hbisect: confine loop to the relevant interval

In this context we know that ancestors[rev] == None for all rev <= goodrev,
so looping further back is unnecessary (and confusing).

mercurial/hbisect.py

@@ -1,155 +1,155
 # changelog bisection for mercurial
 #
 # Copyright 2007 Matt Mackall
 # Copyright 2005, 2006 Benoit Boissinot <[e-mail]>
 #
 # Inspired by git bisect, extension skeleton taken from mq.py.
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 import os
 from i18n import _
 from node import short, hex
 import util
 
 def bisect(changelog, state):
     """find the next node (if any) for testing during a bisect search.
     returns a (nodes, number, good) tuple.
 
     'nodes' is the final result of the bisect if 'number' is 0.
     Otherwise 'number' indicates the remaining possible candidates for
     the search and 'nodes' contains the next bisect target.
     'good' is True if bisect is searching for a first good changeset, False
     if searching for a first bad one.
     """
 
     clparents = changelog.parentrevs
     skip = set([changelog.rev(n) for n in state['skip']])
 
     def buildancestors(bad, good):
         # only the earliest bad revision matters
         badrev = min([changelog.rev(n) for n in bad])
         goodrevs = [changelog.rev(n) for n in good]
         goodrev = min(goodrevs)
         # build visit array
         ancestors = [None] * (len(changelog) + 1) # an extra for [-1]
 
         # set nodes descended from goodrev
         ancestors[goodrev] = []
         for rev in xrange(goodrev + 1, len(changelog)):
             for prev in clparents(rev):
                 if ancestors[prev] == []:
                     ancestors[rev] = []
 
         # clear good revs from array
         for node in goodrevs:
             ancestors[node] = None
-        for rev in xrange(len(changelog), -1, -1):
+        for rev in xrange(len(changelog), goodrev, -1):
             if ancestors[rev] is None:
                 for prev in clparents(rev):
                     ancestors[prev] = None
 
         if ancestors[badrev] is None:
             return badrev, None
         return badrev, ancestors
 
     good = False
     badrev, ancestors = buildancestors(state['bad'], state['good'])
     if not ancestors: # looking for bad to good transition?
         good = True
         badrev, ancestors = buildancestors(state['good'], state['bad'])
     bad = changelog.node(badrev)
     if not ancestors: # now we're confused
         if len(state['bad']) == 1 and len(state['good']) == 1:
             raise util.Abort(_("starting revisions are not directly related"))
         raise util.Abort(_("inconsistent state, %s:%s is good and bad")
                          % (badrev, short(bad)))
 
     # build children dict
     children = {}
     visit = [badrev]
     candidates = []
     while visit:
         rev = visit.pop(0)
         if ancestors[rev] == []:
             candidates.append(rev)
             for prev in clparents(rev):
                 if prev != -1:
                     if prev in children:
                         children[prev].append(rev)
                     else:
                         children[prev] = [rev]
                         visit.append(prev)
 
     candidates.sort()
     # have we narrowed it down to one entry?
     # or have all other possible candidates besides 'bad' have been skipped?
     tot = len(candidates)
     unskipped = [c for c in candidates if (c not in skip) and (c != badrev)]
     if tot == 1 or not unskipped:
         return ([changelog.node(rev) for rev in candidates], 0, good)
     perfect = tot // 2
 
     # find the best node to test
     best_rev = None
     best_len = -1
     poison = set()
     for rev in candidates:
         if rev in poison:
             # poison children
             poison.update(children.get(rev, []))
             continue
 
         a = ancestors[rev] or [rev]
         ancestors[rev] = None
 
         x = len(a) # number of ancestors
         y = tot - x # number of non-ancestors
         value = min(x, y) # how good is this test?
         if value > best_len and rev not in skip:
             best_len = value
             best_rev = rev
             if value == perfect: # found a perfect candidate? quit early
                 break
 
         if y < perfect and rev not in skip: # all downhill from here?
             # poison children
             poison.update(children.get(rev, []))
             continue
 
         for c in children.get(rev, []):
             if ancestors[c]:
                 ancestors[c] = list(set(ancestors[c] + a))
             else:
                 ancestors[c] = a + [c]
 
     assert best_rev is not None
     best_node = changelog.node(best_rev)
 
     return ([best_node], tot, good)
 
 
 def load_state(repo):
     state = {'good': [], 'bad': [], 'skip': []}
     if os.path.exists(repo.join("bisect.state")):
         for l in repo.opener("bisect.state"):
             kind, node = l[:-1].split()
             node = repo.lookup(node)
             if kind not in state:
                 raise util.Abort(_("unknown bisect kind %s") % kind)
             state[kind].append(node)
     return state
 
 
 def save_state(repo, state):
     f = repo.opener("bisect.state", "w", atomictemp=True)
     wlock = repo.wlock()
     try:
         for kind in state:
             for node in state[kind]:
                 f.write("%s %s\n" % (kind, hex(node)))
         f.rename()
     finally:
         wlock.release()