Re: [PATCH v12 3/7] receive-pack: add new proc-receive hook

> Thanks to Peff for providing technical details of the architecture.  I
> understand that "receive-pack" of GitHub backend is not involved in
> references update (executing the commands), so the "proc-receive" hook
> won't be turned on for GitHub's architecture. While in our
> architecture (inspired by "spokes" of GitHub), the proxy will deliver
> not only packfile, but also commands to all three replicas. The proxy
> will execute "receive-pack" on the replica with a special argument, so
> the proxy can talk with "receive-pack" with an extended protocol.
> After running pre-receive hook and release the packfile from
> quarantine, the replica will stop and wait for the proxy to
> coordinate. After creating a distributed lock, the proxy will tell all
> the replicas continue to update the references.  One problem we met is
> the proc-receive and the post-receive hook must be executed once. We
> can make the execution of the hooks idempotent, or let only one of the
> replica run the hook. We choose the latter.

> I agree that adding new capability (report-status-v2) is a better
> solution, but I think the above extension is a bit wordy. We add
> additional 18 characters for each "ok <ref>" status, and add
> additional 32 characters for each "ng <ref> <msg>" status. Can we
> extend it like this:
> 
>     ok <ref>
>     [optional key-value pairs]
>     ng <ref> <error message>
>     [optional key-value pairs]