On Wed, Jun 13, 2018 at 05:13:02PM -0400, Jeff King wrote: > On Tue, Jun 12, 2018 at 06:54:17PM +0000, Kirill Smelkov wrote: > > > > If an extra connection isn't a problem, you might be better off with > > > "git ls-remote", and then picking through the results for refs of > > > interest, and then "git fetch-pack" to actually get the pack. That's how > > > git-fetch worked when it was a shell script (e.g., see c3a200120d, the > > > last shell version). > > > > Yes, this is what I ended up doing: > > > > https://lab.nexedi.com/kirr/git-backup/commit/899103bf > > > > but for another reason - to avoid repeating for every fetched repository > > slow (in case of my "big" destination backup repository) quickfetch() > > checking in every spawned `git fetch`: git-backup can build index of > > objects we already have ourselves only once at startup, and then in > > fetch, after checking lsremote output, consult that index, and if we see > > we already have everything for an advertised reference - just avoid > > giving it to fetch-pack to process. It turns out for many pulled > > repositories there is usually no references changed at all and this way > > fetch-pack can be skipped completely: > > > > https://lab.nexedi.com/kirr/git-backup/commit/3efed898 > > Thanks for sharing that, it's an interesting case. I'd hope that > git-fetch is smart enough not to even bother with quickfetch() if there > are no refs to update. But if we have even one change to fetch, then > yeah, in the general case it makes sense to me that you could do better > by amortizing the scan of local objects across many operations.
Thanks for feedback. For the reference in case of git-backup `git fetch` or `git fetch-pack` would have to always do quickfetch scan or equivalent, because in case of backup repo there is only one reference in it - its master - and references of backed up repositories do not have anything representing them in backup.git/refs/ . Kirill
