Re: Thoughts on refactoring the transport (+helper) code

[Ilari Liusvaara <ilari.liusvaara@elisanet.fi>]

On Thu, Aug 13, 2015 at 11:42:50AM -0400, Dave Borowitz wrote:
> 
> In my ideal world:
> -smart_options would never be NULL, and would instead be called
> "options" with a "smart" bit which is unset for dumb protocols.
> -Command line option processing code in {fetch,clone,push}.c would set
> fields in options (formerly known as smart_options) rather than
> passing around string constants.
> -TRANS_OPT_* string constants would only be used for remote helper
> protocol option names, and no more hard-coding these names.
> -The flags arg to the push* callbacks would go away, and callbacks
> would respect options instead.
> -The helper code would not send options immediately, but instead send
> just the relevant options immediately before a particular command
> requires them. Hopefully we could then eliminate the set_option
> callback entirely. (Two things I ran into that complicated this: 1)
> backfill_tags mutates just a couple of options before reusing the
> transport, and 2) the handling of push_cas_option is very
> special-cased.)

AFAIK, here are what one can encounter with remote helpers:

Some remote helpers are always smart, some are always dumb, and some
may be smart or dumb, depending on the URL.

I don't know how useful the last one is (smart or dumb depending on
URL) is. I have never seen such remote helper (HTTP doesn't count,
from Git PoV it is always dumb).

All smart helpers take common options associated with git smart
transport (e.g. thin, follow tags, push certs, etc..).

Dumb transports may take some of these kind of of options (esp.
smart HTTP), but it is highly dependent on the helper.

Then transports can have connection-level options (e.g. HTTPS
cert options). These can be present regardless of wheither
transport is smart or dumb.

The receive-pack / send-pack paths fall into connection-level
options, even if those are presently in smart transport common
options. Since those things make sense for some smart transports
(e.g. ssh://), but not others (e.g. git://).


-Ilari