:31     ` Jakub Narębski
2016-07-29  8:04       ` Lars Schneider
2016-07-29 17:35         ` Junio C Hamano
2016-07-29 23:11           ` Jakub Narębski
2016-07-29 23:44             ` Lars Schneider
2016-07-30  9:32               ` Jakub Narębski
2016-07-28 10:32     ` Torsten Bögershausen
2016-07-27 19:08   ` [PATCH v2 0/5] Git filter protocol Jakub Narębski
2016-07-28  7:16     ` Lars Schneider [this message]
2016-07-28 10:42       ` Jakub Narębski
2016-07-28 13:29       ` Jeff King
2016-07-29  7:40         ` Jakub Narębski
2016-07-29  8:14           ` Lars Schneider
2016-07-29 15:57             ` Jeff King
2016-07-29 16:20               ` Lars Schneider
2016-07-29 16:50                 ` Jeff King
2016-07-29 17:43                   ` Lars Schneider
2016-07-29 18:27                     ` Jeff King

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