Re: Request for detailed documentation of git pack protocol

From: Shawn O. Pearce <spearce@spearce.org>
Date: Jun 3, 2009, 20:24 UTC
Message-ID: <20090603202429.GO3355@spearce.org>
In-Reply-To: <200906032220.00238.jnareb@gmail.com>

Jakub Narebski <jnareb@gmail.com> wrote:

Show 5 quoted lines

> 
> >>> Oh, and send-pack/receive-pack protocol now has ".have" refs [...]
> 
> So the output (for fetch or clone) would look like this for repository
> with alternates (shared object database):

No.  fetch/clone (aka fetch-pack/upload-pack protocl) does not use
the .have feature.

> Does it matter for fetch, or is it important only for pushing?

Because yea, it only matters for pushing. Actually, in the case of fetch, we shouldn't advertise what our alternate has, the client should just fetch from the alternate.

In push it matters because the client wants to know what the remote
has, so it can trim the pack down to only the new objects, to reduce
transfer time.

> BTW. do "include-tag" capability MUST NOT (REQUIRED) be send if there
> are not tags (tag objects?), or just SHOULD NOT (RECOMMENDED), or even
> MAY NOT (OPTIONAL).  GitHub server doesn't send it if there are no 
> tags...

Clients MAY always send include-tag, hardcoding it into a request. The decision for a client to request include-tag only has to do with the client's desires for tag data, whether or not a server had advertised objects in the refs/tags/* namespace.

Clients SHOULD NOT send include-tag if remote.name.tagopt was set to --no-tags, as the client doesn't want tag data.

Servers MUST accept include-tag without error or warning, even if the server does not understand or support the option.

Servers SHOULD pack the tags if their referrant is packed and the client has requested include-tag.

Clients MUST be prepared for the case where a server has ignored include-tag and has not actually sent tags in the pack. In such cases the client SHOULD issue a subsequent fetch to acquire the tags that include-tag would have otherwise given the client.

-- 
Shawn.