Junio C Hamano <gitster@xxxxxxxxx> 于2020年9月16日周三 上午5:08写道：
>
> Han Xin <chiyutianyi@xxxxxxxxx> writes:
>
> > Atomic push may be rejected, which makes it meanigless to generate push
> > cert first. Therefore, the push cert generation was moved after atomic
> > check.
>
> The overstatement "may be rejected" is probably a bit misleading the
> readers and reviewers. REF_STATUS_REJECT_NONFASTFORWARD may be
> observed by check_to_send_update() but the reason is set in
> set_ref_status_for_push(), which locally decides not to propose a
> no-ff ref update to the other side. At this point of the control
> flow, the other side hasn't have a chance to reject the push,
> because "we want you to update these refs to these new values" is
> yet to be sent (it is done after composing the push certificate).
>
> We may decide not to push (e.g. their ref may not fast forward
> to what we are pushing) at this point in the code. Checking the
> condition first will save us to ask GPG to sign the push
> certificate, since we will not send it to the other side.
>
It's always hard for a new contributor to write a decent commit log message.
>
> > - if (!args->dry_run)
> > - advertise_shallow_grafts_buf(&req_buf);
>
> Why should this be moved? It doesn't seem to have anything to do
> with the push certificate.
>
Checking the condition first will also save us to prepare shallow advertise.
> > -
> > - if (!args->dry_run && push_cert_nonce)
> > - cmds_sent = generate_push_cert(&req_buf, remote_refs, args,
> > - cap_buf.buf, push_cert_nonce);
> > -
> > /*
> > * Clear the status for each ref and see if we need to send
> > * the pack data.
>
> This "Clear the status for each ref" worries me.
>
> The generate_push_cert() function RELIES on ref->status and filters
> out the ref that failed to pass the local check from the generated
> push certificate. If you let the loop (post context of this hunk)
> run, ref->status will be updated by it, so the net effect of this
> patch is that it breaks "non-atomic" case that pushes multiple refs
> and one of ref fails to pass the local check.
>
> IOW, generate_push_cert() MUST be called before this loop "clears
> the status for each ref" by assigning to ref->status.
>
The next block ("Finally, tell the other end!") is what we send
commands to "receive-pack", right after some of the status are reset
to REF_STATUS_OK or REF_STATUS_EXPECTING_REPORT by this chunk of code.
So moving the generate_push_cert() part right before the "Finally,
tell the other end!" part LGTM.
