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[104.178.186.189]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6a15f1d6bf3sm144672276d6.105.2024.05.23.13.04.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 May 2024 13:04:17 -0700 (PDT) Date: Thu, 23 May 2024 16:04:15 -0400 From: Taylor Blau To: Jeff King Cc: git@vger.kernel.org, Elijah Newren , Patrick Steinhardt , Junio C Hamano Subject: Re: [PATCH v3 00/30] pack-bitmap: pseudo-merge reachability bitmaps Message-ID: References: <20240523110532.GA1326297@coredump.intra.peff.net> Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240523110532.GA1326297@coredump.intra.peff.net> On Thu, May 23, 2024 at 07:05:32AM -0400, Jeff King wrote: > I wonder if the start of the pseudo-merge section should have a 4-byte > version/flags field itself? I don't think that's something we've done > before, and maybe it's overkill. I dunno. It's just a lot easier to do > now than later. I think the tricky thing here would be that the extension itself is a variable size, so every version would have to put the "extension size" field in the same place. Otherwise, an older Git client which doesn't understand a future version of the pseudo-merge extension wouldn't know how large the extension is, and wouldn't be able to adjust the index_end field appropriately to skip over it. Of course, we could make it a convention that says "all versions have to place the extension size field at the same relative offset", but it feels weird to read some of the extension while not understanding the whole thing. I'm definitely not saying that I think the specification ought to be set in stone forever, but I think any changes would want to be behind a new bitmap extension, not a version within the same extension. Thanks, Taylor