annotate hgext/convert/filemap.py @ 17103:5146de7bce96

convert: keep branch switching merges with ancestors (issue3340)

When running convert with a filemap, merge parents which are ancestors
of other parents are ignored. This is hardly a problem when parents
belong to the same branch, but the result could be confusing when named
branches are involved. With:

  -o-a1-a2-a3...     <- A
    \           \
     b1-b2-b3...-m-  <- B

If all b* revisions are discarded, it is useful to preserve 'm' even if
it is empty after filtering to record the branch switch.

This patch makes filemap preserve "ancestor parents" if there is no
"non-ancestor parent" on the same branch than the merge revision.

Remarks:
- I am not completely convinced by the reasons given above and those
  detailed by Matt in this thread:

http://selenic.com/pipermail/mercurial-devel/2012-May/040627.html

  The properties we try to preserve are not clearly defined. That said,
  I know this patch already helped someone on IRC and the tests output
  look reasonable.

- This is a new version of the original "convert: filemap must preserve
  fast-forward merges" patch. It has exactly the same output for 2
  parents merges, the additional complexity is here to handle more than
  two parents.

# Copyright 2007 Bryan O'Sullivan <[e-mail]>
# Copyright 2007 Alexis S. L. Carvalho <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import shlex
from mercurial.i18n import _
from mercurial import util
from common import SKIPREV, converter_source

def rpairs(name):
    e = len(name)
    while e != -1:
        yield name[:e], name[e + 1:]
        e = name.rfind('/', 0, e)
    yield '.', name

class filemapper(object):
    '''Map and filter filenames when importing.
    A name can be mapped to itself, a new name, or None (omit from new
    repository).'''

    def __init__(self, ui, path=None):
        self.ui = ui
        self.include = {}
        self.exclude = {}
        self.rename = {}
        if path:
            if self.parse(path):
                raise util.Abort(_('errors in filemap'))

    def parse(self, path):
        errs = 0
        def check(name, mapping, listname):
            if not name:
                self.ui.warn(_('%s:%d: path to %s is missing\n') %
                             (lex.infile, lex.lineno, listname))
                return 1
            if name in mapping:
                self.ui.warn(_('%s:%d: %r already in %s list\n') %
                             (lex.infile, lex.lineno, name, listname))
                return 1
            if (name.startswith('/') or
                name.endswith('/') or
                '//' in name):
                self.ui.warn(_('%s:%d: superfluous / in %s %r\n') %
                             (lex.infile, lex.lineno, listname, name))
                return 1
            return 0
        lex = shlex.shlex(open(path), path, True)
        lex.wordchars += '!@#$%^&*()-=+[]{}|;:,./<>?'
        cmd = lex.get_token()
        while cmd:
            if cmd == 'include':
                name = lex.get_token()
                errs += check(name, self.exclude, 'exclude')
                self.include[name] = name
            elif cmd == 'exclude':
                name = lex.get_token()
                errs += check(name, self.include, 'include')
                errs += check(name, self.rename, 'rename')
                self.exclude[name] = name
            elif cmd == 'rename':
                src = lex.get_token()
                dest = lex.get_token()
                errs += check(src, self.exclude, 'exclude')
                self.rename[src] = dest
            elif cmd == 'source':
                errs += self.parse(lex.get_token())
            else:
                self.ui.warn(_('%s:%d: unknown directive %r\n') %
                             (lex.infile, lex.lineno, cmd))
                errs += 1
            cmd = lex.get_token()
        return errs

    def lookup(self, name, mapping):
        for pre, suf in rpairs(name):
            try:
                return mapping[pre], pre, suf
            except KeyError:
                pass
        return '', name, ''

    def __call__(self, name):
        if self.include:
            inc = self.lookup(name, self.include)[0]
        else:
            inc = name
        if self.exclude:
            exc = self.lookup(name, self.exclude)[0]
        else:
            exc = ''
        if (not self.include and exc) or (len(inc) <= len(exc)):
            return None
        newpre, pre, suf = self.lookup(name, self.rename)
        if newpre:
            if newpre == '.':
                return suf
            if suf:
                if newpre.endswith('/'):
                    return newpre + suf
                return newpre + '/' + suf
            return newpre
        return name

    def active(self):
        return bool(self.include or self.exclude or self.rename)

# This class does two additional things compared to a regular source:
#
# - Filter and rename files.  This is mostly wrapped by the filemapper
#   class above. We hide the original filename in the revision that is
#   returned by getchanges to be able to find things later in getfile.
#
# - Return only revisions that matter for the files we're interested in.
#   This involves rewriting the parents of the original revision to
#   create a graph that is restricted to those revisions.
#
#   This set of revisions includes not only revisions that directly
#   touch files we're interested in, but also merges that merge two
#   or more interesting revisions.

class filemap_source(converter_source):
    def __init__(self, ui, baseconverter, filemap):
        super(filemap_source, self).__init__(ui)
        self.base = baseconverter
        self.filemapper = filemapper(ui, filemap)
        self.commits = {}
        # if a revision rev has parent p in the original revision graph, then
        # rev will have parent self.parentmap[p] in the restricted graph.
        self.parentmap = {}
        # self.wantedancestors[rev] is the set of all ancestors of rev that
        # are in the restricted graph.
        self.wantedancestors = {}
        self.convertedorder = None
        self._rebuilt = False
        self.origparents = {}
        self.children = {}
        self.seenchildren = {}

    def before(self):
        self.base.before()

    def after(self):
        self.base.after()

    def setrevmap(self, revmap):
        # rebuild our state to make things restartable
        #
        # To avoid calling getcommit for every revision that has already
        # been converted, we rebuild only the parentmap, delaying the
        # rebuild of wantedancestors until we need it (i.e. until a
        # merge).
        #
        # We assume the order argument lists the revisions in
        # topological order, so that we can infer which revisions were
        # wanted by previous runs.
        self._rebuilt = not revmap
        seen = {SKIPREV: SKIPREV}
        dummyset = set()
        converted = []
        for rev in revmap.order:
            mapped = revmap[rev]
            wanted = mapped not in seen
            if wanted:
                seen[mapped] = rev
                self.parentmap[rev] = rev
            else:
                self.parentmap[rev] = seen[mapped]
            self.wantedancestors[rev] = dummyset
            arg = seen[mapped]
            if arg == SKIPREV:
                arg = None
            converted.append((rev, wanted, arg))
        self.convertedorder = converted
        return self.base.setrevmap(revmap)

    def rebuild(self):
        if self._rebuilt:
            return True
        self._rebuilt = True
        self.parentmap.clear()
        self.wantedancestors.clear()
        self.seenchildren.clear()
        for rev, wanted, arg in self.convertedorder:
            if rev not in self.origparents:
                self.origparents[rev] = self.getcommit(rev).parents
            if arg is not None:
                self.children[arg] = self.children.get(arg, 0) + 1

        for rev, wanted, arg in self.convertedorder:
            parents = self.origparents[rev]
            if wanted:
                self.mark_wanted(rev, parents)
            else:
                self.mark_not_wanted(rev, arg)
            self._discard(arg, *parents)

        return True

    def getheads(self):
        return self.base.getheads()

    def getcommit(self, rev):
        # We want to save a reference to the commit objects to be able
        # to rewrite their parents later on.
        c = self.commits[rev] = self.base.getcommit(rev)
        for p in c.parents:
            self.children[p] = self.children.get(p, 0) + 1
        return c

    def _cachedcommit(self, rev):
        if rev in self.commits:
            return self.commits[rev]
        return self.base.getcommit(rev)

    def _discard(self, *revs):
        for r in revs:
            if r is None:
                continue
            self.seenchildren[r] = self.seenchildren.get(r, 0) + 1
            if self.seenchildren[r] == self.children[r]:
                del self.wantedancestors[r]
                del self.parentmap[r]
                del self.seenchildren[r]
                if self._rebuilt:
                    del self.children[r]

    def wanted(self, rev, i):
        # Return True if we're directly interested in rev.
        #
        # i is an index selecting one of the parents of rev (if rev
        # has no parents, i is None).  getchangedfiles will give us
        # the list of files that are different in rev and in the parent
        # indicated by i.  If we're interested in any of these files,
        # we're interested in rev.
        try:
            files = self.base.getchangedfiles(rev, i)
        except NotImplementedError:
            raise util.Abort(_("source repository doesn't support --filemap"))
        for f in files:
            if self.filemapper(f):
                return True
        return False

    def mark_not_wanted(self, rev, p):
        # Mark rev as not interesting and update data structures.

        if p is None:
            # A root revision. Use SKIPREV to indicate that it doesn't
            # map to any revision in the restricted graph.  Put SKIPREV
            # in the set of wanted ancestors to simplify code elsewhere
            self.parentmap[rev] = SKIPREV
            self.wantedancestors[rev] = set((SKIPREV,))
            return

        # Reuse the data from our parent.
        self.parentmap[rev] = self.parentmap[p]
        self.wantedancestors[rev] = self.wantedancestors[p]

    def mark_wanted(self, rev, parents):
        # Mark rev ss wanted and update data structures.

        # rev will be in the restricted graph, so children of rev in
        # the original graph should still have rev as a parent in the
        # restricted graph.
        self.parentmap[rev] = rev

        # The set of wanted ancestors of rev is the union of the sets
        # of wanted ancestors of its parents. Plus rev itself.
        wrev = set()
        for p in parents:
            wrev.update(self.wantedancestors[p])
        wrev.add(rev)
        self.wantedancestors[rev] = wrev

    def getchanges(self, rev):
        parents = self.commits[rev].parents
        if len(parents) > 1:
            self.rebuild()

        # To decide whether we're interested in rev we:
        #
        # - calculate what parents rev will have if it turns out we're
        #   interested in it.  If it's going to have more than 1 parent,
        #   we're interested in it.
        #
        # - otherwise, we'll compare it with the single parent we found.
        #   If any of the files we're interested in is different in the
        #   the two revisions, we're interested in rev.

        # A parent p is interesting if its mapped version (self.parentmap[p]):
        # - is not SKIPREV
        # - is still not in the list of parents (we don't want duplicates)
        # - is not an ancestor of the mapped versions of the other parents or
        #   there is no parent in the same branch than the current revision.
        mparents = []
        knownparents = set()
        branch = self.commits[rev].branch
        hasbranchparent = False
        for i, p1 in enumerate(parents):
            mp1 = self.parentmap[p1]
            if mp1 == SKIPREV or mp1 in knownparents:
                continue
            isancestor = util.any(p2 for p2 in parents
                                  if p1 != p2 and mp1 != self.parentmap[p2]
                                  and mp1 in self.wantedancestors[p2])
            if not isancestor and not hasbranchparent and len(parents) > 1:
                # This could be expensive, avoid unnecessary calls.
                if self._cachedcommit(p1).branch == branch:
                    hasbranchparent = True
            mparents.append((p1, mp1, i, isancestor))
            knownparents.add(mp1)
        # Discard parents ancestors of other parents if there is a
        # non-ancestor one on the same branch than current revision.
        if hasbranchparent:
            mparents = [p for p in mparents if not p[3]]
        wp = None
        if mparents:
            wp = max(p[2] for p in mparents)
            mparents = [p[1] for p in mparents]
        elif parents:
            wp = 0

        self.origparents[rev] = parents

        closed = False
        if 'close' in self.commits[rev].extra:
            # A branch closing revision is only useful if one of its
            # parents belong to the branch being closed
            pbranches = [self._cachedcommit(p).branch for p in mparents]
            if branch in pbranches:
                closed = True

        if len(mparents) < 2 and not closed and not self.wanted(rev, wp):
            # We don't want this revision.
            # Update our state and tell the convert process to map this
            # revision to the same revision its parent as mapped to.
            p = None
            if parents:
                p = parents[wp]
            self.mark_not_wanted(rev, p)
            self.convertedorder.append((rev, False, p))
            self._discard(*parents)
            return self.parentmap[rev]

        # We want this revision.
        # Rewrite the parents of the commit object
        self.commits[rev].parents = mparents
        self.mark_wanted(rev, parents)
        self.convertedorder.append((rev, True, None))
        self._discard(*parents)

        # Get the real changes and do the filtering/mapping. To be
        # able to get the files later on in getfile, we hide the
        # original filename in the rev part of the return value.
        changes, copies = self.base.getchanges(rev)
        newnames = {}
        files = []
        for f, r in changes:
            newf = self.filemapper(f)
            if newf:
                files.append((newf, (f, r)))
                newnames[f] = newf

        ncopies = {}
        for c in copies:
            newc = self.filemapper(c)
            if newc:
                newsource = self.filemapper(copies[c])
                if newsource:
                    ncopies[newc] = newsource

        return files, ncopies

    def getfile(self, name, rev):
        realname, realrev = rev
        return self.base.getfile(realname, realrev)

    def gettags(self):
        return self.base.gettags()

    def hasnativeorder(self):
        return self.base.hasnativeorder()

    def lookuprev(self, rev):
        return self.base.lookuprev(rev)

    def getbookmarks(self):
        return self.base.getbookmarks()