revset: make parents() O(number of parents)
Strip executes a revset like this:
max(parents(_intlist('1234\x001235')) - _intlist('1234\x001235'))
Previously the parents() revset would do 'subset & parents' which iterates over
each item in the subset and checks if it's in parents. subset is usually the
entire repo (a spanset) so this takes a while.
Reversing the parameters to be 'parents & subset' means the operation becomes
O(number of parents) instead of O(size of repo). It also means the result gets
evaluated immediately (since parents isn't a lazy set), but I think this is a
win in most scenarios.
This shaves 0.3 seconds off strip (amend/histedit/rebase/etc) for large repositories.
revset #0: parents(20000)
0) obsolete feature not enabled but 54243 markers found!
! wall 0.006256 comb 0.010000 user 0.010000 sys 0.000000 (best of 289)
1) obsolete feature not enabled but 54243 markers found!
! wall 0.000391 comb 0.000000 user 0.000000 sys 0.000000 (best of 4323)
--- a/contrib/revsetbenchmarks.txt Fri Sep 12 16:21:13 2014 -0700
+++ b/contrib/revsetbenchmarks.txt Fri Sep 12 15:00:51 2014 -0700
@@ -23,4 +23,5 @@
max(::(tip~20) - obsolete())
roots((0:tip)::)
(not public() - obsolete())
+parents(20000)
(20000::) - (20000)
--- a/mercurial/revset.py Fri Sep 12 16:21:13 2014 -0700
+++ b/mercurial/revset.py Fri Sep 12 15:00:51 2014 -0700
@@ -1236,7 +1236,7 @@
cl = repo.changelog
for r in getset(repo, spanset(repo), x):
ps.update(cl.parentrevs(r))
- return subset & ps
+ return baseset(ps) & subset
def parentspec(repo, subset, x, n):
"""``set^0``
--- a/tests/test-revset.t Fri Sep 12 16:21:13 2014 -0700
+++ b/tests/test-revset.t Fri Sep 12 15:00:51 2014 -0700
@@ -567,10 +567,10 @@
test intersecting something with an addset
$ log 'parents(outgoing() or removes(a))'
+ 8
1
4
5
- 8
check that conversion to only works
$ try --optimize '::3 - ::1'