"IMAP IDLE"-like long-polling "git fetch"

Hey all, I just added this to the TODO file for public-inbox[1] but
obviously it's intended for git.git (meta@public-inbox cc-ed):

+* Contribute something like IMAP IDLE for "git fetch".
+  Inboxes (and any git repos) can be kept up-to-date without
+  relying on polling.

I would've thought somebody had done this by now, but I guess
it's dependent on a bunch of things (TLS layer nowadays, maybe
HTTP/2), so git-daemon support alone wouldn't cut it...

Anyways, until this is implemented, feel free to continue
hammering a way on https://public-inbox.org/git/ with frequent
"git fetch".  I write C10K servers in my sleep -_-


[1] https://public-inbox.org/meta/20181229034342.11543-1-e@80x24.org/