Re: [PATCH 1/5] http-protocol.txt: document SHA-256 "want"/"have" format

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 14, 2020, 20:47 UTC
Message-ID: <xmqqft8puf8d.fsf@gitster.c.googlers.com>
In-Reply-To: <xmqqo8ndufli.fsf@gitster.c.googlers.com>

Junio C Hamano <gitster@pobox.com> writes:

Show 19 quoted lines

> "brian m. carlson" <sandals@crustytoothpaste.net> writes:
>
>> On 2020-08-14 at 17:28:27, Junio C Hamano wrote:
>>> Martin Ågren <martin.agren@gmail.com> writes:
>>> 
>>> > Document that in SHA-1 repositories, we use SHA-1 for "want"s and
>>> > "have"s, and in SHA-256 repositories, we use SHA-256.
>>> 
>>> Ehh, doesn't this directly contradict the transition plan of "on the
>>> wire everything will use SHA-1 version for now?"
>>
>> SHA-256 repositories interoperate currently using SHA-256 object IDs.
>> It was originally intended that we wouldn't update the protocol, but
>> that leads to much of the testsuite failing since it's impossible to
>> move objects from one place to another.
>>
>> If we wanted to be more pedantically correct and optimize for the
>> future, we could say that the values use the format negotiated by the
>> "object-format" protocol extension and SHA-1 otherwise.

Yes, that's wonderful. I was confused when I said about the evolution path. We still would want to eventually do the on-the-fly migration over the wire to make SHA-1 and SHA-256 repositories interoperate, but at least we already can allow SHA-256 repositories safely attempt to talk to SHA-1 repositories and gracefully fail.

Thanks.