diff mercurial/revset.py @ 29938:2c6a05b938d8

revset: fix order of nested 'or' expression (BC)

This fixes the order of 'x & (y + z)' where 'y' and 'z' are not trivial.

The follow-order 'or' operation is slower than the ordered operation if
an input set is large:

       #0           #1           #2           #3
    0) 0.002968     0.002980     0.002982     0.073042
    1) 0.004513     0.004485     0.012029     0.075261

    #0: 0:4000 & (0:1099 + 1000:2099 + 2000:3099)
    #1: 4000:0 & (0:1099 + 1000:2099 + 2000:3099)
    #2: 10000:0 & (0:1099 + 1000:2099 + 2000:3099)
    #3: file("path:hg") & (0:1099 + 1000:2099 + 2000:3099)

I've tried another implementation, but which appeared to be slower than
this version.

    ss = [getset(repo, fullreposet(repo), x) for x in xs]
    return subset.filter(lambda r: any(r in s for s in ss), cache=False)

--- a/mercurial/revset.py	Sun Aug 07 17:58:50 2016 +0900
+++ b/mercurial/revset.py	Sun Jun 26 18:17:12 2016 +0900
@@ -407,7 +407,12 @@
     return a + b
 
 def orset(repo, subset, x, order):
-    return _orsetlist(repo, subset, getlist(x))
+    xs = getlist(x)
+    if order == followorder:
+        # slow path to take the subset order
+        return subset & _orsetlist(repo, fullreposet(repo), xs)
+    else:
+        return _orsetlist(repo, subset, xs)
 
 def notset(repo, subset, x, order):
     return subset - getset(repo, subset, x)