ancestor: use heapreplace() in place of heappop/heappush() This should be slightly faster. Overall perfancestors result:: cpython nginx mercurial ------------- ---------------- ---------------- ---------------- b6db2e80a9ce^ 0.103461 0.006303 0.035716 8eb2145ff0fb 0.192307 (x1.86) 0.012115 (x1.92) 0.052135 (x1.46) this patch 0.139986 (x1.35) 0.006389 (x1.01) 0.037176 (x1.04)

ancestor: rename local aliases of heapq functions in _lazyancestorsiter() The original names no longer look pretty. Just call them as heap*() instead.

ancestor: optimize _lazyancestorsiter() for contiguous chains If there's no revision between p1 and current, p1 must be the next revision to visit. In this case, we can get around the overhead of heappop/push operations. Note that this is faster than using heapreplace(). 'current - p1 == 1' could be generalized as 'all(r not in seen for r in xrange(p1, current)', but Python is too slow to do such thing.

ancestor: unroll loop of parents in _lazyancestorsiter() This change itself isn't major performance win, but it helps optimizing the visit loop for contiguous chains. See the next patch.