From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Torsten Bögershausen" <tboegi@web.de>,
larsxschneider@gmail.com, git@vger.kernel.org, jnareb@gmail.com,
mlbright@gmail.com, e@80x24.org
Subject: Re: [PATCH v4 11/12] convert: add filter.<driver>.process option
Date: Fri, 5 Aug 2016 18:27:10 -0400 [thread overview]
Message-ID: <20160805222710.chefh5kiktyzketh@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqfuqivpjv.fsf@gitster.mtv.corp.google.com>
On Fri, Aug 05, 2016 at 03:06:28PM -0700, Junio C Hamano wrote:
> Torsten Bögershausen <tboegi@web.de> writes:
>
> > On 2016-08-03 18.42, larsxschneider@gmail.com wrote:
> >> The filter is expected to respond with the result content in zero
> >> or more pkt-line packets and a flush packet at the end. Finally, a
> >> "result=success" packet is expected if everything went well.
> >> ------------------------
> >> packet: git< SMUDGED_CONTENT
> >> packet: git< 0000
> >> packet: git< result=success\n
> >> ------------------------
> > I would really send the diagnostics/return codes before the content.
>
> I smell the assumption "by the time the filter starts output, it
> must have finished everything and knows both size and the status".
>
> I'd prefer to have a protocol that allows us to do streaming I/O on
> both ends when possible, even if the initial version of the filters
> (and the code that sits on the Git side) hold everything in-core
> before starting to talk.
I think you really want to handle both cases:
- the server says "no, I can't fulfill your request" (e.g., HTTP 404)
- the server can abort an in-progress response to indicate that it
could not be fulfilled completely (in HTTP chunked encoding, this
requires hanging up before sending the final EOF chunk)
If we expect the second case to be rare, then hanging up before sending
the flush packet is probably OK. But we could also have a trailing error
code after the data to say "ignore that, we saw an error, but I can
still handle more requests".
It is true that you don't need the up-front status code in that case
(you can send an empty body and say "ignore that, we saw an error") but
that feels a little weird. And I expect it makes the lives of the client
easier to get a code up front, before it starts taking steps to handle
what it _thinks_ is probably a valid response.
-Peff
PS I haven't followed HTTP/2 development much, but I think it solves the
"hangup" issue by putting each request/response in its own framed
stream. I actually wonder if that is a direction we will want to go
eventually, too, or the same reason that HTTP/2 did: multiple async
requests across a single connection.
We already have some precedent in the sideband protocol. So imagine,
for example, that we could ask the filter to work on several files
simultaneously, by sending
git> \1[file1 content]
git> \2[file2 content]
git> \1[file1 content]
and so on. I don't think this is something that needs to happen in
the initial protocol (it's not like git can do parallel checkout
right now anyway). If there's a capability negotiation at the front
of the protocol, then an async feature can be worked out later. Just
food for thought at this point.
next prev parent reply other threads:[~2016-08-06 20:14 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20160727000605.49982-1-larsxschneider%40gmail.com/>
2016-07-29 23:37 ` [PATCH v3 00/10] Git filter protocol larsxschneider
2016-07-29 23:37 ` [PATCH v3 01/10] pkt-line: extract set_packet_header() larsxschneider
2016-07-30 10:30 ` Jakub Narębski
2016-08-01 11:33 ` Lars Schneider
2016-08-03 20:05 ` Jakub Narębski
2016-08-05 11:52 ` Lars Schneider
2016-07-29 23:37 ` [PATCH v3 02/10] pkt-line: add direct_packet_write() and direct_packet_write_data() larsxschneider
2016-07-30 10:49 ` Jakub Narębski
2016-08-01 12:00 ` Lars Schneider
2016-08-03 20:12 ` Jakub Narębski
2016-08-05 12:02 ` Lars Schneider
2016-07-29 23:37 ` [PATCH v3 03/10] pkt-line: add packet_flush_gentle() larsxschneider
2016-07-30 12:04 ` Jakub Narębski
2016-08-01 12:28 ` Lars Schneider
2016-07-31 20:36 ` Torstem Bögershausen
2016-07-31 21:45 ` Lars Schneider
2016-08-02 19:56 ` Torsten Bögershausen
2016-08-05 9:59 ` Lars Schneider
2016-07-29 23:37 ` [PATCH v3 04/10] pkt-line: call packet_trace() only if a packet is actually send larsxschneider
2016-07-30 12:29 ` Jakub Narębski
2016-08-01 12:18 ` Lars Schneider
2016-08-03 20:15 ` Jakub Narębski
2016-07-29 23:37 ` [PATCH v3 05/10] pack-protocol: fix maximum pkt-line size larsxschneider
2016-07-30 13:58 ` Jakub Narębski
2016-08-01 12:23 ` Lars Schneider
2016-07-29 23:37 ` [PATCH v3 06/10] run-command: add clean_on_exit_handler larsxschneider
2016-07-30 9:50 ` Johannes Sixt
2016-08-01 11:14 ` Lars Schneider
2016-08-02 5:53 ` Johannes Sixt
2016-08-02 7:41 ` Lars Schneider
2016-07-29 23:37 ` [PATCH v3 07/10] convert: quote filter names in error messages larsxschneider
2016-07-29 23:37 ` [PATCH v3 08/10] convert: modernize tests larsxschneider
2016-07-29 23:38 ` [PATCH v3 09/10] convert: generate large test files only once larsxschneider
2016-07-29 23:38 ` [PATCH v3 10/10] convert: add filter.<driver>.process option larsxschneider
2016-07-30 22:05 ` Jakub Narębski
2016-07-31 9:42 ` Jakub Narębski
2016-07-31 19:49 ` Lars Schneider
2016-07-31 22:59 ` Jakub Narębski
2016-08-01 13:32 ` Lars Schneider
2016-08-03 18:30 ` Designing the filter process protocol (was: Re: [PATCH v3 10/10] convert: add filter.<driver>.process option) Jakub Narębski
2016-08-05 10:32 ` Lars Schneider
2016-08-06 18:24 ` Lars Schneider
2016-08-03 22:47 ` [PATCH v3 10/10] convert: add filter.<driver>.process option Jakub Narębski
2016-07-31 22:19 ` Jakub Narębski
2016-08-01 17:55 ` Lars Schneider
2016-08-04 0:42 ` Jakub Narębski
2016-08-03 13:10 ` Lars Schneider
2016-08-04 10:18 ` Jakub Narębski
2016-08-05 13:20 ` Lars Schneider
2016-08-03 16:42 ` [PATCH v4 00/12] Git filter protocol larsxschneider
2016-08-03 16:42 ` [PATCH v4 01/12] pkt-line: extract set_packet_header() larsxschneider
2016-08-03 20:18 ` Junio C Hamano
2016-08-03 21:12 ` Jeff King
2016-08-03 21:27 ` Jeff King
2016-08-04 16:14 ` Junio C Hamano
2016-08-05 14:55 ` Lars Schneider
2016-08-05 16:31 ` Junio C Hamano
2016-08-05 17:31 ` Lars Schneider
2016-08-05 17:41 ` Junio C Hamano
2016-08-03 21:56 ` Lars Schneider
2016-08-03 16:42 ` [PATCH v4 02/12] pkt-line: add direct_packet_write() and direct_packet_write_data() larsxschneider
2016-08-03 16:42 ` [PATCH v4 03/12] pkt-line: add packet_flush_gentle() larsxschneider
2016-08-03 21:39 ` Jeff King
2016-08-03 22:56 ` [PATCH 0/7] minor trace fixes and cosmetic improvements Jeff King
2016-08-03 22:56 ` [PATCH 1/7] trace: handle NULL argument in trace_disable() Jeff King
2016-08-03 22:58 ` [PATCH 2/7] trace: stop using write_or_whine_pipe() Jeff King
2016-08-03 22:58 ` [PATCH 3/7] trace: use warning() for printing trace errors Jeff King
2016-08-04 20:41 ` Junio C Hamano
2016-08-04 21:21 ` Jeff King
2016-08-04 21:28 ` Junio C Hamano
2016-08-05 7:56 ` Jeff King
2016-08-05 7:59 ` Christian Couder
2016-08-05 18:41 ` Junio C Hamano
2016-08-03 23:00 ` [PATCH 4/7] trace: cosmetic fixes for error messages Jeff King
2016-08-04 20:42 ` Junio C Hamano
2016-08-05 8:00 ` Jeff King
2016-08-03 23:00 ` [PATCH 5/7] trace: correct variable name in write() error message Jeff King
2016-08-03 23:01 ` [PATCH 6/7] trace: disable key after write error Jeff King
2016-08-04 20:45 ` Junio C Hamano
2016-08-04 21:22 ` Jeff King
2016-08-05 7:58 ` Jeff King
2016-08-03 23:01 ` [PATCH 7/7] write_or_die: drop write_or_whine_pipe() Jeff King
2016-08-03 23:04 ` [PATCH 0/7] minor trace fixes and cosmetic improvements Jeff King
2016-08-04 16:16 ` [PATCH v4 03/12] pkt-line: add packet_flush_gentle() Junio C Hamano
2016-08-03 16:42 ` [PATCH v4 04/12] pkt-line: call packet_trace() only if a packet is actually send larsxschneider
2016-08-03 16:42 ` [PATCH v4 05/12] pkt-line: add functions to read/write flush terminated packet streams larsxschneider
2016-08-03 16:42 ` [PATCH v4 06/12] pack-protocol: fix maximum pkt-line size larsxschneider
2016-08-03 16:42 ` [PATCH v4 07/12] run-command: add clean_on_exit_handler larsxschneider
2016-08-03 21:24 ` Jeff King
2016-08-03 22:15 ` Lars Schneider
2016-08-03 22:53 ` Jeff King
2016-08-03 23:09 ` Lars Schneider
2016-08-03 23:15 ` Jeff King
2016-08-05 13:08 ` Lars Schneider
2016-08-05 21:19 ` Torsten Bögershausen
2016-08-05 21:50 ` Lars Schneider
2016-08-03 16:42 ` [PATCH v4 08/12] convert: quote filter names in error messages larsxschneider
2016-08-03 16:42 ` [PATCH v4 09/12] convert: modernize tests larsxschneider
2016-08-03 16:42 ` [PATCH v4 10/12] convert: generate large test files only once larsxschneider
2016-08-03 16:42 ` [PATCH v4 11/12] convert: add filter.<driver>.process option larsxschneider
2016-08-03 17:45 ` Junio C Hamano
2016-08-03 21:48 ` Lars Schneider
2016-08-03 22:46 ` Jeff King
2016-08-05 12:53 ` Lars Schneider
2016-08-03 20:29 ` Junio C Hamano
2016-08-03 21:37 ` Lars Schneider
2016-08-03 21:43 ` Junio C Hamano
2016-08-03 22:01 ` Lars Schneider
2016-08-05 21:34 ` Torsten Bögershausen
2016-08-05 21:49 ` Lars Schneider
2016-08-05 22:06 ` Junio C Hamano
2016-08-05 22:27 ` Jeff King [this message]
2016-08-06 11:55 ` Lars Schneider
2016-08-06 12:14 ` Jeff King
2016-08-06 18:19 ` Lars Schneider
2016-08-08 15:02 ` Jeff King
2016-08-08 16:21 ` Lars Schneider
2016-08-08 16:26 ` Jeff King
2016-08-06 20:40 ` Torsten Bögershausen
2016-08-03 16:42 ` [PATCH v4 12/12] convert: add filter.<driver>.process shutdown command option larsxschneider
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