From: Junio C Hamano <gitster@pobox.com>
To: Jonathan Tan <jonathantanmy@google.com>
Cc: gitgitgadget@gmail.com, git@vger.kernel.org, stolee@gmail.com,
johannes.schindelin@gmx.de, lilinchao@oschina.cn
Subject: Re: [PATCH v4] builtin/clone.c: add --reject-shallow option
Date: Mon, 01 Mar 2021 14:34:23 -0800 [thread overview]
Message-ID: <xmqqh7lumrkg.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <20210301220319.3426185-1-jonathantanmy@google.com> (Jonathan Tan's message of "Mon, 1 Mar 2021 14:03:19 -0800")
Jonathan Tan <jonathantanmy@google.com> writes:
>> This may reject to clone from a shallow repository, but at this
>> point the bulk of the tranfer from the origin repository has already
>> happened, no? Rejecting after transferring many megabytes feels a
>> bit too late. That is one of the reasons why I kept hinting that
>> the transport layer needs to be taught an option to reject talking
>> to a shallow counterpart if we want to add this feature [*1*].
>
> Extending the transport layer in this way might not be too difficult in
> the case of native (SSH, git://) protocols and using protocol v0, since
> handshake() in transport.c (called indirectly from
> transport_get_remote_refs()) writes shallow information to a data
> structure that we could potentially expose for the caller to use (before
> it calls transport_fetch_refs(). I couldn't see how remote-using
> protocols (e.g. HTTP) communicate shallow information, though
> (remote-curl.c seems to just keep it for itself), so that will be a more
> difficult task. And of course there's the matter of protocol v2, which I
> discuss below.
>
>> [Footnote]
>>
>> *1* Looking at Documentation/technical/pack-protocol.txt, "git
>> fetch" seem to learn if the repository is shallow immediately
>> upon contacting "upload-pack" during the Reference Discovery
>> phase (we'd see 'shallow' packets if they are shallow). I
>> suspect that the right solution would be to teach the codepath
>> on the "git fetch" side that accepts, parses, and acts on this
>> packet to optionally stop communication and error out when the
>> caller asks not to talk with a shallow repository.
>
> This is true with protocol v0, but protocol v2 bundles all shallow
> information (whether coming from the fact that the remote is shallow or
> the fact that the fetcher specified --depth etc.) and sends them
> together with the packfile. It may be possible to stop packfile download
> (saving bandwidth on the client side, at least) once such information is
> returned, though.
So in short, the "we do not want to clone from a shallow upstream"
would not be possible to implement sensibly without significantly
cleaning up the protocol layers first, which makes the whole thing
pretty much moot.
Thanks for a review and insight.
next prev parent reply other threads:[~2021-03-02 11:59 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-04 3:31 [PATCH] builtin/clone.c: add --no-shallow option Li Linchao via GitGitGadget
2021-02-04 5:50 ` Junio C Hamano
2021-02-04 10:32 ` lilinchao
2021-02-04 18:36 ` Junio C Hamano
2021-02-04 14:00 ` Johannes Schindelin
2021-02-04 18:24 ` Junio C Hamano
2021-02-08 8:31 ` [PATCH v2 0/2] " Li Linchao via GitGitGadget
2021-02-08 8:31 ` [PATCH v2 1/2] " lilinchao via GitGitGadget
2021-02-08 8:31 ` [PATCH v2 2/2] builtin/clone.c: add --reject-shallow option lilinchao via GitGitGadget
2021-02-08 13:33 ` [PATCH v2 0/2] builtin/clone.c: add --no-shallow option Derrick Stolee
[not found] ` <32bb0d006a1211ebb94254a05087d89a835@gmail.com>
2021-02-08 13:48 ` lilinchao
2021-02-08 14:12 ` [PATCH v3] builtin/clone.c: add --reject-shallow option Li Linchao via GitGitGadget
2021-02-09 20:32 ` Junio C Hamano
[not found] ` <026bd8966b1611eb975aa4badb2c2b1190694@pobox.com>
2021-02-10 9:07 ` lilinchao
2021-02-10 16:27 ` Junio C Hamano
[not found] ` <eaa219a86bbc11ebb6c7a4badb2c2b1165032@pobox.com>
2021-02-20 10:40 ` lilinchao
2021-02-21 7:05 ` [PATCH v4] " Li Linchao via GitGitGadget
2021-02-22 18:12 ` Junio C Hamano
2021-03-01 22:03 ` Jonathan Tan
2021-03-01 22:34 ` Junio C Hamano [this message]
2021-03-02 8:44 ` lilinchao
2021-03-03 23:59 ` Junio C Hamano
2021-03-04 1:53 ` Jonathan Tan
[not found] ` <8f3c00de753911eb93d3d4ae5278bc1270191@pobox.com>
2021-02-28 17:58 ` lilinchao
2021-02-28 18:06 ` [PATCH v5] " Li Linchao via GitGitGadget
2021-03-01 7:11 ` lilinchao
2021-03-01 22:40 ` Johannes Schindelin
2021-03-04 6:26 ` lilinchao
2021-03-03 23:21 ` Junio C Hamano
2021-03-04 5:50 ` lilinchao
2021-03-04 17:19 ` [PATCH v6] " Li Linchao via GitGitGadget
2021-03-12 18:25 ` lilinchao
2021-03-25 11:09 ` [PATCH v7] " Li Linchao via GitGitGadget
2021-03-25 20:31 ` Junio C Hamano
2021-03-25 22:57 ` Junio C Hamano
[not found] ` <19c9dc128da911ebacc7d4ae5278bc1233465@pobox.com>
2021-03-26 3:34 ` lilinchao
[not found] ` <7a71c96c8dbd11eb8bb0d4ae5278bc1296681@pobox.com>
2021-03-26 3:49 ` lilinchao
2021-03-29 10:19 ` [PATCH v8] " Li Linchao via GitGitGadget
2021-03-29 21:36 ` Junio C Hamano
2021-03-30 9:54 ` Johannes Schindelin
2021-03-30 17:46 ` Junio C Hamano
2021-03-31 13:30 ` Johannes Schindelin
[not found] ` <f8b2582c913d11ebaddbd4ae5278bc1214940@gmx.de>
2021-03-31 11:03 ` lilinchao
2021-03-31 15:51 ` [PATCH v9] " lilinchao via GitGitGadget
2021-03-31 19:14 ` Junio C Hamano
2021-03-31 22:24 ` Johannes Schindelin
2021-03-31 22:37 ` Junio C Hamano
2021-04-01 10:46 ` [PATCH v10] " Li Linchao via GitGitGadget
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