Jonathan Tan <jonathantanmy@xxxxxxxxxx> writes: > When fetching into a repository, a connectivity check is first made by > check_exist_and_connected() in builtin/fetch.c that runs: > > git rev-list --objects --stdin --not --all --quiet <(list of objects) > > If the client repository has many refs, this command can be slow, > regardless of the nature of the server repository or what is being > fetched. A profiler reveals that most of the time is spent in > setup_revisions() (approx. 60/63), and of the time spent in > setup_revisions(), most of it is spent in parse_object() (approx. > 49/60). This is because setup_revisions() parses the target of every ref > (from "--all"), and parse_object() reads the buffer of the object. > > Reading the buffer is unnecessary if the repository has a commit graph > and if the ref points to a commit (which is typically the case). This > patch uses the commit graph wherever possible; on my computer, when I > run the above command with a list of 1 object on a many-ref repository, > I get a speedup from 1.8s to 1.0s. > > Another way to accomplish this effect would be to modify parse_object() > to use the commit graph if possible; however, I did not want to change > parse_object()'s current behavior of always checking the object > signature of the returned object. > > Signed-off-by: Jonathan Tan <jonathantanmy@xxxxxxxxxx> > --- > This patch is still on master. Junio, let me know if you would rather > have me base it on sb/more-repo-in-api instead. Unless we all agree that we will abandon sb/more-repo-in-api, rerolling this on 'master' will force me to resolve similar but different conflicts every time. Unless we fast-track that other topic, that is, but I do not think that is what you meant to do. > Change in v3: Now uses a simpler API with the algorithm suggested by > Peff in [2], except that I also retain the existing optimization that > checks if graph_pos is already set. OK.
