# changelog bisection for mercurial## Copyright 2007 Matt Mackall# Copyright 2005, 2006 Benoit Boissinot <benoit.boissinot@ens-lyon.org>## 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, incorporated herein by reference. import osfrom i18n import _from node import short, heximport 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]        # build ancestors array        ancestors = [[]] * (len(changelog) + 1) # an extra for [-1]         # clear good revs from array        for node in goodrevs:            ancestors[node] = None        for rev in xrange(len(changelog), -1, -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 = 0    badrev, ancestors = buildancestors(state['bad'], state['good'])    if not ancestors: # looking for bad to good transition?        good = 1        badrev, ancestors = buildancestors(state['good'], state['bad'])    bad = changelog.node(badrev)    if not ancestors: # now we're confused        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()