Re: [PATCH] http-protocol.txt: add missing flush to example
- From
Jeff King <peff@peff.net>
- Date
- Nov 18, 2021, 16:38 UTC
- Message-ID
- <YZaBnlUWDiid3Pc3@coredump.intra.peff.net>
- In-Reply-To
- <pull.1141.git.git.1637234203401.gitgitgadget@gmail.com>
On Thu, Nov 18, 2021 at 11:16:43AM +0000, TimTIM via GitGitGadget wrote:
Show 7 quoted lines
> From: TimTim Wong <t2@live.hk> > > Signed-off-by: Timothy Wong <i@timtim.hk> > --- > Fix example in documentation > > wants must be flushed with 0000 before haves
This explanation would probably make more sense in the commit message.
I think this is only true for the v0 protocol. In the v2 protocol, we take all of the wants/haves as a single sequence. That may be OK for our purposes here, though. While the v2 docs do refer to http-protocol.txt, it is only for the "Initial Client Request" section. The actual v2 fetch primitive is defined separately in protocol-v2.txt.
Show 12 quoted lines
> diff --git a/Documentation/technical/http-protocol.txt b/Documentation/technical/http-protocol.txt > index cc5126cfeda..facb315a993 100644 > --- a/Documentation/technical/http-protocol.txt > +++ b/Documentation/technical/http-protocol.txt > @@ -314,8 +314,9 @@ Clients MUST first perform ref discovery with > C: Content-Type: application/x-git-upload-pack-request > C: > C: 0032want 0a53e9ddeaddad63ad106860237bbf53411d11a7\n > - C: 0032have 441b40d833fdfa93eb2908e52742248faf0ee993\n > C: 0000 > + C: 0032have 441b40d833fdfa93eb2908e52742248faf0ee993\n > + C: done
OK, so the "have" lines moves after the flush, which makes sense. There's no longer a trailing flush, though. Instead, we put in a "done" command. This is OK, and what we'd often send in practice, but it is optional (due to "no-done"). I wonder if it is worth keeping things simpler. I dunno.
(BTW, if you run with GIT_TRACE_PACKET here, it's a bit misleading. We _do_ send a flush after the "done", but it's the flush to tell remote-curl that it should send the stateless-rpc packet; it doesn't actually go over the wire with the HTTP request).
Show 10 quoted lines
> @@ -337,9 +338,9 @@ server advertises capability `allow-tip-sha1-in-want` or > `allow-reachable-sha1-in-want`. > > compute_request = want_list > + "0000" > have_list > - request_end > - request_end = "0000" / "done" > + "done" >
OK, so here we put the flush after want_list, which is good. But this loses the optionality of "done". I think it's valid to just send the flush, but this BNF no longer reflects that. Or if I'm wrong, I think this needs to be discussed in the commit message.
I wondered if the non-http protocol had a similar problem, but it treats the "want" and "have" phases more independently. E.g., we get:
upload-request = want-list
*shallow-line
*1depth-request
[filter-request]
flush-pktand then later:
upload-haves = have-list
compute-end
compute-end = flush-pkt / PKT-LINE("done")which is OK.
-Peff