convert/subversion: work around memory leak in svn's python bindings

The svn.ra.get_log wrapper attaches the hash of changed paths for every
log entry to a global memory pool, so memory consumption increases
rapidly, with no way to free it.

Our workaround is to call this function in a child process, and feed
its results back over a pipe.  The memory consumption of the child still
grows huge (hundreds of megabytes), but at least it goes away once the
reading-the-log phase is done.

hgext/convert/subversion.py

@@ -1,620 +1,664
 # Subversion 1.4/1.5 Python API backend
 #
 # Copyright(C) 2007 Daniel Holth et al
 #
 # Configuration options:
 #
 # convert.svn.trunk
 #   Relative path to the trunk (default: "trunk")
 # convert.svn.branches
 #   Relative path to tree of branches (default: "branches")
 #
 # Set these in a hgrc, or on the command line as follows:
 #
 #   hg convert --config convert.svn.trunk=wackoname [...]
 
 import pprint
 import locale
-
+import os
+import cPickle as pickle
 from mercurial import util
 
 # Subversion stuff. Works best with very recent Python SVN bindings
 # e.g. SVN 1.5 or backports. Thanks to the bzr folks for enhancing
 # these bindings.
 
 from cStringIO import StringIO
 
 from common import NoRepo, commit, converter_source
 
 try:
     from svn.core import SubversionException, Pool
     import svn.core
     import svn.ra
     import svn.delta
     import svn
     import transport
 except ImportError:
     pass
 
 class CompatibilityException(Exception): pass
 
+class changedpath(object):
+    def __init__(self, p):
+        self.copyfrom_path = p.copyfrom_path
+        self.copyfrom_rev = p.copyfrom_rev
+        self.action = p.action
+
 # SVN conversion code stolen from bzr-svn and tailor
 class convert_svn(converter_source):
     def __init__(self, ui, url, rev=None):
         super(convert_svn, self).__init__(ui, url, rev=rev)
 
         try:
             SubversionException
         except NameError:
             msg = 'subversion python bindings could not be loaded\n'
             ui.warn(msg)
             raise NoRepo(msg)
 
         self.encoding = locale.getpreferredencoding()
         self.lastrevs = {}
 
         latest = None
         if rev:
             try:
                 latest = int(rev)
             except ValueError:
                 raise util.Abort('svn: revision %s is not an integer' % rev)
         try:
             # Support file://path@rev syntax. Useful e.g. to convert
             # deleted branches.
             at = url.rfind('@')
             if at >= 0:
                 latest = int(url[at+1:])
                 url = url[:at]
         except ValueError, e:
             pass
         self.url = url
         self.encoding = 'UTF-8' # Subversion is always nominal UTF-8
         try:
-            self.transport = transport.SvnRaTransport(url = url)
+            self.transport = transport.SvnRaTransport(url=url)
             self.ra = self.transport.ra
-            self.ctx = svn.client.create_context()
+            self.ctx = self.transport.client
             self.base = svn.ra.get_repos_root(self.ra)
             self.module = self.url[len(self.base):]
             self.modulemap = {} # revision, module
             self.commits = {}
             self.files = {}
             self.uuid = svn.ra.get_uuid(self.ra).decode(self.encoding)
         except SubversionException, e:
             raise NoRepo("couldn't open SVN repo %s" % url)
 
         try:
             self.get_blacklist()
         except IOError, e:
             pass
 
         self.last_changed = self.latest(self.module, latest)
 
         self.head = self.revid(self.last_changed)
 
     def setrevmap(self, revmap):
         lastrevs = {}
         for revid in revmap.keys():
             uuid, module, revnum = self.revsplit(revid)
             lastrevnum = lastrevs.setdefault(module, revnum)
             if revnum > lastrevnum:
                 lastrevs[module] = revnum
         self.lastrevs = lastrevs
 
     def exists(self, path, optrev):
         try:
             return svn.client.ls(self.url.rstrip('/') + '/' + path,
                                  optrev, False, self.ctx)
         except SubversionException, err:
             return []
 
     def getheads(self):
         # detect standard /branches, /tags, /trunk layout
         optrev = svn.core.svn_opt_revision_t()
         optrev.kind = svn.core.svn_opt_revision_number
         optrev.value.number = self.last_changed
         rpath = self.url.strip('/')
         cfgtrunk = self.ui.config('convert', 'svn.trunk')
         cfgbranches = self.ui.config('convert', 'svn.branches')
         trunk = (cfgtrunk or 'trunk').strip('/')
         branches = (cfgbranches or 'branches').strip('/')
         if self.exists(trunk, optrev) and self.exists(branches, optrev):
             self.ui.note('found trunk at %r and branches at %r\n' %
                          (trunk, branches))
             oldmodule = self.module
             self.module += '/' + trunk
             lt = self.latest(self.module, self.last_changed)
             self.head = self.revid(lt)
             self.heads = [self.head]
             branchnames = svn.client.ls(rpath + '/' + branches, optrev, False,
                                         self.ctx)
             for branch in branchnames.keys():
                 if oldmodule:
                     module = '/' + oldmodule + '/' + branches + '/' + branch
                 else:
                     module = '/' + branches + '/' + branch
                 brevnum = self.latest(module, self.last_changed)
                 brev = self.revid(brevnum, module)
                 self.ui.note('found branch %s at %d\n' % (branch, brevnum))
                 self.heads.append(brev)
         elif cfgtrunk or cfgbranches:
             raise util.Abort(_('trunk/branch layout expected, '
                                'but not found'))
         else:
             self.ui.note('working with one branch\n')
             self.heads = [self.head]
         return self.heads
 
     def getfile(self, file, rev):
         data, mode = self._getfile(file, rev)
         self.modecache[(file, rev)] = mode
         return data
 
     def getmode(self, file, rev):        
         return self.modecache[(file, rev)]
 
     def getchanges(self, rev):
         self.modecache = {}
         files = self.files[rev]
         cl = files
         cl.sort()
         # caller caches the result, so free it here to release memory
         del self.files[rev]
         return cl
 
     def getcommit(self, rev):
         if rev not in self.commits:
             uuid, module, revnum = self.revsplit(rev)
             self.module = module
             self.reparent(module)
             stop = self.lastrevs.get(module, 0)
             self._fetch_revisions(from_revnum=revnum, to_revnum=stop)
         commit = self.commits[rev]
         # caller caches the result, so free it here to release memory
         del self.commits[rev]
         return commit
 
+    def get_log(self, paths, start, end, limit=0, discover_changed_paths=True,
+                strict_node_history=False):
+        '''wrapper for svn.ra.get_log.
+        on a large repository, svn.ra.get_log pins huge amounts of
+        memory that cannot be recovered.  work around it by forking
+        and writing results over a pipe.'''
+
+        def child(fp):
+            protocol = -1
+            def receiver(orig_paths, revnum, author, date, message, pool):
+                if orig_paths is not None:
+                    for k, v in orig_paths.iteritems():
+                        orig_paths[k] = changedpath(v)
+                pickle.dump((orig_paths, revnum, author, date, message),
+                            fp, protocol)
+
+            try:
+                # Use an ra of our own so that our parent can consume
+                # our results without confusing the server.
+                t = transport.SvnRaTransport(url=self.url)
+                svn.ra.get_log(t.ra, paths, start, end, limit,
+                               discover_changed_paths,
+                               strict_node_history,
+                               receiver)
+            except SubversionException, (_, num):
+                pickle.dump(num, fp, protocol)
+            else:
+                pickle.dump(None, fp, protocol)
+            fp.close()
+
+        def parent(fp):
+            while True:
+                entry = pickle.load(fp)
+                try:
+                    orig_paths, revnum, author, date, message = entry
+                except:
+                    if entry is None:
+                        break
+                    raise SubversionException("child raised exception", entry)
+                yield entry
+
+        rfd, wfd = os.pipe()
+        pid = os.fork()
+        if pid:
+            os.close(wfd)
+            for p in parent(os.fdopen(rfd, 'rb')):
+                yield p
+            ret = os.waitpid(pid, 0)[1]
+            if ret:
+                raise util.Abort(_('get_log %s') % util.explain_exit(ret))
+        else:
+            os.close(rfd)
+            child(os.fdopen(wfd, 'wb'))
+            os._exit(0)
+
     def gettags(self):
         tags = {}
-        def parselogentry(*arg, **args):
-            orig_paths, revnum, author, date, message, pool = arg
+        for entry in self.get_log(['/tags'], 0, self.revnum(self.head)):
+            orig_paths, revnum, author, date, message = entry
             for path in orig_paths:
                 if not path.startswith('/tags/'):
                     continue
                 ent = orig_paths[path]
                 source = ent.copyfrom_path
                 rev = ent.copyfrom_rev
                 tag = path.split('/', 2)[2]
                 tags[tag] = self.revid(rev, module=source)
-
-        start = self.revnum(self.head)
-        try:
-            svn.ra.get_log(self.ra, ['/tags'], 0, start, 0, True, False,
-                           parselogentry)
-            return tags
-        except SubversionException:
-            self.ui.note('no tags found at revision %d\n' % start)
-            return {}
+        return tags
 
     # -- helper functions --
 
     def revid(self, revnum, module=None):
         if not module:
             module = self.module
         return (u"svn:%s%s@%s" % (self.uuid, module, revnum)).decode(self.encoding)
 
     def revnum(self, rev):
         return int(rev.split('@')[-1])
 
     def revsplit(self, rev):
         url, revnum = rev.encode(self.encoding).split('@', 1)
         revnum = int(revnum)
         parts = url.split('/', 1)
         uuid = parts.pop(0)[4:]
         mod = ''
         if parts:
             mod = '/' + parts[0]
         return uuid, mod, revnum
 
     def latest(self, path, stop=0):
         'find the latest revision affecting path, up to stop'
         if not stop:
             stop = svn.ra.get_latest_revnum(self.ra)
         try:
             self.reparent('')
             dirent = svn.ra.stat(self.ra, path.strip('/'), stop)
             self.reparent(self.module)
         except SubversionException:
             dirent = None
         if not dirent:
             print self.base, path
             raise util.Abort('%s not found up to revision %d' % (path, stop))
 
         return dirent.created_rev
 
     def get_blacklist(self):
         """Avoid certain revision numbers.
         It is not uncommon for two nearby revisions to cancel each other
         out, e.g. 'I copied trunk into a subdirectory of itself instead
         of making a branch'. The converted repository is significantly
         smaller if we ignore such revisions."""
         self.blacklist = set()
         blacklist = self.blacklist
         for line in file("blacklist.txt", "r"):
             if not line.startswith("#"):
                 try:
                     svn_rev = int(line.strip())
                     blacklist.add(svn_rev)
                 except ValueError, e:
                     pass # not an integer or a comment
 
     def is_blacklisted(self, svn_rev):
         return svn_rev in self.blacklist
 
     def reparent(self, module):
         svn_url = self.base + module
         self.ui.debug("reparent to %s\n" % svn_url.encode(self.encoding))
         svn.ra.reparent(self.ra, svn_url.encode(self.encoding))
 
     def _fetch_revisions(self, from_revnum = 0, to_revnum = 347):
         def get_entry_from_path(path, module=self.module):
             # Given the repository url of this wc, say
             #   "http://server/plone/CMFPlone/branches/Plone-2_0-branch"
             # extract the "entry" portion (a relative path) from what
             # svn log --xml says, ie
             #   "/CMFPlone/branches/Plone-2_0-branch/tests/PloneTestCase.py"
             # that is to say "tests/PloneTestCase.py"
 
             if path.startswith(module):
                 relative = path[len(module):]
                 if relative.startswith('/'):
                     return relative[1:]
                 else:
                     return relative
 
             # The path is outside our tracked tree...
             self.ui.debug('Ignoring %r since it is not under %r\n' % (path, module))
             return None
 
-        received = []
-        # svn.ra.get_log requires no other calls to the ra until it completes,
-        # so we just collect the log entries and parse them afterwards
-        def receivelog(orig_paths, revnum, author, date, message, pool):
-            if self.is_blacklisted(revnum):
-                self.ui.note('skipping blacklisted revision %d\n' % revnum)
-                return
-           
-            if orig_paths is None:
-                self.ui.debug('revision %d has no entries\n' % revnum)
-                return
-
-            received.append((revnum, orig_paths.items(), author, date, message))
-
         self.child_cset = None
-        def parselogentry((revnum, orig_paths, author, date, message)):
-            self.ui.debug("parsing revision %d\n" % revnum)
+        def parselogentry(orig_paths, revnum, author, date, message):
+            self.ui.debug("parsing revision %d (%d changes)\n" %
+                          (revnum, len(orig_paths)))
 
             if revnum in self.modulemap:
                 new_module = self.modulemap[revnum]
                 if new_module != self.module:
                     self.module = new_module
                     self.reparent(self.module)
 
             copyfrom = {} # Map of entrypath, revision for finding source of deleted revisions.
             copies = {}
             entries = []
             rev = self.revid(revnum)
             parents = []
 
             # branch log might return entries for a parent we already have
             if (rev in self.commits or
                 (revnum < self.lastrevs.get(self.module, 0))):
                 return
 
             try:
                 branch = self.module.split("/")[-1]
                 if branch == 'trunk':
                     branch = ''
             except IndexError:
                 branch = None
 
+            orig_paths = orig_paths.items()
             orig_paths.sort()
             for path, ent in orig_paths:
                 # self.ui.write("path %s\n" % path)
                 if path == self.module: # Follow branching back in history
                     if ent:
                         if ent.copyfrom_path:
                             # ent.copyfrom_rev may not be the actual last revision
                             prev = self.latest(ent.copyfrom_path, ent.copyfrom_rev)
                             self.modulemap[prev] = ent.copyfrom_path
                             parents = [self.revid(prev, ent.copyfrom_path)]
                             self.ui.note('found parent of branch %s at %d: %s\n' % \
                                          (self.module, prev, ent.copyfrom_path))
                         else:
                             self.ui.debug("No copyfrom path, don't know what to do.\n")
                             # Maybe it was added and there is no more history.
                 entrypath = get_entry_from_path(path, module=self.module)
                 # self.ui.write("entrypath %s\n" % entrypath)
                 if entrypath is None:
                     # Outside our area of interest
                     self.ui.debug("boring@%s: %s\n" % (revnum, path))
                     continue
                 entry = entrypath.decode(self.encoding)
 
                 kind = svn.ra.check_path(self.ra, entrypath, revnum)
                 if kind == svn.core.svn_node_file:
                     if ent.copyfrom_path:
                         copyfrom_path = get_entry_from_path(ent.copyfrom_path)
                         if copyfrom_path:
                             self.ui.debug("Copied to %s from %s@%s\n" % (entry, copyfrom_path, ent.copyfrom_rev))
                             # It's probably important for hg that the source
                             # exists in the revision's parent, not just the
                             # ent.copyfrom_rev
                             fromkind = svn.ra.check_path(self.ra, copyfrom_path, ent.copyfrom_rev)
                             if fromkind != 0:
                                 copies[self.recode(entry)] = self.recode(copyfrom_path)
                     entries.append(self.recode(entry))
                 elif kind == 0: # gone, but had better be a deleted *file*
                     self.ui.debug("gone from %s\n" % ent.copyfrom_rev)
 
                     # if a branch is created but entries are removed in the same
                     # changeset, get the right fromrev
                     if parents:
                         uuid, old_module, fromrev = self.revsplit(parents[0])
                     else:
                         fromrev = revnum - 1
                         # might always need to be revnum - 1 in these 3 lines?
                         old_module = self.modulemap.get(fromrev, self.module)
 
                     basepath = old_module + "/" + get_entry_from_path(path, module=self.module)
                     entrypath = old_module + "/" + get_entry_from_path(path, module=self.module)
 
                     def lookup_parts(p):
                         rc = None
                         parts = p.split("/")
                         for i in range(len(parts)):
                             part = "/".join(parts[:i])
                             info = part, copyfrom.get(part, None)
                             if info[1] is not None:
                                 self.ui.debug("Found parent directory %s\n" % info[1])
                                 rc = info
                         return rc
 
                     self.ui.debug("base, entry %s %s\n" % (basepath, entrypath))
 
                     frompath, froment = lookup_parts(entrypath) or (None, revnum - 1)
 
                     # need to remove fragment from lookup_parts and replace with copyfrom_path
                     if frompath is not None:
                         self.ui.debug("munge-o-matic\n")
                         self.ui.debug(entrypath + '\n')
                         self.ui.debug(entrypath[len(frompath):] + '\n')
                         entrypath = froment.copyfrom_path + entrypath[len(frompath):]
                         fromrev = froment.copyfrom_rev
                         self.ui.debug("Info: %s %s %s %s\n" % (frompath, froment, ent, entrypath))
 
                     fromkind = svn.ra.check_path(self.ra, entrypath, fromrev)
                     if fromkind == svn.core.svn_node_file:   # a deleted file
                         entries.append(self.recode(entry))
                     elif fromkind == svn.core.svn_node_dir:
                         # print "Deleted/moved non-file:", revnum, path, ent
                         # children = self._find_children(path, revnum - 1)
                         # print "find children %s@%d from %d action %s" % (path, revnum, ent.copyfrom_rev, ent.action)
                         # Sometimes this is tricky. For example: in
                         # The Subversion Repository revision 6940 a dir
                         # was copied and one of its files was deleted 
                         # from the new location in the same commit. This
                         # code can't deal with that yet.
                         if ent.action == 'C':
                             children = self._find_children(path, fromrev)
                         else:
                             oroot = entrypath.strip('/')
                             nroot = path.strip('/')
                             children = self._find_children(oroot, fromrev)
                             children = [s.replace(oroot,nroot) for s in children]
                         # Mark all [files, not directories] as deleted.
                         for child in children:
                             # Can we move a child directory and its
                             # parent in the same commit? (probably can). Could
                             # cause problems if instead of revnum -1, 
                             # we have to look in (copyfrom_path, revnum - 1)
                             entrypath = get_entry_from_path("/" + child, module=old_module)
                             if entrypath:
                                 entry = self.recode(entrypath.decode(self.encoding))
                                 if entry in copies:
                                     # deleted file within a copy
                                     del copies[entry]
                                 else:
                                     entries.append(entry)
                     else:
                         self.ui.debug('unknown path in revision %d: %s\n' % \
                                       (revnum, path))
                 elif kind == svn.core.svn_node_dir:
                     # Should probably synthesize normal file entries
                     # and handle as above to clean up copy/rename handling.
 
                     # If the directory just had a prop change,
                     # then we shouldn't need to look for its children.
                     # Also this could create duplicate entries. Not sure
                     # whether this will matter. Maybe should make entries a set.
                     # print "Changed directory", revnum, path, ent.action, ent.copyfrom_path, ent.copyfrom_rev
                     # This will fail if a directory was copied
                     # from another branch and then some of its files
                     # were deleted in the same transaction.
                     children = self._find_children(path, revnum)
                     children.sort()
                     for child in children:
                         # Can we move a child directory and its
                         # parent in the same commit? (probably can). Could
                         # cause problems if instead of revnum -1, 
                         # we have to look in (copyfrom_path, revnum - 1)
                         entrypath = get_entry_from_path("/" + child, module=self.module)
                         # print child, self.module, entrypath
                         if entrypath:
                             # Need to filter out directories here...
                             kind = svn.ra.check_path(self.ra, entrypath, revnum)
                             if kind != svn.core.svn_node_dir:
                                 entries.append(self.recode(entrypath))
 
                     # Copies here (must copy all from source)
                     # Probably not a real problem for us if
                     # source does not exist
 
                     # Can do this with the copy command "hg copy"
                     # if ent.copyfrom_path:
                     #     copyfrom_entry = get_entry_from_path(ent.copyfrom_path.decode(self.encoding),
                     #             module=self.module)
                     #     copyto_entry = entrypath
                     #
                     #     print "copy directory", copyfrom_entry, 'to', copyto_entry
                     #
                     #     copies.append((copyfrom_entry, copyto_entry))
 
                     if ent.copyfrom_path:
                         copyfrom_path = ent.copyfrom_path.decode(self.encoding)
                         copyfrom_entry = get_entry_from_path(copyfrom_path, module=self.module)
                         if copyfrom_entry:
                             copyfrom[path] = ent
                             self.ui.debug("mark %s came from %s\n" % (path, copyfrom[path]))
 
                             # Good, /probably/ a regular copy. Really should check
                             # to see whether the parent revision actually contains
                             # the directory in question.
                             children = self._find_children(self.recode(copyfrom_path), ent.copyfrom_rev)
                             children.sort()
                             for child in children:
                                 entrypath = get_entry_from_path("/" + child, module=self.module)
                                 if entrypath:
                                     entry = entrypath.decode(self.encoding)
                                     # print "COPY COPY From", copyfrom_entry, entry
                                     copyto_path = path + entry[len(copyfrom_entry):]
                                     copyto_entry =  get_entry_from_path(copyto_path, module=self.module)
                                     # print "COPY", entry, "COPY To", copyto_entry
                                     copies[self.recode(copyto_entry)] = self.recode(entry)
                                     # copy from quux splort/quuxfile
 
             self.modulemap[revnum] = self.module # track backwards in time
             # a list of (filename, id) where id lets us retrieve the file.
             # eg in git, id is the object hash. for svn it'll be the 
             self.files[rev] = zip(entries, [rev] * len(entries))
             if not entries:
                 return
 
             # Example SVN datetime. Includes microseconds.
             # ISO-8601 conformant
             # '2007-01-04T17:35:00.902377Z'
             date = util.parsedate(date[:18] + " UTC", ["%Y-%m-%dT%H:%M:%S"])
 
             log = message and self.recode(message)
             author = author and self.recode(author) or ''
 
             cset = commit(author=author,
                           date=util.datestr(date), 
                           desc=log, 
                           parents=parents,
                           copies=copies,
                           branch=branch,
                           rev=rev.encode('utf-8'))
 
             self.commits[rev] = cset
             if self.child_cset and not self.child_cset.parents:
                 self.child_cset.parents = [rev]
             self.child_cset = cset
 
         self.ui.note('fetching revision log for "%s" from %d to %d\n' %
                      (self.module, from_revnum, to_revnum))
 
         try:
             discover_changed_paths = True
             strict_node_history = False
-            svn.ra.get_log(self.ra, [self.module], from_revnum, to_revnum, 0,
-                           discover_changed_paths, strict_node_history,
-                           receivelog)
-            self.ui.note('parsing %d log entries for "%s"\n' %
-                         (len(received), self.module))
-            for entry in received:
-                parselogentry(entry)
+            for entry in self.get_log([self.module], from_revnum, to_revnum):
+                orig_paths, revnum, author, date, message = entry
+                if self.is_blacklisted(revnum):
+                    self.ui.note('skipping blacklisted revision %d\n' % revnum)
+                    continue
+                if orig_paths is None:
+                    self.ui.debug('revision %d has no entries\n' % revnum)
+                    continue
+                parselogentry(orig_paths, revnum, author, date, message)
         except SubversionException, (_, num):
             if num == svn.core.SVN_ERR_FS_NO_SUCH_REVISION:
                 raise NoSuchRevision(branch=self, 
                     revision="Revision number %d" % to_revnum)
             raise
 
     def _getfile(self, file, rev):
         io = StringIO()
         # TODO: ra.get_file transmits the whole file instead of diffs.
         mode = ''
         try:
             revnum = self.revnum(rev)
             if self.module != self.modulemap[revnum]:
                 self.module = self.modulemap[revnum]
                 self.reparent(self.module)
             info = svn.ra.get_file(self.ra, file, revnum, io)
             if isinstance(info, list):
                 info = info[-1]
             mode = ("svn:executable" in info) and 'x' or ''
             mode = ("svn:special" in info) and 'l' or mode
         except SubversionException, e:
             notfound = (svn.core.SVN_ERR_FS_NOT_FOUND,
                 svn.core.SVN_ERR_RA_DAV_PATH_NOT_FOUND)
             if e.apr_err in notfound: # File not found
                 raise IOError()
             raise
         data = io.getvalue()
         if mode == 'l':
             link_prefix = "link "
             if data.startswith(link_prefix):
                 data = data[len(link_prefix):]
         return data, mode
 
     def _find_children(self, path, revnum):
         path = path.strip("/")
 
         def _find_children_fallback(path, revnum):
             # SWIG python bindings for getdir are broken up to at least 1.4.3
             pool = Pool()
             optrev = svn.core.svn_opt_revision_t()
             optrev.kind = svn.core.svn_opt_revision_number
             optrev.value.number = revnum
             rpath = '/'.join([self.base, path]).strip('/')
             return ['%s/%s' % (path, x) for x in svn.client.ls(rpath, optrev, True, self.ctx, pool).keys()]
 
         if hasattr(self, '_find_children_fallback'):
             return _find_children_fallback(path, revnum)
 
         self.reparent("/" + path)
         pool = Pool()
 
         children = []
         def find_children_inner(children, path, revnum = revnum):
             if hasattr(svn.ra, 'get_dir2'): # Since SVN 1.4
                 fields = 0xffffffff # Binding does not provide SVN_DIRENT_ALL
                 getdir = svn.ra.get_dir2(self.ra, path, revnum, fields, pool)
             else:
                 getdir = svn.ra.get_dir(self.ra, path, revnum, pool)
             if type(getdir) == dict:
                 # python binding for getdir is broken up to at least 1.4.3
                 raise CompatibilityException()
             dirents = getdir[0]
             if type(dirents) == int:
                 # got here once due to infinite recursion bug
                 # pprint.pprint(getdir)
                 return
             c = dirents.keys()
             c.sort()
             for child in c:
                 dirent = dirents[child]
                 if dirent.kind == svn.core.svn_node_dir:
                     find_children_inner(children, (path + "/" + child).strip("/"))
                 else:
                     children.append((path + "/" + child).strip("/"))
 
         try:
             find_children_inner(children, "")
         except CompatibilityException:
             self._find_children_fallback = True
             self.reparent(self.module)
             return _find_children_fallback(path, revnum)
 
         self.reparent(self.module)
         return [path + "/" + c for c in children]