fix 'convert' with single commit repositories

The attached patch passes the three 'convert' testcases, and also is
able to successfully convert the git.git repository.

hgext/convert/__init__.py

@@ -1,313 +1,318 b''
 # convert.py Foreign SCM converter
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
 from common import NoRepo
 from cvs import convert_cvs
 from git import convert_git
 from hg import convert_mercurial
 
 import os
 from mercurial import hg, ui, util, commands
 
 commands.norepo += " convert"
 
 converters = [convert_cvs, convert_git, convert_mercurial]
 
 def converter(ui, path):
     if not os.path.isdir(path):
         raise util.Abort("%s: not a directory" % path)
     for c in converters:
         try:
             return c(ui, path)
         except NoRepo:
             pass
     raise util.Abort("%s: unknown repository type" % path)
 
 class convert(object):
     def __init__(self, ui, source, dest, mapfile, opts):
 
         self.source = source
         self.dest = dest
         self.ui = ui
         self.opts = opts
         self.commitcache = {}
         self.mapfile = mapfile
         self.mapfilefd = None
         self.authors = {}
         self.authorfile = None
 
         self.map = {}
         try:
             origmapfile = open(self.mapfile, 'r')
             for l in origmapfile:
                 sv, dv = l[:-1].split()
                 self.map[sv] = dv
             origmapfile.close()
         except IOError:
             pass
 
         # Read first the dst author map if any
         authorfile = self.dest.authorfile()
         if authorfile and os.path.exists(authorfile):
             self.readauthormap(authorfile)
         # Extend/Override with new author map if necessary
         if opts.get('authors'):
             self.readauthormap(opts.get('authors'))
             self.authorfile = self.dest.authorfile()
 
     def walktree(self, heads):
+        '''Return a mapping that identifies the uncommitted parents of every
+        uncommitted changeset.'''
         visit = heads
         known = {}
         parents = {}
         while visit:
             n = visit.pop(0)
             if n in known or n in self.map: continue
             known[n] = 1
             self.commitcache[n] = self.source.getcommit(n)
             cp = self.commitcache[n].parents
+            parents[n] = []
             for p in cp:
-                parents.setdefault(n, []).append(p)
+                parents[n].append(p)
                 visit.append(p)
 
         return parents
 
     def toposort(self, parents):
+        '''Return an ordering such that every uncommitted changeset is
+        preceeded by all its uncommitted ancestors.'''
         visit = parents.keys()
         seen = {}
         children = {}
 
         while visit:
             n = visit.pop(0)
             if n in seen: continue
             seen[n] = 1
-            pc = 0
-            if n in parents:
-                for p in parents[n]:
-                    if p not in self.map: pc += 1
+            # Ensure that nodes without parents are present in the 'children'
+            # mapping.
+            children.setdefault(n, [])
+            for p in parents[n]:
+                if not p in self.map:
                     visit.append(p)
-                    children.setdefault(p, []).append(n)
-            if not pc: root = n
+                children.setdefault(p, []).append(n)
 
         s = []
         removed = {}
         visit = children.keys()
         while visit:
             n = visit.pop(0)
             if n in removed: continue
             dep = 0
             if n in parents:
                 for p in parents[n]:
                     if p in self.map: continue
                     if p not in removed:
                         # we're still dependent
                         visit.append(n)
                         dep = 1
                         break
 
             if not dep:
                 # all n's parents are in the list
                 removed[n] = 1
                 if n not in self.map:
                     s.append(n)
                 if n in children:
                     for c in children[n]:
                         visit.insert(0, c)
 
         if self.opts.get('datesort'):
             depth = {}
             for n in s:
                 depth[n] = 0
                 pl = [p for p in self.commitcache[n].parents
                       if p not in self.map]
                 if pl:
                     depth[n] = max([depth[p] for p in pl]) + 1
 
             s = [(depth[n], self.commitcache[n].date, n) for n in s]
             s.sort()
             s = [e[2] for e in s]
 
         return s
 
     def mapentry(self, src, dst):
         if self.mapfilefd is None:
             try:
                 self.mapfilefd = open(self.mapfile, "a")
             except IOError, (errno, strerror):
                 raise util.Abort("Could not open map file %s: %s, %s\n" % (self.mapfile, errno, strerror))
         self.map[src] = dst
         self.mapfilefd.write("%s %s\n" % (src, dst))
         self.mapfilefd.flush()
 
     def writeauthormap(self):
         authorfile = self.authorfile
         if authorfile:
            self.ui.status('Writing author map file %s\n' % authorfile)
            ofile = open(authorfile, 'w+')
            for author in self.authors:
                ofile.write("%s=%s\n" % (author, self.authors[author]))
            ofile.close()
 
     def readauthormap(self, authorfile):
         afile = open(authorfile, 'r')
         for line in afile:
             try:
                 srcauthor = line.split('=')[0].strip()
                 dstauthor = line.split('=')[1].strip()
                 if srcauthor in self.authors and dstauthor != self.authors[srcauthor]:
                     self.ui.status(
                         'Overriding mapping for author %s, was %s, will be %s\n'
                         % (srcauthor, self.authors[srcauthor], dstauthor))
                 else:
                     self.ui.debug('Mapping author %s to %s\n'
                                   % (srcauthor, dstauthor))
                     self.authors[srcauthor] = dstauthor
             except IndexError:
                 self.ui.warn(
                     'Ignoring bad line in author file map %s: %s\n'
                     % (authorfile, line))
         afile.close()
 
     def copy(self, rev):
         c = self.commitcache[rev]
         files = self.source.getchanges(rev)
 
         for f, v in files:
             try:
                 data = self.source.getfile(f, v)
             except IOError, inst:
                 self.dest.delfile(f)
             else:
                 e = self.source.getmode(f, v)
                 self.dest.putfile(f, e, data)
 
         r = [self.map[v] for v in c.parents]
         f = [f for f, v in files]
         newnode = self.dest.putcommit(f, r, c)
         self.mapentry(rev, newnode)
 
     def convert(self):
         try:
             self.ui.status("scanning source...\n")
             heads = self.source.getheads()
             parents = self.walktree(heads)
             self.ui.status("sorting...\n")
             t = self.toposort(parents)
             num = len(t)
             c = None
 
             self.ui.status("converting...\n")
             for c in t:
                 num -= 1
                 desc = self.commitcache[c].desc
                 if "\n" in desc:
                     desc = desc.splitlines()[0]
                 author = self.commitcache[c].author
                 author = self.authors.get(author, author)
                 self.commitcache[c].author = author
                 self.ui.status("%d %s\n" % (num, desc))
                 self.copy(c)
 
             tags = self.source.gettags()
             ctags = {}
             for k in tags:
                 v = tags[k]
                 if v in self.map:
                     ctags[k] = self.map[v]
 
             if c and ctags:
                 nrev = self.dest.puttags(ctags)
                 # write another hash correspondence to override the previous
                 # one so we don't end up with extra tag heads
                 if nrev:
                     self.mapentry(c, nrev)
 
             self.writeauthormap()
         finally:
             self.cleanup()
 
     def cleanup(self):
        if self.mapfilefd:
            self.mapfilefd.close()
 
 def _convert(ui, src, dest=None, mapfile=None, **opts):
     '''Convert a foreign SCM repository to a Mercurial one.
 
     Accepted source formats:
     - GIT
     - CVS
 
     Accepted destination formats:
     - Mercurial
 
     If destination isn't given, a new Mercurial repo named <src>-hg will
     be created. If <mapfile> isn't given, it will be put in a default
     location (<dest>/.hg/shamap by default)
 
     The <mapfile> is a simple text file that maps each source commit ID to
     the destination ID for that revision, like so:
     <source ID> <destination ID>
 
     If the file doesn't exist, it's automatically created.  It's updated
     on each commit copied, so convert-repo can be interrupted and can
     be run repeatedly to copy new commits.
 
     The [username mapping] file is a simple text file that maps each source
     commit author to a destination commit author. It is handy for source SCMs
     that use unix logins to identify authors (eg: CVS). One line per author
     mapping and the line format is:
     srcauthor=whatever string you want
     '''
 
     srcc = converter(ui, src)
     if not hasattr(srcc, "getcommit"):
         raise util.Abort("%s: can't read from this repo type" % src)
 
     if not dest:
         dest = src + "-hg"
         ui.status("assuming destination %s\n" % dest)
 
     # Try to be smart and initalize things when required
     if os.path.isdir(dest):
         if len(os.listdir(dest)) > 0:
             try:
                 hg.repository(ui, dest)
                 ui.status("destination %s is a Mercurial repository\n" % dest)
             except hg.RepoError:
                 raise util.Abort(
                     "destination directory %s is not empty.\n"
                     "Please specify an empty directory to be initialized\n"
                     "or an already initialized mercurial repository"
                     % dest)
         else:
             ui.status("initializing destination %s repository\n" % dest)
             hg.repository(ui, dest, create=True)
     elif os.path.exists(dest):
         raise util.Abort("destination %s exists and is not a directory" % dest)
     else:
         ui.status("initializing destination %s repository\n" % dest)
         hg.repository(ui, dest, create=True)
 
     destc = converter(ui, dest)
     if not hasattr(destc, "putcommit"):
         raise util.Abort("%s: can't write to this repo type" % src)
 
     if not mapfile:
         try:
             mapfile = destc.mapfile()
         except:
             mapfile = os.path.join(destc, "map")
 
     c = convert(ui, srcc, destc, mapfile, opts)
     c.convert()
 
 cmdtable = {
     "convert":
         (_convert,
          [('A', 'authors', '', 'username mapping filename'),
           ('', 'datesort', None, 'try to sort changesets by date')],
          'hg convert [OPTION]... SOURCE [DEST [MAPFILE]]'),
 }