~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2005, 2006 Canonical Ltd

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

from copy import deepcopy
from cStringIO import StringIO
from unittest import TestSuite
import xml.sax.saxutils

import bzrlib.bzrdir as bzrdir
from bzrlib.decorators import needs_read_lock, needs_write_lock
import bzrlib.errors as errors
from bzrlib.errors import InvalidRevisionId
import bzrlib.gpg as gpg
from bzrlib.graph import Graph
from bzrlib.inter import InterObject
from bzrlib.knit import KnitVersionedFile
from bzrlib.lockable_files import LockableFiles, TransportLock
from bzrlib.lockdir import LockDir
from bzrlib.osutils import safe_unicode
from bzrlib.revision import NULL_REVISION
from bzrlib.store.versioned import VersionedFileStore, WeaveStore
from bzrlib.store.text import TextStore
from bzrlib.symbol_versioning import *
from bzrlib.trace import mutter
from bzrlib.tree import RevisionTree
from bzrlib.tsort import topo_sort
from bzrlib.testament import Testament
from bzrlib.tree import EmptyTree
import bzrlib.ui
from bzrlib.weave import WeaveFile
import bzrlib.xml5


class Repository(object):
    """Repository holding history for one or more branches.

    The repository holds and retrieves historical information including
    revisions and file history.  It's normally accessed only by the Branch,
    which views a particular line of development through that history.

    The Repository builds on top of Stores and a Transport, which respectively 
    describe the disk data format and the way of accessing the (possibly 
    remote) disk.
    """

    @needs_write_lock
    def add_inventory(self, revid, inv, parents):
        """Add the inventory inv to the repository as revid.
        
        :param parents: The revision ids of the parents that revid
                        is known to have and are in the repository already.

        returns the sha1 of the serialized inventory.
        """
        inv_text = bzrlib.xml5.serializer_v5.write_inventory_to_string(inv)
        inv_sha1 = bzrlib.osutils.sha_string(inv_text)
        inv_vf = self.control_weaves.get_weave('inventory',
                                               self.get_transaction())
        inv_vf.add_lines(revid, parents, bzrlib.osutils.split_lines(inv_text))
        return inv_sha1

    @needs_write_lock
    def add_revision(self, rev_id, rev, inv=None, config=None):
        """Add rev to the revision store as rev_id.

        :param rev_id: the revision id to use.
        :param rev: The revision object.
        :param inv: The inventory for the revision. if None, it will be looked
                    up in the inventory storer
        :param config: If None no digital signature will be created.
                       If supplied its signature_needed method will be used
                       to determine if a signature should be made.
        """
        if config is not None and config.signature_needed():
            if inv is None:
                inv = self.get_inventory(rev_id)
            plaintext = Testament(rev, inv).as_short_text()
            self.store_revision_signature(
                gpg.GPGStrategy(config), plaintext, rev_id)
        if not rev_id in self.get_inventory_weave():
            if inv is None:
                raise errors.WeaveRevisionNotPresent(rev_id,
                                                     self.get_inventory_weave())
            else:
                # yes, this is not suitable for adding with ghosts.
                self.add_inventory(rev_id, inv, rev.parent_ids)
        self._revision_store.add_revision(rev, self.get_transaction())   

    @needs_read_lock
    def _all_possible_ids(self):
        """Return all the possible revisions that we could find."""
        return self.get_inventory_weave().versions()

    @needs_read_lock
    def all_revision_ids(self):
        """Returns a list of all the revision ids in the repository. 

        These are in as much topological order as the underlying store can 
        present: for weaves ghosts may lead to a lack of correctness until
        the reweave updates the parents list.
        """
        if self._revision_store.text_store.listable():
            return self._revision_store.all_revision_ids(self.get_transaction())
        result = self._all_possible_ids()
        return self._eliminate_revisions_not_present(result)

    @needs_read_lock
    def _eliminate_revisions_not_present(self, revision_ids):
        """Check every revision id in revision_ids to see if we have it.

        Returns a set of the present revisions.
        """
        result = []
        for id in revision_ids:
            if self.has_revision(id):
               result.append(id)
        return result

    @staticmethod
    def create(a_bzrdir):
        """Construct the current default format repository in a_bzrdir."""
        return RepositoryFormat.get_default_format().initialize(a_bzrdir)

    def __init__(self, _format, a_bzrdir, control_files, _revision_store, control_store, text_store):
        """instantiate a Repository.

        :param _format: The format of the repository on disk.
        :param a_bzrdir: The BzrDir of the repository.

        In the future we will have a single api for all stores for
        getting file texts, inventories and revisions, then
        this construct will accept instances of those things.
        """
        object.__init__(self)
        self._format = _format
        # the following are part of the public API for Repository:
        self.bzrdir = a_bzrdir
        self.control_files = control_files
        self._revision_store = _revision_store
        self.text_store = text_store
        # backwards compatability
        self.weave_store = text_store
        # not right yet - should be more semantically clear ? 
        # 
        self.control_store = control_store
        self.control_weaves = control_store

    def lock_write(self):
        self.control_files.lock_write()

    def lock_read(self):
        self.control_files.lock_read()

    def is_locked(self):
        return self.control_files.is_locked()

    @needs_read_lock
    def missing_revision_ids(self, other, revision_id=None):
        """Return the revision ids that other has that this does not.
        
        These are returned in topological order.

        revision_id: only return revision ids included by revision_id.
        """
        return InterRepository.get(other, self).missing_revision_ids(revision_id)

    @staticmethod
    def open(base):
        """Open the repository rooted at base.

        For instance, if the repository is at URL/.bzr/repository,
        Repository.open(URL) -> a Repository instance.
        """
        control = bzrlib.bzrdir.BzrDir.open(base)
        return control.open_repository()

    def copy_content_into(self, destination, revision_id=None, basis=None):
        """Make a complete copy of the content in self into destination.
        
        This is a destructive operation! Do not use it on existing 
        repositories.
        """
        return InterRepository.get(self, destination).copy_content(revision_id, basis)

    def fetch(self, source, revision_id=None, pb=None):
        """Fetch the content required to construct revision_id from source.

        If revision_id is None all content is copied.
        """
        return InterRepository.get(source, self).fetch(revision_id=revision_id,
                                                       pb=pb)

    def unlock(self):
        self.control_files.unlock()

    @needs_read_lock
    def clone(self, a_bzrdir, revision_id=None, basis=None):
        """Clone this repository into a_bzrdir using the current format.

        Currently no check is made that the format of this repository and
        the bzrdir format are compatible. FIXME RBC 20060201.
        """
        if not isinstance(a_bzrdir._format, self.bzrdir._format.__class__):
            # use target default format.
            result = a_bzrdir.create_repository()
        # FIXME RBC 20060209 split out the repository type to avoid this check ?
        elif isinstance(a_bzrdir._format,
                      (bzrlib.bzrdir.BzrDirFormat4,
                       bzrlib.bzrdir.BzrDirFormat5,
                       bzrlib.bzrdir.BzrDirFormat6)):
            result = a_bzrdir.open_repository()
        else:
            result = self._format.initialize(a_bzrdir, shared=self.is_shared())
        self.copy_content_into(result, revision_id, basis)
        return result

    @needs_read_lock
    def has_revision(self, revision_id):
        """True if this repository has a copy of the revision."""
        return self._revision_store.has_revision_id(revision_id,
                                                    self.get_transaction())

    @needs_read_lock
    def get_revision_reconcile(self, revision_id):
        """'reconcile' helper routine that allows access to a revision always.
        
        This variant of get_revision does not cross check the weave graph
        against the revision one as get_revision does: but it should only
        be used by reconcile, or reconcile-alike commands that are correcting
        or testing the revision graph.
        """
        if not revision_id or not isinstance(revision_id, basestring):
            raise InvalidRevisionId(revision_id=revision_id, branch=self)
        return self._revision_store.get_revision(revision_id,
                                                 self.get_transaction())

    @needs_read_lock
    def get_revision_xml(self, revision_id):
        rev = self.get_revision(revision_id) 
        rev_tmp = StringIO()
        # the current serializer..
        self._revision_store._serializer.write_revision(rev, rev_tmp)
        rev_tmp.seek(0)
        return rev_tmp.getvalue()

    @needs_read_lock
    def get_revision(self, revision_id):
        """Return the Revision object for a named revision"""
        r = self.get_revision_reconcile(revision_id)
        # weave corruption can lead to absent revision markers that should be
        # present.
        # the following test is reasonably cheap (it needs a single weave read)
        # and the weave is cached in read transactions. In write transactions
        # it is not cached but typically we only read a small number of
        # revisions. For knits when they are introduced we will probably want
        # to ensure that caching write transactions are in use.
        inv = self.get_inventory_weave()
        self._check_revision_parents(r, inv)
        return r

    def _check_revision_parents(self, revision, inventory):
        """Private to Repository and Fetch.
        
        This checks the parentage of revision in an inventory weave for 
        consistency and is only applicable to inventory-weave-for-ancestry
        using repository formats & fetchers.
        """
        weave_parents = inventory.get_parents(revision.revision_id)
        weave_names = inventory.versions()
        for parent_id in revision.parent_ids:
            if parent_id in weave_names:
                # this parent must not be a ghost.
                if not parent_id in weave_parents:
                    # but it is a ghost
                    raise errors.CorruptRepository(self)

    @needs_write_lock
    def store_revision_signature(self, gpg_strategy, plaintext, revision_id):
        signature = gpg_strategy.sign(plaintext)
        self._revision_store.add_revision_signature_text(revision_id,
                                                         signature,
                                                         self.get_transaction())

    def fileid_involved_between_revs(self, from_revid, to_revid):
        """Find file_id(s) which are involved in the changes between revisions.

        This determines the set of revisions which are involved, and then
        finds all file ids affected by those revisions.
        """
        # TODO: jam 20060119 This code assumes that w.inclusions will
        #       always be correct. But because of the presence of ghosts
        #       it is possible to be wrong.
        #       One specific example from Robert Collins:
        #       Two branches, with revisions ABC, and AD
        #       C is a ghost merge of D.
        #       Inclusions doesn't recognize D as an ancestor.
        #       If D is ever merged in the future, the weave
        #       won't be fixed, because AD never saw revision C
        #       to cause a conflict which would force a reweave.
        w = self.get_inventory_weave()
        from_set = set(w.get_ancestry(from_revid))
        to_set = set(w.get_ancestry(to_revid))
        changed = to_set.difference(from_set)
        return self._fileid_involved_by_set(changed)

    def fileid_involved(self, last_revid=None):
        """Find all file_ids modified in the ancestry of last_revid.

        :param last_revid: If None, last_revision() will be used.
        """
        w = self.get_inventory_weave()
        if not last_revid:
            changed = set(w.versions())
        else:
            changed = set(w.get_ancestry(last_revid))
        return self._fileid_involved_by_set(changed)

    def fileid_involved_by_set(self, changes):
        """Find all file_ids modified by the set of revisions passed in.

        :param changes: A set() of revision ids
        """
        # TODO: jam 20060119 This line does *nothing*, remove it.
        #       or better yet, change _fileid_involved_by_set so
        #       that it takes the inventory weave, rather than
        #       pulling it out by itself.
        return self._fileid_involved_by_set(changes)

    def _fileid_involved_by_set(self, changes):
        """Find the set of file-ids affected by the set of revisions.

        :param changes: A set() of revision ids.
        :return: A set() of file ids.
        
        This peaks at the Weave, interpreting each line, looking to
        see if it mentions one of the revisions. And if so, includes
        the file id mentioned.
        This expects both the Weave format, and the serialization
        to have a single line per file/directory, and to have
        fileid="" and revision="" on that line.
        """
        assert isinstance(self._format, (RepositoryFormat5,
                                         RepositoryFormat6,
                                         RepositoryFormat7,
                                         RepositoryFormatKnit1)), \
            "fileid_involved only supported for branches which store inventory as unnested xml"

        w = self.get_inventory_weave()
        file_ids = set()

        for lineno, insert, deletes, line in w.walk(changes):
            start = line.find('file_id="')+9
            if start < 9: continue
            end = line.find('"', start)
            assert end>= 0
            file_id = xml.sax.saxutils.unescape(line[start:end])

            # check if file_id is already present
            if file_id in file_ids: continue

            start = line.find('revision="')+10
            if start < 10: continue
            end = line.find('"', start)
            assert end>= 0
            revision_id = xml.sax.saxutils.unescape(line[start:end])

            if revision_id in changes:
                file_ids.add(file_id)
        return file_ids

    @needs_read_lock
    def get_inventory_weave(self):
        return self.control_weaves.get_weave('inventory',
            self.get_transaction())

    @needs_read_lock
    def get_inventory(self, revision_id):
        """Get Inventory object by hash."""
        xml = self.get_inventory_xml(revision_id)
        return bzrlib.xml5.serializer_v5.read_inventory_from_string(xml)

    @needs_read_lock
    def get_inventory_xml(self, revision_id):
        """Get inventory XML as a file object."""
        try:
            assert isinstance(revision_id, basestring), type(revision_id)
            iw = self.get_inventory_weave()
            return iw.get_text(revision_id)
        except IndexError:
            raise bzrlib.errors.HistoryMissing(self, 'inventory', revision_id)

    @needs_read_lock
    def get_inventory_sha1(self, revision_id):
        """Return the sha1 hash of the inventory entry
        """
        return self.get_revision(revision_id).inventory_sha1

    @needs_read_lock
    def get_revision_graph(self, revision_id=None):
        """Return a dictionary containing the revision graph.
        
        :return: a dictionary of revision_id->revision_parents_list.
        """
        weave = self.get_inventory_weave()
        all_revisions = self._eliminate_revisions_not_present(weave.versions())
        entire_graph = dict([(node, weave.get_parents(node)) for 
                             node in all_revisions])
        if revision_id is None:
            return entire_graph
        elif revision_id not in entire_graph:
            raise errors.NoSuchRevision(self, revision_id)
        else:
            # add what can be reached from revision_id
            result = {}
            pending = set([revision_id])
            while len(pending) > 0:
                node = pending.pop()
                result[node] = entire_graph[node]
                for revision_id in result[node]:
                    if revision_id not in result:
                        pending.add(revision_id)
            return result

    @needs_read_lock
    def get_revision_graph_with_ghosts(self, revision_ids=None):
        """Return a graph of the revisions with ghosts marked as applicable.

        :param revision_ids: an iterable of revisions to graph or None for all.
        :return: a Graph object with the graph reachable from revision_ids.
        """
        result = Graph()
        if not revision_ids:
            pending = set(self.all_revision_ids())
            required = set([])
        else:
            pending = set(revision_ids)
            required = set(revision_ids)
        done = set([])
        while len(pending):
            revision_id = pending.pop()
            try:
                rev = self.get_revision(revision_id)
            except errors.NoSuchRevision:
                if revision_id in required:
                    raise
                # a ghost
                result.add_ghost(revision_id)
                continue
            for parent_id in rev.parent_ids:
                # is this queued or done ?
                if (parent_id not in pending and
                    parent_id not in done):
                    # no, queue it.
                    pending.add(parent_id)
            result.add_node(revision_id, rev.parent_ids)
            done.add(result)
        return result

    @needs_read_lock
    def get_revision_inventory(self, revision_id):
        """Return inventory of a past revision."""
        # TODO: Unify this with get_inventory()
        # bzr 0.0.6 and later imposes the constraint that the inventory_id
        # must be the same as its revision, so this is trivial.
        if revision_id is None:
            # This does not make sense: if there is no revision,
            # then it is the current tree inventory surely ?!
            # and thus get_root_id() is something that looks at the last
            # commit on the branch, and the get_root_id is an inventory check.
            raise NotImplementedError
            # return Inventory(self.get_root_id())
        else:
            return self.get_inventory(revision_id)

    @needs_read_lock
    def is_shared(self):
        """Return True if this repository is flagged as a shared repository."""
        # FIXME format 4-6 cannot be shared, this is technically faulty.
        return self.control_files._transport.has('shared-storage')

    @needs_read_lock
    def revision_tree(self, revision_id):
        """Return Tree for a revision on this branch.

        `revision_id` may be None for the null revision, in which case
        an `EmptyTree` is returned."""
        # TODO: refactor this to use an existing revision object
        # so we don't need to read it in twice.
        if revision_id is None or revision_id == NULL_REVISION:
            return EmptyTree()
        else:
            inv = self.get_revision_inventory(revision_id)
            return RevisionTree(self, inv, revision_id)

    @needs_read_lock
    def get_ancestry(self, revision_id):
        """Return a list of revision-ids integrated by a revision.
        
        This is topologically sorted.
        """
        if revision_id is None:
            return [None]
        if not self.has_revision(revision_id):
            raise errors.NoSuchRevision(self, revision_id)
        w = self.get_inventory_weave()
        return [None] + w.get_ancestry(revision_id)

    @needs_read_lock
    def print_file(self, file, revision_id):
        """Print `file` to stdout.
        
        FIXME RBC 20060125 as John Meinel points out this is a bad api
        - it writes to stdout, it assumes that that is valid etc. Fix
        by creating a new more flexible convenience function.
        """
        tree = self.revision_tree(revision_id)
        # use inventory as it was in that revision
        file_id = tree.inventory.path2id(file)
        if not file_id:
            raise BzrError("%r is not present in revision %s" % (file, revno))
            try:
                revno = self.revision_id_to_revno(revision_id)
            except errors.NoSuchRevision:
                # TODO: This should not be BzrError,
                # but NoSuchFile doesn't fit either
                raise BzrError('%r is not present in revision %s' 
                                % (file, revision_id))
            else:
                raise BzrError('%r is not present in revision %s'
                                % (file, revno))
        tree.print_file(file_id)

    def get_transaction(self):
        return self.control_files.get_transaction()

    def revision_parents(self, revid):
        return self.get_inventory_weave().parent_names(revid)

    @needs_write_lock
    def set_make_working_trees(self, new_value):
        """Set the policy flag for making working trees when creating branches.

        This only applies to branches that use this repository.

        The default is 'True'.
        :param new_value: True to restore the default, False to disable making
                          working trees.
        """
        # FIXME: split out into a new class/strategy ?
        if isinstance(self._format, (RepositoryFormat4,
                                     RepositoryFormat5,
                                     RepositoryFormat6)):
            raise NotImplementedError(self.set_make_working_trees)
        if new_value:
            try:
                self.control_files._transport.delete('no-working-trees')
            except errors.NoSuchFile:
                pass
        else:
            self.control_files.put_utf8('no-working-trees', '')
    
    def make_working_trees(self):
        """Returns the policy for making working trees on new branches."""
        # FIXME: split out into a new class/strategy ?
        if isinstance(self._format, (RepositoryFormat4,
                                     RepositoryFormat5,
                                     RepositoryFormat6)):
            return True
        return not self.control_files._transport.has('no-working-trees')

    @needs_write_lock
    def sign_revision(self, revision_id, gpg_strategy):
        plaintext = Testament.from_revision(self, revision_id).as_short_text()
        self.store_revision_signature(gpg_strategy, plaintext, revision_id)

    @needs_read_lock
    def has_signature_for_revision_id(self, revision_id):
        """Query for a revision signature for revision_id in the repository."""
        return self._revision_store.has_signature(revision_id,
                                                  self.get_transaction())

    @needs_read_lock
    def get_signature_text(self, revision_id):
        """Return the text for a signature."""
        return self._revision_store.get_signature_text(revision_id,
                                                       self.get_transaction())


class AllInOneRepository(Repository):
    """Legacy support - the repository behaviour for all-in-one branches."""

    def __init__(self, _format, a_bzrdir, _revision_store, control_store, text_store):
        # we reuse one control files instance.
        dir_mode = a_bzrdir._control_files._dir_mode
        file_mode = a_bzrdir._control_files._file_mode

        def get_weave(name, prefixed=False):
            if name:
                name = safe_unicode(name)
            else:
                name = ''
            relpath = a_bzrdir._control_files._escape(name)
            weave_transport = a_bzrdir._control_files._transport.clone(relpath)
            ws = WeaveStore(weave_transport, prefixed=prefixed,
                            dir_mode=dir_mode,
                            file_mode=file_mode)
            if a_bzrdir._control_files._transport.should_cache():
                ws.enable_cache = True
            return ws

        def get_store(name, compressed=True, prefixed=False):
            # FIXME: This approach of assuming stores are all entirely compressed
            # or entirely uncompressed is tidy, but breaks upgrade from 
            # some existing branches where there's a mixture; we probably 
            # still want the option to look for both.
            relpath = a_bzrdir._control_files._escape(name)
            store = TextStore(a_bzrdir._control_files._transport.clone(relpath),
                              prefixed=prefixed, compressed=compressed,
                              dir_mode=dir_mode,
                              file_mode=file_mode)
            #if self._transport.should_cache():
            #    cache_path = os.path.join(self.cache_root, name)
            #    os.mkdir(cache_path)
            #    store = bzrlib.store.CachedStore(store, cache_path)
            return store

        # not broken out yet because the controlweaves|inventory_store
        # and text_store | weave_store bits are still different.
        if isinstance(_format, RepositoryFormat4):
            # cannot remove these - there is still no consistent api 
            # which allows access to this old info.
            self.inventory_store = get_store('inventory-store')
            text_store = get_store('text-store')
        super(AllInOneRepository, self).__init__(_format, a_bzrdir, a_bzrdir._control_files, _revision_store, control_store, text_store)


class MetaDirRepository(Repository):
    """Repositories in the new meta-dir layout."""

    def __init__(self, _format, a_bzrdir, control_files, _revision_store, control_store, text_store):
        super(MetaDirRepository, self).__init__(_format,
                                                a_bzrdir,
                                                control_files,
                                                _revision_store,
                                                control_store,
                                                text_store)

        dir_mode = self.control_files._dir_mode
        file_mode = self.control_files._file_mode

        def get_weave(name, prefixed=False):
            if name:
                name = safe_unicode(name)
            else:
                name = ''
            relpath = self.control_files._escape(name)
            weave_transport = self.control_files._transport.clone(relpath)
            ws = WeaveStore(weave_transport, prefixed=prefixed,
                            dir_mode=dir_mode,
                            file_mode=file_mode)
            if self.control_files._transport.should_cache():
                ws.enable_cache = True
            return ws


class KnitRepository(MetaDirRepository):
    """Knit format repository."""

    @needs_read_lock
    def all_revision_ids(self):
        """See Repository.all_revision_ids()."""
        return self._revision_store.all_revision_ids(self.get_transaction())


class RepositoryFormat(object):
    """A repository format.

    Formats provide three things:
     * An initialization routine to construct repository data on disk.
     * a format string which is used when the BzrDir supports versioned
       children.
     * an open routine which returns a Repository instance.

    Formats are placed in an dict by their format string for reference 
    during opening. These should be subclasses of RepositoryFormat
    for consistency.

    Once a format is deprecated, just deprecate the initialize and open
    methods on the format class. Do not deprecate the object, as the 
    object will be created every system load.

    Common instance attributes:
    _matchingbzrdir - the bzrdir format that the repository format was
    originally written to work with. This can be used if manually
    constructing a bzrdir and repository, or more commonly for test suite
    parameterisation.
    """

    _default_format = None
    """The default format used for new repositories."""

    _formats = {}
    """The known formats."""

    @classmethod
    def find_format(klass, a_bzrdir):
        """Return the format for the repository object in a_bzrdir."""
        try:
            transport = a_bzrdir.get_repository_transport(None)
            format_string = transport.get("format").read()
            return klass._formats[format_string]
        except errors.NoSuchFile:
            raise errors.NoRepositoryPresent(a_bzrdir)
        except KeyError:
            raise errors.UnknownFormatError(format_string)

    def _get_control_store(self, repo_transport, control_files):
        """Return the control store for this repository."""
        raise NotImplementedError(self._get_control_store)
    
    @classmethod
    def get_default_format(klass):
        """Return the current default format."""
        return klass._default_format

    def get_format_string(self):
        """Return the ASCII format string that identifies this format.
        
        Note that in pre format ?? repositories the format string is 
        not permitted nor written to disk.
        """
        raise NotImplementedError(self.get_format_string)

    def _get_revision_store(self, repo_transport, control_files):
        """Return the revision store object for this a_bzrdir."""
        raise NotImplementedError(self._get_revision_store)

    def _get_text_rev_store(self,
                            transport,
                            control_files,
                            name,
                            compressed=True,
                            prefixed=False,
                            serializer=None):
        """Common logic for getting a revision store for a repository.
        
        see self._get_revision_store for the subclass-overridable method to 
        get the store for a repository.
        """
        from bzrlib.store.revision.text import TextRevisionStore
        dir_mode = control_files._dir_mode
        file_mode = control_files._file_mode
        text_store =TextStore(transport.clone(name),
                              prefixed=prefixed,
                              compressed=compressed,
                              dir_mode=dir_mode,
                              file_mode=file_mode)
        _revision_store = TextRevisionStore(text_store, serializer)
        return _revision_store

    def _get_versioned_file_store(self,
                                  name,
                                  transport,
                                  control_files,
                                  prefixed=True,
                                  versionedfile_class=WeaveFile):
        weave_transport = control_files._transport.clone(name)
        dir_mode = control_files._dir_mode
        file_mode = control_files._file_mode
        return VersionedFileStore(weave_transport, prefixed=prefixed,
                                dir_mode=dir_mode,
                                file_mode=file_mode,
                                versionedfile_class=versionedfile_class)

    def initialize(self, a_bzrdir, shared=False):
        """Initialize a repository of this format in a_bzrdir.

        :param a_bzrdir: The bzrdir to put the new repository in it.
        :param shared: The repository should be initialized as a sharable one.

        This may raise UninitializableFormat if shared repository are not
        compatible the a_bzrdir.
        """

    def is_supported(self):
        """Is this format supported?

        Supported formats must be initializable and openable.
        Unsupported formats may not support initialization or committing or 
        some other features depending on the reason for not being supported.
        """
        return True

    def open(self, a_bzrdir, _found=False):
        """Return an instance of this format for the bzrdir a_bzrdir.
        
        _found is a private parameter, do not use it.
        """
        raise NotImplementedError(self.open)

    @classmethod
    def register_format(klass, format):
        klass._formats[format.get_format_string()] = format

    @classmethod
    def set_default_format(klass, format):
        klass._default_format = format

    @classmethod
    def unregister_format(klass, format):
        assert klass._formats[format.get_format_string()] is format
        del klass._formats[format.get_format_string()]


class PreSplitOutRepositoryFormat(RepositoryFormat):
    """Base class for the pre split out repository formats."""

    def initialize(self, a_bzrdir, shared=False, _internal=False):
        """Create a weave repository.
        
        TODO: when creating split out bzr branch formats, move this to a common
        base for Format5, Format6. or something like that.
        """
        from bzrlib.weavefile import write_weave_v5
        from bzrlib.weave import Weave

        if shared:
            raise errors.IncompatibleFormat(self, a_bzrdir._format)

        if not _internal:
            # always initialized when the bzrdir is.
            return self.open(a_bzrdir, _found=True)
        
        # Create an empty weave
        sio = StringIO()
        bzrlib.weavefile.write_weave_v5(Weave(), sio)
        empty_weave = sio.getvalue()

        mutter('creating repository in %s.', a_bzrdir.transport.base)
        dirs = ['revision-store', 'weaves']
        files = [('inventory.weave', StringIO(empty_weave)),
                 ]
        
        # FIXME: RBC 20060125 dont peek under the covers
        # NB: no need to escape relative paths that are url safe.
        control_files = LockableFiles(a_bzrdir.transport, 'branch-lock',
                                      TransportLock)
        control_files.create_lock()
        control_files.lock_write()
        control_files._transport.mkdir_multi(dirs,
                mode=control_files._dir_mode)
        try:
            for file, content in files:
                control_files.put(file, content)
        finally:
            control_files.unlock()
        return self.open(a_bzrdir, _found=True)

    def _get_control_store(self, repo_transport, control_files):
        """Return the control store for this repository."""
        return self._get_versioned_file_store('',
                                              repo_transport,
                                              control_files,
                                              prefixed=False)

    def _get_text_store(self, transport, control_files):
        """Get a store for file texts for this format."""
        raise NotImplementedError(self._get_text_store)

    def open(self, a_bzrdir, _found=False):
        """See RepositoryFormat.open()."""
        if not _found:
            # we are being called directly and must probe.
            raise NotImplementedError

        repo_transport = a_bzrdir.get_repository_transport(None)
        control_files = a_bzrdir._control_files
        text_store = self._get_text_store(repo_transport, control_files)
        control_store = self._get_control_store(repo_transport, control_files)
        _revision_store = self._get_revision_store(repo_transport, control_files)
        return AllInOneRepository(_format=self,
                                  a_bzrdir=a_bzrdir,
                                  _revision_store=_revision_store,
                                  control_store=control_store,
                                  text_store=text_store)


class RepositoryFormat4(PreSplitOutRepositoryFormat):
    """Bzr repository format 4.

    This repository format has:
     - flat stores
     - TextStores for texts, inventories,revisions.

    This format is deprecated: it indexes texts using a text id which is
    removed in format 5; initializationa and write support for this format
    has been removed.
    """

    def __init__(self):
        super(RepositoryFormat4, self).__init__()
        self._matchingbzrdir = bzrlib.bzrdir.BzrDirFormat4()

    def initialize(self, url, shared=False, _internal=False):
        """Format 4 branches cannot be created."""
        raise errors.UninitializableFormat(self)

    def is_supported(self):
        """Format 4 is not supported.

        It is not supported because the model changed from 4 to 5 and the
        conversion logic is expensive - so doing it on the fly was not 
        feasible.
        """
        return False

    def _get_control_store(self, repo_transport, control_files):
        """Format 4 repositories have no formal control store at this point.
        
        This will cause any control-file-needing apis to fail - this is desired.
        """
        return None
    
    def _get_revision_store(self, repo_transport, control_files):
        """See RepositoryFormat._get_revision_store()."""
        from bzrlib.xml4 import serializer_v4
        return self._get_text_rev_store(repo_transport,
                                        control_files,
                                        'revision-store',
                                        serializer=serializer_v4)

    def _get_text_store(self, transport, control_files):
        """See RepositoryFormat._get_text_store()."""


class RepositoryFormat5(PreSplitOutRepositoryFormat):
    """Bzr control format 5.

    This repository format has:
     - weaves for file texts and inventory
     - flat stores
     - TextStores for revisions and signatures.
    """

    def __init__(self):
        super(RepositoryFormat5, self).__init__()
        self._matchingbzrdir = bzrlib.bzrdir.BzrDirFormat5()

    def _get_revision_store(self, repo_transport, control_files):
        """See RepositoryFormat._get_revision_store()."""
        """Return the revision store object for this a_bzrdir."""
        return self._get_text_rev_store(repo_transport,
                                        control_files,
                                        'revision-store',
                                        compressed=False)

    def _get_text_store(self, transport, control_files):
        """See RepositoryFormat._get_text_store()."""
        return self._get_versioned_file_store('weaves', transport, control_files, prefixed=False)


class RepositoryFormat6(PreSplitOutRepositoryFormat):
    """Bzr control format 6.

    This repository format has:
     - weaves for file texts and inventory
     - hash subdirectory based stores.
     - TextStores for revisions and signatures.
    """

    def __init__(self):
        super(RepositoryFormat6, self).__init__()
        self._matchingbzrdir = bzrlib.bzrdir.BzrDirFormat6()

    def _get_revision_store(self, repo_transport, control_files):
        """See RepositoryFormat._get_revision_store()."""
        return self._get_text_rev_store(repo_transport,
                                        control_files,
                                        'revision-store',
                                        compressed=False,
                                        prefixed=True)

    def _get_text_store(self, transport, control_files):
        """See RepositoryFormat._get_text_store()."""
        return self._get_versioned_file_store('weaves', transport, control_files)


class MetaDirRepositoryFormat(RepositoryFormat):
    """Common base class for the new repositories using the metadir layour."""

    def __init__(self):
        super(MetaDirRepositoryFormat, self).__init__()
        self._matchingbzrdir = bzrlib.bzrdir.BzrDirMetaFormat1()

    def _create_control_files(self, a_bzrdir):
        """Create the required files and the initial control_files object."""
        # FIXME: RBC 20060125 dont peek under the covers
        # NB: no need to escape relative paths that are url safe.
        repository_transport = a_bzrdir.get_repository_transport(self)
        control_files = LockableFiles(repository_transport, 'lock', LockDir)
        control_files.create_lock()
        return control_files

    def _upload_blank_content(self, a_bzrdir, dirs, files, utf8_files, shared):
        """Upload the initial blank content."""
        control_files = self._create_control_files(a_bzrdir)
        control_files.lock_write()
        try:
            control_files._transport.mkdir_multi(dirs,
                    mode=control_files._dir_mode)
            for file, content in files:
                control_files.put(file, content)
            for file, content in utf8_files:
                control_files.put_utf8(file, content)
            if shared == True:
                control_files.put_utf8('shared-storage', '')
        finally:
            control_files.unlock()


class RepositoryFormat7(MetaDirRepositoryFormat):
    """Bzr repository 7.

    This repository format has:
     - weaves for file texts and inventory
     - hash subdirectory based stores.
     - TextStores for revisions and signatures.
     - a format marker of its own
     - an optional 'shared-storage' flag
     - an optional 'no-working-trees' flag
    """

    def _get_control_store(self, repo_transport, control_files):
        """Return the control store for this repository."""
        return self._get_versioned_file_store('',
                                              repo_transport,
                                              control_files,
                                              prefixed=False)

    def get_format_string(self):
        """See RepositoryFormat.get_format_string()."""
        return "Bazaar-NG Repository format 7"

    def _get_revision_store(self, repo_transport, control_files):
        """See RepositoryFormat._get_revision_store()."""
        return self._get_text_rev_store(repo_transport,
                                        control_files,
                                        'revision-store',
                                        compressed=False,
                                        prefixed=True,
                                        )

    def _get_text_store(self, transport, control_files):
        """See RepositoryFormat._get_text_store()."""
        return self._get_versioned_file_store('weaves',
                                              transport,
                                              control_files)

    def initialize(self, a_bzrdir, shared=False):
        """Create a weave repository.

        :param shared: If true the repository will be initialized as a shared
                       repository.
        """
        from bzrlib.weavefile import write_weave_v5
        from bzrlib.weave import Weave

        # Create an empty weave
        sio = StringIO()
        bzrlib.weavefile.write_weave_v5(Weave(), sio)
        empty_weave = sio.getvalue()

        mutter('creating repository in %s.', a_bzrdir.transport.base)
        dirs = ['revision-store', 'weaves']
        files = [('inventory.weave', StringIO(empty_weave)), 
                 ]
        utf8_files = [('format', self.get_format_string())]
 
        self._upload_blank_content(a_bzrdir, dirs, files, utf8_files, shared)
        return self.open(a_bzrdir=a_bzrdir, _found=True)

    def open(self, a_bzrdir, _found=False, _override_transport=None):
        """See RepositoryFormat.open().
        
        :param _override_transport: INTERNAL USE ONLY. Allows opening the
                                    repository at a slightly different url
                                    than normal. I.e. during 'upgrade'.
        """
        if not _found:
            format = RepositoryFormat.find_format(a_bzrdir)
            assert format.__class__ ==  self.__class__
        if _override_transport is not None:
            repo_transport = _override_transport
        else:
            repo_transport = a_bzrdir.get_repository_transport(None)
        control_files = LockableFiles(repo_transport, 'lock', LockDir)
        text_store = self._get_text_store(repo_transport, control_files)
        control_store = self._get_control_store(repo_transport, control_files)
        _revision_store = self._get_revision_store(repo_transport, control_files)
        return MetaDirRepository(_format=self,
                                 a_bzrdir=a_bzrdir,
                                 control_files=control_files,
                                 _revision_store=_revision_store,
                                 control_store=control_store,
                                 text_store=text_store)


class RepositoryFormatKnit1(MetaDirRepositoryFormat):
    """Bzr repository knit format 1.

    This repository format has:
     - knits for file texts and inventory
     - hash subdirectory based stores.
     - knits for revisions and signatures
     - TextStores for revisions and signatures.
     - a format marker of its own
     - an optional 'shared-storage' flag
     - an optional 'no-working-trees' flag
     - a LockDir lock
    """

    def _get_control_store(self, repo_transport, control_files):
        """Return the control store for this repository."""
        return self._get_versioned_file_store('',
                                              repo_transport,
                                              control_files,
                                              prefixed=False,
                                              versionedfile_class=KnitVersionedFile)

    def get_format_string(self):
        """See RepositoryFormat.get_format_string()."""
        return "Bazaar-NG Knit Repository Format 1"

    def _get_revision_store(self, repo_transport, control_files):
        """See RepositoryFormat._get_revision_store()."""
        from bzrlib.store.revision.knit import KnitRevisionStore
        versioned_file_store = VersionedFileStore(
            repo_transport,
            file_mode = control_files._file_mode,
            prefixed=False,
            precious=True,
            versionedfile_class=KnitVersionedFile)
        return KnitRevisionStore(versioned_file_store)

    def _get_text_store(self, transport, control_files):
        """See RepositoryFormat._get_text_store()."""
        return self._get_versioned_file_store('knits',
                                              transport,
                                              control_files,
                                              versionedfile_class=KnitVersionedFile)

    def initialize(self, a_bzrdir, shared=False):
        """Create a knit format 1 repository.

        :param shared: If true the repository will be initialized as a shared
                       repository.
        XXX NOTE that this current uses a Weave for testing and will become 
            A Knit in due course.
        """
        from bzrlib.weavefile import write_weave_v5
        from bzrlib.weave import Weave

        # Create an empty weave
        sio = StringIO()
        bzrlib.weavefile.write_weave_v5(Weave(), sio)
        empty_weave = sio.getvalue()

        mutter('creating repository in %s.', a_bzrdir.transport.base)
        dirs = ['revision-store', 'knits', 'control']
        files = [('control/inventory.weave', StringIO(empty_weave)), 
                 ]
        utf8_files = [('format', self.get_format_string())]
        
        self._upload_blank_content(a_bzrdir, dirs, files, utf8_files, shared)
        repo_transport = a_bzrdir.get_repository_transport(None)
        control_files = LockableFiles(repo_transport, 'lock', LockDir)
        control_store = self._get_control_store(repo_transport, control_files)
        transaction = bzrlib.transactions.PassThroughTransaction()
        # trigger a write of the inventory store.
        control_store.get_weave_or_empty('inventory', transaction)
        _revision_store = self._get_revision_store(repo_transport, control_files)
        _revision_store.has_revision_id('A', transaction)
        _revision_store.get_signature_file(transaction)
        return self.open(a_bzrdir=a_bzrdir, _found=True)

    def open(self, a_bzrdir, _found=False, _override_transport=None):
        """See RepositoryFormat.open().
        
        :param _override_transport: INTERNAL USE ONLY. Allows opening the
                                    repository at a slightly different url
                                    than normal. I.e. during 'upgrade'.
        """
        if not _found:
            format = RepositoryFormat.find_format(a_bzrdir)
            assert format.__class__ ==  self.__class__
        if _override_transport is not None:
            repo_transport = _override_transport
        else:
            repo_transport = a_bzrdir.get_repository_transport(None)
        control_files = LockableFiles(repo_transport, 'lock', LockDir)
        text_store = self._get_text_store(repo_transport, control_files)
        control_store = self._get_control_store(repo_transport, control_files)
        _revision_store = self._get_revision_store(repo_transport, control_files)
        return KnitRepository(_format=self,
                              a_bzrdir=a_bzrdir,
                              control_files=control_files,
                              _revision_store=_revision_store,
                              control_store=control_store,
                              text_store=text_store)


# formats which have no format string are not discoverable
# and not independently creatable, so are not registered.
_default_format = RepositoryFormat7()
RepositoryFormat.register_format(_default_format)
RepositoryFormat.register_format(RepositoryFormatKnit1())
RepositoryFormat.set_default_format(_default_format)
_legacy_formats = [RepositoryFormat4(),
                   RepositoryFormat5(),
                   RepositoryFormat6()]


class InterRepository(InterObject):
    """This class represents operations taking place between two repositories.

    Its instances have methods like copy_content and fetch, and contain
    references to the source and target repositories these operations can be 
    carried out on.

    Often we will provide convenience methods on 'repository' which carry out
    operations with another repository - they will always forward to
    InterRepository.get(other).method_name(parameters).
    """

    _optimisers = set()
    """The available optimised InterRepository types."""

    @needs_write_lock
    def copy_content(self, revision_id=None, basis=None):
        """Make a complete copy of the content in self into destination.
        
        This is a destructive operation! Do not use it on existing 
        repositories.

        :param revision_id: Only copy the content needed to construct
                            revision_id and its parents.
        :param basis: Copy the needed data preferentially from basis.
        """
        try:
            self.target.set_make_working_trees(self.source.make_working_trees())
        except NotImplementedError:
            pass
        # grab the basis available data
        if basis is not None:
            self.target.fetch(basis, revision_id=revision_id)
        # but dont bother fetching if we have the needed data now.
        if (revision_id not in (None, NULL_REVISION) and 
            self.target.has_revision(revision_id)):
            return
        self.target.fetch(self.source, revision_id=revision_id)

    def _double_lock(self, lock_source, lock_target):
        """Take out too locks, rolling back the first if the second throws."""
        lock_source()
        try:
            lock_target()
        except Exception:
            # we want to ensure that we don't leave source locked by mistake.
            # and any error on target should not confuse source.
            self.source.unlock()
            raise

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None):
        """Fetch the content required to construct revision_id.

        The content is copied from source to target.

        :param revision_id: if None all content is copied, if NULL_REVISION no
                            content is copied.
        :param pb: optional progress bar to use for progress reports. If not
                   provided a default one will be created.

        Returns the copied revision count and the failed revisions in a tuple:
        (copied, failures).
        """
        from bzrlib.fetch import GenericRepoFetcher
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target, self.target._format)
        f = GenericRepoFetcher(to_repository=self.target,
                               from_repository=self.source,
                               last_revision=revision_id,
                               pb=pb)
        return f.count_copied, f.failed_revisions

    def lock_read(self):
        """Take out a logical read lock.

        This will lock the source branch and the target branch. The source gets
        a read lock and the target a read lock.
        """
        self._double_lock(self.source.lock_read, self.target.lock_read)

    def lock_write(self):
        """Take out a logical write lock.

        This will lock the source branch and the target branch. The source gets
        a read lock and the target a write lock.
        """
        self._double_lock(self.source.lock_read, self.target.lock_write)

    @needs_read_lock
    def missing_revision_ids(self, revision_id=None):
        """Return the revision ids that source has that target does not.
        
        These are returned in topological order.

        :param revision_id: only return revision ids included by this
                            revision_id.
        """
        # generic, possibly worst case, slow code path.
        target_ids = set(self.target.all_revision_ids())
        if revision_id is not None:
            source_ids = self.source.get_ancestry(revision_id)
            assert source_ids.pop(0) == None
        else:
            source_ids = self.source.all_revision_ids()
        result_set = set(source_ids).difference(target_ids)
        # this may look like a no-op: its not. It preserves the ordering
        # other_ids had while only returning the members from other_ids
        # that we've decided we need.
        return [rev_id for rev_id in source_ids if rev_id in result_set]

    def unlock(self):
        """Release the locks on source and target."""
        try:
            self.target.unlock()
        finally:
            self.source.unlock()


class InterWeaveRepo(InterRepository):
    """Optimised code paths between Weave based repositories."""

    _matching_repo_format = _default_format
    """Repository format for testing with."""

    @staticmethod
    def is_compatible(source, target):
        """Be compatible with known Weave formats.
        
        We dont test for the stores being of specific types becase that
        could lead to confusing results, and there is no need to be 
        overly general.
        """
        try:
            return (isinstance(source._format, (RepositoryFormat5,
                                                RepositoryFormat6,
                                                RepositoryFormat7)) and
                    isinstance(target._format, (RepositoryFormat5,
                                                RepositoryFormat6,
                                                RepositoryFormat7)))
        except AttributeError:
            return False
    
    @needs_write_lock
    def copy_content(self, revision_id=None, basis=None):
        """See InterRepository.copy_content()."""
        # weave specific optimised path:
        if basis is not None:
            # copy the basis in, then fetch remaining data.
            basis.copy_content_into(self.target, revision_id)
            # the basis copy_content_into could misset this.
            try:
                self.target.set_make_working_trees(self.source.make_working_trees())
            except NotImplementedError:
                pass
            self.target.fetch(self.source, revision_id=revision_id)
        else:
            try:
                self.target.set_make_working_trees(self.source.make_working_trees())
            except NotImplementedError:
                pass
            # FIXME do not peek!
            if self.source.control_files._transport.listable():
                pb = bzrlib.ui.ui_factory.nested_progress_bar()
                try:
                    self.target.weave_store.copy_all_ids(
                        self.source.weave_store,
                        pb=pb,
                        from_transaction=self.source.get_transaction(),
                        to_transaction=self.target.get_transaction())
                    pb.update('copying inventory', 0, 1)
                    self.target.control_weaves.copy_multi(
                        self.source.control_weaves, ['inventory'],
                        from_transaction=self.source.get_transaction(),
                        to_transaction=self.target.get_transaction())
                    self.target._revision_store.text_store.copy_all_ids(
                        self.source._revision_store.text_store,
                        pb=pb)
                finally:
                    pb.finished()
            else:
                self.target.fetch(self.source, revision_id=revision_id)

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None):
        """See InterRepository.fetch()."""
        from bzrlib.fetch import GenericRepoFetcher
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target, self.target._format)
        f = GenericRepoFetcher(to_repository=self.target,
                               from_repository=self.source,
                               last_revision=revision_id,
                               pb=pb)
        return f.count_copied, f.failed_revisions

    @needs_read_lock
    def missing_revision_ids(self, revision_id=None):
        """See InterRepository.missing_revision_ids()."""
        # we want all revisions to satisfy revision_id in source.
        # but we dont want to stat every file here and there.
        # we want then, all revisions other needs to satisfy revision_id 
        # checked, but not those that we have locally.
        # so the first thing is to get a subset of the revisions to 
        # satisfy revision_id in source, and then eliminate those that
        # we do already have. 
        # this is slow on high latency connection to self, but as as this
        # disk format scales terribly for push anyway due to rewriting 
        # inventory.weave, this is considered acceptable.
        # - RBC 20060209
        if revision_id is not None:
            source_ids = self.source.get_ancestry(revision_id)
            assert source_ids.pop(0) == None
        else:
            source_ids = self.source._all_possible_ids()
        source_ids_set = set(source_ids)
        # source_ids is the worst possible case we may need to pull.
        # now we want to filter source_ids against what we actually
        # have in target, but dont try to check for existence where we know
        # we do not have a revision as that would be pointless.
        target_ids = set(self.target._all_possible_ids())
        possibly_present_revisions = target_ids.intersection(source_ids_set)
        actually_present_revisions = set(self.target._eliminate_revisions_not_present(possibly_present_revisions))
        required_revisions = source_ids_set.difference(actually_present_revisions)
        required_topo_revisions = [rev_id for rev_id in source_ids if rev_id in required_revisions]
        if revision_id is not None:
            # we used get_ancestry to determine source_ids then we are assured all
            # revisions referenced are present as they are installed in topological order.
            # and the tip revision was validated by get_ancestry.
            return required_topo_revisions
        else:
            # if we just grabbed the possibly available ids, then 
            # we only have an estimate of whats available and need to validate
            # that against the revision records.
            return self.source._eliminate_revisions_not_present(required_topo_revisions)


class InterKnitRepo(InterRepository):
    """Optimised code paths between Knit based repositories."""

    _matching_repo_format = RepositoryFormatKnit1()
    """Repository format for testing with."""

    @staticmethod
    def is_compatible(source, target):
        """Be compatible with known Knit formats.
        
        We dont test for the stores being of specific types becase that
        could lead to confusing results, and there is no need to be 
        overly general.
        """
        try:
            return (isinstance(source._format, (RepositoryFormatKnit1)) and
                    isinstance(target._format, (RepositoryFormatKnit1)))
        except AttributeError:
            return False

    @needs_write_lock
    def fetch(self, revision_id=None, pb=None):
        """See InterRepository.fetch()."""
        from bzrlib.fetch import KnitRepoFetcher
        mutter("Using fetch logic to copy between %s(%s) and %s(%s)",
               self.source, self.source._format, self.target, self.target._format)
        f = KnitRepoFetcher(to_repository=self.target,
                            from_repository=self.source,
                            last_revision=revision_id,
                            pb=pb)
        return f.count_copied, f.failed_revisions

    @needs_read_lock
    def missing_revision_ids(self, revision_id=None):
        """See InterRepository.missing_revision_ids()."""
        if revision_id is not None:
            source_ids = self.source.get_ancestry(revision_id)
            assert source_ids.pop(0) == None
        else:
            source_ids = self.source._all_possible_ids()
        source_ids_set = set(source_ids)
        # source_ids is the worst possible case we may need to pull.
        # now we want to filter source_ids against what we actually
        # have in target, but dont try to check for existence where we know
        # we do not have a revision as that would be pointless.
        target_ids = set(self.target._all_possible_ids())
        possibly_present_revisions = target_ids.intersection(source_ids_set)
        actually_present_revisions = set(self.target._eliminate_revisions_not_present(possibly_present_revisions))
        required_revisions = source_ids_set.difference(actually_present_revisions)
        required_topo_revisions = [rev_id for rev_id in source_ids if rev_id in required_revisions]
        if revision_id is not None:
            # we used get_ancestry to determine source_ids then we are assured all
            # revisions referenced are present as they are installed in topological order.
            # and the tip revision was validated by get_ancestry.
            return required_topo_revisions
        else:
            # if we just grabbed the possibly available ids, then 
            # we only have an estimate of whats available and need to validate
            # that against the revision records.
            return self.source._eliminate_revisions_not_present(required_topo_revisions)

InterRepository.register_optimiser(InterWeaveRepo)
InterRepository.register_optimiser(InterKnitRepo)


class RepositoryTestProviderAdapter(object):
    """A tool to generate a suite testing multiple repository formats at once.

    This is done by copying the test once for each transport and injecting
    the transport_server, transport_readonly_server, and bzrdir_format and
    repository_format classes into each copy. Each copy is also given a new id()
    to make it easy to identify.
    """

    def __init__(self, transport_server, transport_readonly_server, formats):
        self._transport_server = transport_server
        self._transport_readonly_server = transport_readonly_server
        self._formats = formats
    
    def adapt(self, test):
        result = TestSuite()
        for repository_format, bzrdir_format in self._formats:
            new_test = deepcopy(test)
            new_test.transport_server = self._transport_server
            new_test.transport_readonly_server = self._transport_readonly_server
            new_test.bzrdir_format = bzrdir_format
            new_test.repository_format = repository_format
            def make_new_test_id():
                new_id = "%s(%s)" % (new_test.id(), repository_format.__class__.__name__)
                return lambda: new_id
            new_test.id = make_new_test_id()
            result.addTest(new_test)
        return result


class InterRepositoryTestProviderAdapter(object):
    """A tool to generate a suite testing multiple inter repository formats.

    This is done by copying the test once for each interrepo provider and injecting
    the transport_server, transport_readonly_server, repository_format and 
    repository_to_format classes into each copy.
    Each copy is also given a new id() to make it easy to identify.
    """

    def __init__(self, transport_server, transport_readonly_server, formats):
        self._transport_server = transport_server
        self._transport_readonly_server = transport_readonly_server
        self._formats = formats
    
    def adapt(self, test):
        result = TestSuite()
        for interrepo_class, repository_format, repository_format_to in self._formats:
            new_test = deepcopy(test)
            new_test.transport_server = self._transport_server
            new_test.transport_readonly_server = self._transport_readonly_server
            new_test.interrepo_class = interrepo_class
            new_test.repository_format = repository_format
            new_test.repository_format_to = repository_format_to
            def make_new_test_id():
                new_id = "%s(%s)" % (new_test.id(), interrepo_class.__name__)
                return lambda: new_id
            new_test.id = make_new_test_id()
            result.addTest(new_test)
        return result

    @staticmethod
    def default_test_list():
        """Generate the default list of interrepo permutations to test."""
        result = []
        # test the default InterRepository between format 6 and the current 
        # default format.
        # XXX: robertc 20060220 reinstate this when there are two supported
        # formats which do not have an optimal code path between them.
        result.append((InterRepository,
                       RepositoryFormat6(),
                       RepositoryFormatKnit1()))
        for optimiser in InterRepository._optimisers:
            result.append((optimiser,
                           optimiser._matching_repo_format,
                           optimiser._matching_repo_format
                           ))
        # if there are specific combinations we want to use, we can add them 
        # here.
        return result


class CopyConverter(object):
    """A repository conversion tool which just performs a copy of the content.
    
    This is slow but quite reliable.
    """

    def __init__(self, target_format):
        """Create a CopyConverter.

        :param target_format: The format the resulting repository should be.
        """
        self.target_format = target_format
        
    def convert(self, repo, pb):
        """Perform the conversion of to_convert, giving feedback via pb.

        :param to_convert: The disk object to convert.
        :param pb: a progress bar to use for progress information.
        """
        self.pb = pb
        self.count = 0
        self.total = 3
        # this is only useful with metadir layouts - separated repo content.
        # trigger an assertion if not such
        repo._format.get_format_string()
        self.repo_dir = repo.bzrdir
        self.step('Moving repository to repository.backup')
        self.repo_dir.transport.move('repository', 'repository.backup')
        backup_transport =  self.repo_dir.transport.clone('repository.backup')
        self.source_repo = repo._format.open(self.repo_dir,
            _found=True,
            _override_transport=backup_transport)
        self.step('Creating new repository')
        converted = self.target_format.initialize(self.repo_dir,
                                                  self.source_repo.is_shared())
        converted.lock_write()
        try:
            self.step('Copying content into repository.')
            self.source_repo.copy_content_into(converted)
        finally:
            converted.unlock()
        self.step('Deleting old repository content.')
        self.repo_dir.transport.delete_tree('repository.backup')
        self.pb.note('repository converted')

    def step(self, message):
        """Update the pb by a step."""
        self.count +=1
        self.pb.update(message, self.count, self.total)