clfilter: introduce `filteredrevs` attribute on changelog

This changeset allows changelog object to be "filtered". You can assign a set of
revision numbers to the `changelog.filteredrevs` attributes. The changelog will
then pretends these revision does not exists in this repo.

A few methods need to be altered to achieve this behavior:

- tip
- __iter_
- irevs
- hasnode
- headrevs

For consistency and to help debugging, the following methods are altered too.
Tests tend to show it's not necessary to alter them but have them raise proper
exception helps to detect bad acces to filtered revisions.

- rev
- node
- linkrev
- parentrevs
- flags

The following methods would also need alteration for consistency purpose but
this is non-trivial and not done yet.

- nodemap
- strip

The C version of headrevs is not run if there is any revision to filter. It'll
need a proper rewrite later to restore performance.

mercurial/changelog.py

@@ -1,254 +1,330
 # changelog.py - changelog class for mercurial
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from node import bin, hex, nullid
 from i18n import _
 import util, error, revlog, encoding
 
 _defaultextra = {'branch': 'default'}
 
 def _string_escape(text):
     """
     >>> d = {'nl': chr(10), 'bs': chr(92), 'cr': chr(13), 'nul': chr(0)}
     >>> s = "ab%(nl)scd%(bs)s%(bs)sn%(nul)sab%(cr)scd%(bs)s%(nl)s" % d
     >>> s
     'ab\\ncd\\\\\\\\n\\x00ab\\rcd\\\\\\n'
     >>> res = _string_escape(s)
     >>> s == res.decode('string_escape')
     True
     """
     # subset of the string_escape codec
     text = text.replace('\\', '\\\\').replace('\n', '\\n').replace('\r', '\\r')
     return text.replace('\0', '\\0')
 
 def decodeextra(text):
     """
     >>> decodeextra(encodeextra({'foo': 'bar', 'baz': chr(0) + '2'}))
     {'foo': 'bar', 'baz': '\\x002', 'branch': 'default'}
     >>> decodeextra(encodeextra({'foo': 'bar', 'baz': chr(92) + chr(0) + '2'}))
     {'foo': 'bar', 'baz': '\\\\\\x002', 'branch': 'default'}
     """
     extra = _defaultextra.copy()
     for l in text.split('\0'):
         if l:
             if '\\0' in l:
                 # fix up \0 without getting into trouble with \\0
                 l = l.replace('\\\\', '\\\\\n')
                 l = l.replace('\\0', '\0')
                 l = l.replace('\n', '')
             k, v = l.decode('string_escape').split(':', 1)
             extra[k] = v
     return extra
 
 def encodeextra(d):
     # keys must be sorted to produce a deterministic changelog entry
     items = [_string_escape('%s:%s' % (k, d[k])) for k in sorted(d)]
     return "\0".join(items)
 
 class appender(object):
     '''the changelog index must be updated last on disk, so we use this class
     to delay writes to it'''
     def __init__(self, fp, buf):
         self.data = buf
         self.fp = fp
         self.offset = fp.tell()
         self.size = util.fstat(fp).st_size
 
     def end(self):
         return self.size + len("".join(self.data))
     def tell(self):
         return self.offset
     def flush(self):
         pass
     def close(self):
         self.fp.close()
 
     def seek(self, offset, whence=0):
         '''virtual file offset spans real file and data'''
         if whence == 0:
             self.offset = offset
         elif whence == 1:
             self.offset += offset
         elif whence == 2:
             self.offset = self.end() + offset
         if self.offset < self.size:
             self.fp.seek(self.offset)
 
     def read(self, count=-1):
         '''only trick here is reads that span real file and data'''
         ret = ""
         if self.offset < self.size:
             s = self.fp.read(count)
             ret = s
             self.offset += len(s)
             if count > 0:
                 count -= len(s)
         if count != 0:
             doff = self.offset - self.size
             self.data.insert(0, "".join(self.data))
             del self.data[1:]
             s = self.data[0][doff:doff + count]
             self.offset += len(s)
             ret += s
         return ret
 
     def write(self, s):
         self.data.append(str(s))
         self.offset += len(s)
 
 def delayopener(opener, target, divert, buf):
     def o(name, mode='r'):
         if name != target:
             return opener(name, mode)
         if divert:
             return opener(name + ".a", mode.replace('a', 'w'))
         # otherwise, divert to memory
         return appender(opener(name, mode), buf)
     return o
 
 class changelog(revlog.revlog):
     def __init__(self, opener):
         revlog.revlog.__init__(self, opener, "00changelog.i")
         if self._initempty:
             # changelogs don't benefit from generaldelta
             self.version &= ~revlog.REVLOGGENERALDELTA
             self._generaldelta = False
         self._realopener = opener
         self._delayed = False
         self._divert = False
+        self.filteredrevs = ()
+
+    def tip(self):
+        """filtered version of revlog.tip"""
+        for i in xrange(len(self) -1, -2, -1):
+            if i not in self.filteredrevs:
+                return self.node(i)
+
+    def __iter__(self):
+        """filtered version of revlog.__iter__"""
+        for i in xrange(len(self)):
+            if i not in self.filteredrevs:
+                yield i
+
+    def revs(self, start=0, stop=None):
+        """filtered version of revlog.revs"""
+        for i in super(changelog, self).revs(start, stop):
+            if i not in self.filteredrevs:
+                yield i
+
+    @util.propertycache
+    def nodemap(self):
+        # XXX need filtering too
+        self.rev(self.node(0))
+        return self._nodecache
+
+    def hasnode(self, node):
+        """filtered version of revlog.hasnode"""
+        try:
+            i = self.rev(node)
+            return i not in self.filteredrevs
+        except KeyError:
+            return False
+
+    def headrevs(self):
+        if self.filteredrevs:
+            # XXX we should fix and use the C version
+            return self._headrevs()
+        return super(changelog, self).headrevs()
+
+    def strip(self, *args, **kwargs):
+        # XXX make something better than assert
+        # We can't expect proper strip behavior if we are filtered.
+        assert not self.filteredrevs
+        super(changelog, self).strip(*args, **kwargs)
+
+    def rev(self, node):
+        """filtered version of revlog.rev"""
+        r = super(changelog, self).rev(node)
+        if r in self.filteredrevs:
+            raise error.LookupError(node, self.indexfile, _('no node'))
+        return r
+
+    def node(self, rev):
+        """filtered version of revlog.node"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).node(rev)
+
+    def linkrev(self, rev):
+        """filtered version of revlog.linkrev"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).linkrev(rev)
+
+    def parentrevs(self, rev):
+        """filtered version of revlog.parentrevs"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).parentrevs(rev)
+
+    def flags(self, rev):
+        """filtered version of revlog.flags"""
+        if rev in self.filteredrevs:
+            raise IndexError(rev)
+        return super(changelog, self).flags(rev)
 
     def delayupdate(self):
         "delay visibility of index updates to other readers"
         self._delayed = True
         self._divert = (len(self) == 0)
         self._delaybuf = []
         self.opener = delayopener(self._realopener, self.indexfile,
                                   self._divert, self._delaybuf)
 
     def finalize(self, tr):
         "finalize index updates"
         self._delayed = False
         self.opener = self._realopener
         # move redirected index data back into place
         if self._divert:
             nfile = self.opener(self.indexfile + ".a")
             n = nfile.name
             nfile.close()
             util.rename(n, n[:-2])
         elif self._delaybuf:
             fp = self.opener(self.indexfile, 'a')
             fp.write("".join(self._delaybuf))
             fp.close()
             self._delaybuf = []
         # split when we're done
         self.checkinlinesize(tr)
 
     def readpending(self, file):
         r = revlog.revlog(self.opener, file)
         self.index = r.index
         self.nodemap = r.nodemap
         self._nodecache = r._nodecache
         self._chunkcache = r._chunkcache
 
     def writepending(self):
         "create a file containing the unfinalized state for pretxnchangegroup"
         if self._delaybuf:
             # make a temporary copy of the index
             fp1 = self._realopener(self.indexfile)
             fp2 = self._realopener(self.indexfile + ".a", "w")
             fp2.write(fp1.read())
             # add pending data
             fp2.write("".join(self._delaybuf))
             fp2.close()
             # switch modes so finalize can simply rename
             self._delaybuf = []
             self._divert = True
 
         if self._divert:
             return True
 
         return False
 
     def checkinlinesize(self, tr, fp=None):
         if not self._delayed:
             revlog.revlog.checkinlinesize(self, tr, fp)
 
     def read(self, node):
         """
         format used:
         nodeid\n        : manifest node in ascii
         user\n          : user, no \n or \r allowed
         time tz extra\n : date (time is int or float, timezone is int)
                         : extra is metadata, encoded and separated by '\0'
                         : older versions ignore it
         files\n\n       : files modified by the cset, no \n or \r allowed
         (.*)            : comment (free text, ideally utf-8)
 
         changelog v0 doesn't use extra
         """
         text = self.revision(node)
         if not text:
             return (nullid, "", (0, 0), [], "", _defaultextra)
         last = text.index("\n\n")
         desc = encoding.tolocal(text[last + 2:])
         l = text[:last].split('\n')
         manifest = bin(l[0])
         user = encoding.tolocal(l[1])
 
         tdata = l[2].split(' ', 2)
         if len(tdata) != 3:
             time = float(tdata[0])
             try:
                 # various tools did silly things with the time zone field.
                 timezone = int(tdata[1])
             except ValueError:
                 timezone = 0
             extra = _defaultextra
         else:
             time, timezone = float(tdata[0]), int(tdata[1])
             extra = decodeextra(tdata[2])
 
         files = l[3:]
         return (manifest, user, (time, timezone), files, desc, extra)
 
     def add(self, manifest, files, desc, transaction, p1, p2,
                   user, date=None, extra=None):
         # Convert to UTF-8 encoded bytestrings as the very first
         # thing: calling any method on a localstr object will turn it
         # into a str object and the cached UTF-8 string is thus lost.
         user, desc = encoding.fromlocal(user), encoding.fromlocal(desc)
 
         user = user.strip()
         # An empty username or a username with a "\n" will make the
         # revision text contain two "\n\n" sequences -> corrupt
         # repository since read cannot unpack the revision.
         if not user:
             raise error.RevlogError(_("empty username"))
         if "\n" in user:
             raise error.RevlogError(_("username %s contains a newline")
                                     % repr(user))
 
         # strip trailing whitespace and leading and trailing empty lines
         desc = '\n'.join([l.rstrip() for l in desc.splitlines()]).strip('\n')
 
         if date:
             parseddate = "%d %d" % util.parsedate(date)
         else:
             parseddate = "%d %d" % util.makedate()
         if extra:
             branch = extra.get("branch")
             if branch in ("default", ""):
                 del extra["branch"]
             elif branch in (".", "null", "tip"):
                 raise error.RevlogError(_('the name \'%s\' is reserved')
                                         % branch)
         if extra:
             extra = encodeextra(extra)
             parseddate = "%s %s" % (parseddate, extra)
         l = [hex(manifest), user, parseddate] + sorted(files) + ["", desc]
         text = "\n".join(l)
         return self.addrevision(text, transaction, len(self), p1, p2)