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From: "Jakub Narębski" <jnareb@gmail.com>
To: Ramsay Jones <ramsay@ramsayjones.plus.com>,
	Lars Schneider <larsxschneider@gmail.com>
Cc: "Git Mailing List" <git@vger.kernel.org>,
	"Jeff King" <peff@peff.net>,
	"Torsten Bögershausen" <tboegi@web.de>,
	mlbright@gmail.com
Subject: Re: [PATCH v1 3/3] convert: add filter.<driver>.useProtocol option
Date: Mon, 25 Jul 2016 01:22:11 +0200	[thread overview]
Message-ID: <57954DA3.9090006@gmail.com> (raw)
In-Reply-To: <194ea810-76ff-f32c-0f8a-57e8e60b65f5@ramsayjones.plus.com>

W dniu 2016-07-25 o 00:36, Ramsay Jones pisze:
> On 24/07/16 18:16, Lars Schneider wrote:
>> On 23 Jul 2016, at 01:19, Ramsay Jones <ramsay@ramsayjones.plus.com> wrote:
>>> On 22/07/16 16:49, larsxschneider@gmail.com wrote:
[...]
>>>> This patch adds the filter.<driver>.useProtocol option which, if enabled,
>>>> keeps the external filter process running and processes all blobs with
>>>> the following protocol over stdin/stdout.
>>>>
>>>> 1. Git starts the filter on first usage and expects a welcome message
>>>> with protocol version number:
>>>> 	Git <-- Filter: "git-filter-protocol\n"
>>>> 	Git <-- Filter: "version 1"
>>>
>>> Hmm, I was a bit surprised to see a 'filter' talk first (but so long as the
>>> interaction is fully defined, I guess it doesn't matter).
>>
>> It was a conscious decision to have the `filter` talk first. My reasoning was:
>>
>> (1) I want a reliable way to distinguish the existing filter protocol ("single-shot 
>> invocation") from the new one ("long running"). I don't think there would be a
>> situation where the existing protocol would talk first. Therefore the users would
>> not accidentally mix them with a possibly half working, undetermined, outcome.
> 
> If an 'single-shot' filter were incorrectly configured, instead of a new one, then
> the interaction could last a little while - since it would result in deadlock! ;-)
> 
> [If Git talks first instead, configuring a 'single-shot' filter _may_ still result
> in a deadlock - depending on pipe size, etc.]

Would it be possible to do an equivalent of sending empty file to the filter?
If it is misconfigured old-style script, it would exit after possibly empty
output; if not, we would start new-style interaction.
 
This should be, if we agree that detecting misconfigured filters is a good
thing, tested.

>>
>> (2) In the future we could extend the pipe protocol (see $gmane/297994, it's very
>> interesting). A filter could check Git's version and then pick the most appropriate
>> filter protocol on startup.


  reply	other threads:[~2016-07-24 23:22 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 [this message]
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
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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