# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1497743949 -32400
# Node ID d3d36bcdf0361f874d91516204fd8a778bd58c72
# Parent  08e2793d9f654fda6276c894318bb797cafd08e0
dagop: just compare with the last value to deduplicate input of revancestors()

Since we're using a max heap, the current rev should be a duplicate only
if it equals to the previous one. We don't have to maintain the whole seen
set.

  # reverse(ancestors(tip)) using hg repo
  0) 0.086420
  1) 0.081051

diff -r 08e2793d9f65 -r d3d36bcdf036 mercurial/dagop.py
--- a/mercurial/dagop.py	Sun Jun 18 17:22:57 2017 +0900
+++ b/mercurial/dagop.py	Sun Jun 18 08:59:09 2017 +0900
@@ -37,15 +37,15 @@
     if inputrev is not None:
         heapq.heappush(pendingheap, -inputrev)
 
-    seen = set()
+    lastrev = None
     while pendingheap:
         currev = -heapq.heappop(pendingheap)
         if currev == inputrev:
             inputrev = next(irevs, None)
             if inputrev is not None:
                 heapq.heappush(pendingheap, -inputrev)
-        if currev not in seen:
-            seen.add(currev)
+        if currev != lastrev:
+            lastrev = currev
             yield currev
             try:
                 for prev in cl.parentrevs(currev)[:cut]: