view contrib/synthrepo.py @ 17811:a8aba2921456

amend: add noise in extra to avoid creating obsolescence cycle (issue3664)

Obsolescence cycle are bad and should be avoided as much as possible. The
current amend implemented touch changeset meta data as few as possible. This
make is easy for amend to result in the same node than a precursors. We add some
deterministic noise in extra to avoid this. In practice, the hex of the amended
changeset is stored in 'amend_source' extra key.

# synthrepo.py - repo synthesis
#
# Copyright 2012 Facebook
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''synthesize structurally interesting change history

This extension is useful for creating a repository with properties
that are statistically similar to an existing repository. During
analysis, a simple probability table is constructed from the history
of an existing repository.  During synthesis, these properties are
reconstructed.

Properties that are analyzed and synthesized include the following:

- Lines added or removed when an existing file is modified
- Number and sizes of files added
- Number of files removed
- Line lengths
- Topological distance to parent changeset(s)
- Probability of a commit being a merge
- Probability of a newly added file being added to a new directory
- Interarrival time, and time zone, of commits

A few obvious properties that are not currently handled realistically:

- Merges are treated as regular commits with two parents, which is not
  realistic
- Modifications are not treated as operations on hunks of lines, but
  as insertions and deletions of randomly chosen single lines
- Committer ID (always random)
- Executability of files
- Symlinks and binary files are ignored
'''

import bisect, collections, json, os, random, time
from mercurial import cmdutil, context, patch, scmutil, url, util
from mercurial.i18n import _
from mercurial.node import nullrev, nullid

testedwith = 'internal'

cmdtable = {}
command = cmdutil.command(cmdtable)

newfile = set(('new fi', 'rename', 'copy f', 'copy t'))

def zerodict():
    return collections.defaultdict(lambda: 0)

def roundto(x, k):
    if x > k * 2:
        return int(round(x / float(k)) * k)
    return int(round(x))

def parsegitdiff(lines):
    filename, mar, lineadd, lineremove = None, None, zerodict(), 0
    binary = False
    for line in lines:
        start = line[:6]
        if start == 'diff -':
            if filename:
                yield filename, mar, lineadd, lineremove, binary
            mar, lineadd, lineremove, binary = 'm', zerodict(), 0, False
            filename = patch.gitre.match(line).group(1)
        elif start in newfile:
            mar = 'a'
        elif start == 'GIT bi':
            binary = True
        elif start == 'delete':
            mar = 'r'
        elif start:
            s = start[0]
            if s == '-' and not line.startswith('--- '):
                lineremove += 1
            elif s == '+' and not line.startswith('+++ '):
                lineadd[roundto(len(line) - 1, 5)] += 1
    if filename:
        yield filename, mar, lineadd, lineremove, binary

@command('analyze',
         [('o', 'output', [], _('write output to given file'), _('FILE')),
          ('r', 'rev', [], _('analyze specified revisions'), _('REV'))],
         _('hg analyze'))
def analyze(ui, repo, *revs, **opts):
    '''create a simple model of a repository to use for later synthesis

    This command examines every changeset in the given range (or all
    of history if none are specified) and creates a simple statistical
    model of the history of the repository.

    The model is written out to a JSON file, and can be used by
    :hg:`synthesize` to create or augment a repository with synthetic
    commits that have a structure that is statistically similar to the
    analyzed repository.
    '''

    revs = list(revs)
    revs.extend(opts['rev'])
    if not revs:
        revs = [':']

    output = opts['output']
    if not output:
        output = os.path.basename(repo.root) + '.json'

    if output == '-':
        fp = sys.stdout
    else:
        fp = open(output, 'w')

    revs = scmutil.revrange(repo, revs)
    revs.sort()

    lineschanged = zerodict()
    children = zerodict()
    p1distance = zerodict()
    p2distance = zerodict()
    linesinfilesadded = zerodict()
    fileschanged = zerodict()
    filesadded = zerodict()
    filesremoved = zerodict()
    linelengths = zerodict()
    interarrival = zerodict()
    parents = zerodict()
    dirsadded = zerodict()
    tzoffset = zerodict()

    progress = ui.progress
    _analyzing = _('analyzing')
    _changesets = _('changesets')
    _total = len(revs)

    for i, rev in enumerate(revs):
        progress(_analyzing, i, unit=_changesets, total=_total)
        ctx = repo[rev]
        pl = ctx.parents()
        pctx = pl[0]
        prev = pctx.rev()
        children[prev] += 1
        p1distance[rev - prev] += 1
        parents[len(pl)] += 1
        tzoffset[ctx.date()[1]] += 1
        if len(pl) > 1:
            p2distance[rev - pl[1].rev()] += 1
        if prev == rev - 1:
            lastctx = pctx
        else:
            lastctx = repo[rev - 1]
        if lastctx.rev() != nullrev:
            interarrival[roundto(ctx.date()[0] - lastctx.date()[0], 300)] += 1
        diff = sum((d.splitlines()
                    for d in ctx.diff(pctx, opts=dict(git=True))), [])
        fileadds, diradds, fileremoves, filechanges = 0, 0, 0, 0
        for filename, mar, lineadd, lineremove, binary in parsegitdiff(diff):
            if binary:
                continue
            added = sum(lineadd.itervalues(), 0)
            if mar == 'm':
                if added and lineremove:
                    lineschanged[roundto(added, 5), roundto(lineremove, 5)] += 1
                    filechanges += 1
            elif mar == 'a':
                fileadds += 1
                if '/' in filename:
                    filedir = filename.rsplit('/', 1)[0]
                    if filedir not in pctx.dirs():
                        diradds += 1
                linesinfilesadded[roundto(added, 5)] += 1
            elif mar == 'r':
                fileremoves += 1
            for length, count in lineadd.iteritems():
                linelengths[length] += count
        fileschanged[filechanges] += 1
        filesadded[fileadds] += 1
        dirsadded[diradds] += 1
        filesremoved[fileremoves] += 1

    invchildren = zerodict()

    for rev, count in children.iteritems():
        invchildren[count] += 1

    if output != '-':
        ui.status(_('writing output to %s\n') % output)

    def pronk(d):
        return sorted(d.iteritems(), key=lambda x: x[1], reverse=True)

    json.dump(dict(revs=len(revs),
                   lineschanged=pronk(lineschanged),
                   children=pronk(invchildren),
                   fileschanged=pronk(fileschanged),
                   filesadded=pronk(filesadded),
                   linesinfilesadded=pronk(linesinfilesadded),
                   dirsadded=pronk(dirsadded),
                   filesremoved=pronk(filesremoved),
                   linelengths=pronk(linelengths),
                   parents=pronk(parents),
                   p1distance=pronk(p1distance),
                   p2distance=pronk(p2distance),
                   interarrival=pronk(interarrival),
                   tzoffset=pronk(tzoffset),
                   ),
              fp)
    fp.close()

@command('synthesize',
         [('c', 'count', 0, _('create given number of commits'), _('COUNT')),
          ('', 'dict', '', _('path to a dictionary of words'), _('FILE'))],
         _('hg synthesize [OPTION].. DESCFILE'))
def synthesize(ui, repo, descpath, **opts):
    '''synthesize commits based on a model of an existing repository

    The model must have been generated by :hg:`analyze`. Commits will
    be generated randomly according to the probabilities described in
    the model.

    When synthesizing new content, commit descriptions, and user
    names, words will be chosen randomly from a dictionary that is
    presumed to contain one word per line. Use --dict to specify the
    path to an alternate dictionary to use.
    '''
    try:
        fp = url.open(ui, descpath)
    except Exception, err:
        raise util.Abort('%s: %s' % (descpath, err[0].strerror))
    desc = json.load(fp)
    fp.close()

    def cdf(l):
        vals, probs = zip(*sorted(l, key=lambda x: x[1], reverse=True))
        t = float(sum(probs, 0))
        s, cdfs = 0, []
        for v in probs:
            s += v
            cdfs.append(s / t)
        return vals, cdfs

    lineschanged = cdf(desc['lineschanged'])
    fileschanged = cdf(desc['fileschanged'])
    filesadded = cdf(desc['filesadded'])
    dirsadded = cdf(desc['dirsadded'])
    filesremoved = cdf(desc['filesremoved'])
    linelengths = cdf(desc['linelengths'])
    parents = cdf(desc['parents'])
    p1distance = cdf(desc['p1distance'])
    p2distance = cdf(desc['p2distance'])
    interarrival = cdf(desc['interarrival'])
    linesinfilesadded = cdf(desc['linesinfilesadded'])
    tzoffset = cdf(desc['tzoffset'])

    dictfile = opts.get('dict') or '/usr/share/dict/words'
    try:
        fp = open(dictfile, 'rU')
    except IOError, err:
        raise util.Abort('%s: %s' % (dictfile, err.strerror))
    words = fp.read().splitlines()
    fp.close()

    def pick(cdf):
        return cdf[0][bisect.bisect_left(cdf[1], random.random())]

    def makeline(minimum=0):
        total = max(minimum, pick(linelengths))
        c, l = 0, []
        while c < total:
            w = random.choice(words)
            c += len(w) + 1
            l.append(w)
        return ' '.join(l)

    wlock = repo.wlock()
    lock = repo.lock()

    nevertouch = set(('.hgsub', '.hgignore', '.hgtags'))

    progress = ui.progress
    _synthesizing = _('synthesizing')
    _changesets = _('changesets')

    count = int(opts['count'])
    heads = set(map(repo.changelog.rev, repo.heads()))
    for i in xrange(count):
        progress(_synthesizing, i, unit=_changesets, total=count)

        node = repo.changelog.node
        revs = len(repo)

        def pickhead(heads, distance):
            if heads:
                lheads = sorted(heads)
                rev = revs - min(pick(distance), revs)
                if rev < lheads[-1]:
                    rev = lheads[bisect.bisect_left(lheads, rev)]
                else:
                    rev = lheads[-1]
                return rev, node(rev)
            return nullrev, nullid

        r1 = revs - min(pick(p1distance), revs)
        p1 = node(r1)

        # the number of heads will grow without bound if we use a pure
        # model, so artificially constrain their proliferation
        if pick(parents) == 2 or len(heads) > random.randint(1, 20):
            r2, p2 = pickhead(heads.difference([r1]), p2distance)
        else:
            r2, p2 = nullrev, nullid

        pl = [p1, p2]
        pctx = repo[r1]
        mf = pctx.manifest()
        mfk = mf.keys()
        changes = {}
        if mfk:
            for __ in xrange(pick(fileschanged)):
                for __ in xrange(10):
                    fctx = pctx.filectx(random.choice(mfk))
                    path = fctx.path()
                    if not (path in nevertouch or fctx.isbinary() or
                            'l' in fctx.flags()):
                        break
                lines = fctx.data().splitlines()
                add, remove = pick(lineschanged)
                for __ in xrange(remove):
                    if not lines:
                        break
                    del lines[random.randrange(0, len(lines))]
                for __ in xrange(add):
                    lines.insert(random.randint(0, len(lines)), makeline())
                path = fctx.path()
                changes[path] = context.memfilectx(path,
                                                   '\n'.join(lines) + '\n')
            for __ in xrange(pick(filesremoved)):
                path = random.choice(mfk)
                for __ in xrange(10):
                    path = random.choice(mfk)
                    if path not in changes:
                        changes[path] = None
                        break
        if filesadded:
            dirs = list(pctx.dirs())
            dirs.append('')
        for __ in xrange(pick(filesadded)):
            path = [random.choice(dirs)]
            if pick(dirsadded):
                path.append(random.choice(words))
            path.append(random.choice(words))
            path = '/'.join(filter(None, path))
            data = '\n'.join(makeline()
                             for __ in xrange(pick(linesinfilesadded))) + '\n'
            changes[path] = context.memfilectx(path, data)
        def filectxfn(repo, memctx, path):
            data = changes[path]
            if data is None:
                raise IOError
            return data
        if not changes:
            continue
        if revs:
            date = repo['tip'].date()[0] + pick(interarrival)
        else:
            date = time.time() - (86400 * count)
        user = random.choice(words) + '@' + random.choice(words)
        mc = context.memctx(repo, pl, makeline(minimum=2),
                            sorted(changes.iterkeys()),
                            filectxfn, user, '%d %d' % (date, pick(tzoffset)))
        newnode = mc.commit()
        heads.add(repo.changelog.rev(newnode))
        heads.discard(r1)
        heads.discard(r2)

    lock.release()
    wlock.release()