diff mercurial/revsetlang.py @ 38625:52f19a840543

revset: add optimization for heads(commonancestors())

Previously, the only way to get these commits were (tested on
mozilla-central):

hg perfrevset 'heads(::a7cf55 and ::d8b15)'
! wall 4.988366 comb 4.960000 user 4.780000 sys 0.180000 (best of 3)

After this patch:

(python)
hg perfrevset 'heads(commonancestors(a7cf55 + d8b15))'
! wall 0.002155 comb 0.000000 user 0.000000 sys 0.000000 (best of 1107)

(C)
hg perfrevset 'heads(commonancestors(a7cf55 + d8b15))'
! wall 0.000568 comb 0.000000 user 0.000000 sys 0.000000 (best of 4646)

--- a/mercurial/revsetlang.py	Mon Jun 18 19:41:54 2018 -0700
+++ b/mercurial/revsetlang.py	Tue Jun 26 15:26:21 2018 -0700
@@ -459,6 +459,12 @@
         f = getsymbol(x[1])
         wa, ta = _optimize(x[2])
         w = getattr(symbols.get(f), '_weight', 1)
+        m = _match('commonancestors(_)', ta)
+
+        # Optimize heads(commonancestors(_)) because we have a fast version
+        if f == 'heads' and m:
+            return w + wa, _build('_commonancestorheads(_)', m[1])
+
         return w + wa, (op, x[1], ta)
     raise ValueError('invalid operator %r' % op)