branchmap: Save changectx creation during update
The newly introduced `branchmap` function allows us to skip the
creation of changectx objects. This speeds up the construction of
the branchmap.
On the mozilla repository (117293 changesets, 15490 mutable)
Before:
! impactable 19.9
! mutable 0.576
! unserved 3.16
After:
! impactable 7.03 (2.8x faster)
! mutable 0.352 (1.6x)
! unserved 1.15 (2.7x)
On the cpython repository (81418 changesets, 6418 mutable)
Before:
! impactable 15.9
! mutable 0.451
! unserved 0.861
After:
! impactable 6.55 (2.4x faster)
! mutable 0.170 (2.6x faster)
! unserved 0.289 (2.9x faster)
On the pypy repository (58852 changesets)
Before:
! impactable 13.6
After:
! impactable 6.17 (2.2x faster)
On my Mercurial repository (18295 changesets, 2210 mutable)
Before:
! impactable 23.9
! mutable 0.368
! unserved 0.057
After:
! impactable 1.31 (18x faster)
! mutable 0.042 (8.7x)
! unserved 0.025 (2.2x)
--- a/mercurial/branchmap.py Thu Jan 10 00:41:40 2013 +0100
+++ b/mercurial/branchmap.py Fri Jan 11 18:47:42 2013 +0100
@@ -149,11 +149,11 @@
heads missing, this function updates self to be correct.
"""
cl = repo.changelog
- ctxgen = (repo[r] for r in revgen)
# collect new branch entries
newbranches = {}
- for c in ctxgen:
- newbranches.setdefault(c.branch(), []).append(c.node())
+ getbranch = cl.branch
+ for r in revgen:
+ newbranches.setdefault(getbranch(r), []).append(cl.node(r))
# if older branchheads are reachable from new ones, they aren't
# really branchheads. Note checking parents is insufficient:
# 1 (branch a) -> 2 (branch b) -> 3 (branch a)