How to speed up revset evaluation (short-circuit &)?

[jaustin-ant]

Many of my revsets, e.g. mine() are very slow in a large monorepo. I'm curious if there's a way of short-circuiting this by e.g. author_date(after:"7 days ago") & mine(). I tried a bunch of approaches and couldn't find any.

[scott2000]

Revsets like mine() and author_date() are evaluated as filters, so they will scan the entire history of the repo unless restricted using some other revset. Usually it's good to use x.., x..y or x:: along with these revsets, because that prevents them from having to scan the entire history.

For instance, you might find more success with something like author_date(before:"7 days ago").. & mine(), because that tells the optimizer that it can stop scanning backwards when it finds a commit from before 7 days ago (whereas for author_date(after:"7 days ago") & mine() it can't stop early, because it's technically possible that a commit can have an older author date than its parent, such as if it were rebased).

Another option would be to do something like mutable() & mine(), trunk().. & mine(), or v10.0.0.. & mine(). It's very common that restricting a query to mutable() will make evaluation faster, since that allows the revset engine to stop scanning backwards whenever it runs into an ancestor of immutable_heads().

[jaustin-ant]

Thanks for the quick reply!

[jaustin-ant]

As a minor follow-up, (author_date(before:"7 days ago")..) & mine() is fast but (author_date(before:"7 days ago")..) & mine()- is still slow. I guess in this case it can't short-circuit because its parent could actually be younger?

[scott2000]

That's actually happening because evaluating mine()- requires first evaluating mine() fully, and then finding the parents of those commits. You would have to put the range operator inside of the parents/- operator to make it fast I believe, like parents(author_date(before:"7 days ago").. & mine()).

Edit: fixed typo in revset

[jaustin-ant]

Amazing. Now I have this neat little utility I like

[revset-aliases]
'stack()' = 'reachable((fork_point(trunk() | @))..@, fork_point(trunk() | @)..)| git_head()'
'recentmine()' = 'author_date(before:"7 days ago").. & mine()'

[aliases]
stack = ["log", "-r", "stack() & (recentmine() | recentmine()-)"]

mutable() also speeds it up, I might use that although I don't (yet) know what determines mutability.

Thanks a lot!

[scott2000]

Nice! You could also maybe simplify recentmine() | recentmine()- by doing ancestors(recentmine(), 2) instead, which makes it easier if you later decide you want even more ancestors.