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diff mercurial/revset.py @ 26109:15412bba5a68

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revset: prefetch all attributes before loop in _revsbetween Python is slow at attributes lookup. No, really, I mean -slow-. prefetching these three methods give use a measurable performance boost. revset #0: 0::tip plain 0) 0.037655 1) 0.034290 91%
author Pierre-Yves David <pierre-yves.david@fb.com>
date Thu, 11 Jun 2015 11:42:46 -0700
parents 94441df6206c
children f140d6207cca
line wrap: on
line diff
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -91,23 +91,27 @@
     # (and if it is not, it should.)
     minroot = min(roots)
     roots = set(roots)
+    # prefetch all the things! (because python is slow)
+    reached = reachable.add
+    dovisit = visit.append
+    nextvisit = visit.pop
     # open-code the post-order traversal due to the tiny size of
     # sys.getrecursionlimit()
     while visit:
-        rev = visit.pop()
+        rev = nextvisit()
         if rev in roots:
-            reachable.add(rev)
+            reached(rev)
         parents = parentrevs(rev)
         seen[rev] = parents
         for parent in parents:
             if parent >= minroot and parent not in seen:
-                visit.append(parent)
+                dovisit(parent)
     if not reachable:
         return baseset()
     for rev in sorted(seen):
         for parent in seen[rev]:
             if parent in reachable:
-                reachable.add(rev)
+                reached(rev)
     return baseset(sorted(reachable))
 
 elements = {