match: add visitchildrenset complement to visitdir
`visitdir(d)` lets a caller query whether the directory is part of the matcher.
It can receive a response of 'all' (yes, and all children, you can stop calling
visitdir now), False (no, and no children either), or True (yes, either
something in this directory or a child is part of the matcher).
`visitchildrenset(d)` augments that by instead of returning True, it returns a
list of items to actually investigate. With this, code can be modified from:
for f in self.all_items:
if match.visitdir(self.dir + '/' + f):
<do stuff>
to be:
for f in self.all_items.intersect(match.visitchildrenset(self.dir)):
<do stuff>
use of this function can provide significant performance improvements,
especially when using narrow (so that the matcher is much smaller than the stuff
we see on disk) and/or treemanifests (so that we can avoid loading manifests for
trees that aren't part of the matcher).
Differential Revision: https://phab.mercurial-scm.org/D4130
https://bz.mercurial-scm.org/1877
$ hg init a
$ cd a
$ echo a > a
$ hg add a
$ hg ci -m 'a'
$ echo b > a
$ hg ci -m'b'
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg book main
$ hg book
* main 0:cb9a9f314b8b
$ echo c > c
$ hg add c
$ hg ci -m'c'
created new head
$ hg book
* main 2:d36c0562f908
$ hg heads
changeset: 2:d36c0562f908
bookmark: main
tag: tip
parent: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: c
changeset: 1:1e6c11564562
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
$ hg up 1e6c11564562
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(leaving bookmark main)
$ hg merge main
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg book
main 2:d36c0562f908
$ hg ci -m'merge'
$ hg book
main 2:d36c0562f908
$ cd ..