treemanifest: create treemanifest class

There are a number of problems with large and flat manifests. Copying
from http://mercurial.selenic.com/wiki/ManifestShardingPlan:

 * manifest too large for RAM

 * manifest resolution too much CPU (long delta chains)

 * committing is slow because entire manifest has to be hashed

 * impossible for narrow clone to leave out part of manifest as all is
   needed to calculate new hash

 * diffing two revisions involves traversing entire subdirectories
   even if identical

This is a first step in a series introducing a manifest revlog per
directory.

This change adds a new manifest class: treemanifest, which is a tree
where each node has a dict of files (nodeids), a dict of flags, and a
dict of subdirectories (treemanifests). So far, it behaves just like
manifestdict, but it will later help us write one manifest revlog per
directory. The new class is still unused; it will be used after the
next change.

The code is not yet optimized. Running with it (see below) makes most
or all operations slower. Once we start storing manifest revlogs for
every directory, it should be possible to make many of these
operations much faster. The fastdelta() optimization has been
intentionally not implemented for the treemanifests. We can implement
it later if necessary.

All tests pass when run with the following patch (and without, of
couse):

  --- a/mercurial/manifest.py     Thu Mar 19 11:08:42 2015 -0700
  +++ b/mercurial/manifest.py     Thu Mar 19 11:15:50 2015 -0700
  @@ -596,7 +596,7 @@ class manifest(revlog.revlog):
               return None, None

       def add(self, m, transaction, link, p1, p2, added, removed):
  -        if p1 in self._mancache:
  +        if False and p1 in self._mancache:
               # If our first parent is in the manifest cache, we can
               # compute a delta here using properties we know about the
               # manifest up-front, which may save time later for the
  @@ -626,3 +626,5 @@ class manifest(revlog.revlog):
           self._mancache[n] = (m, arraytext)

           return n
  +
  +manifestdict = treemanifest

mercurial/manifest.py

@@ -1,406 +1,628 b''
 # manifest.py - manifest revision 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 i18n import _
 import mdiff, parsers, error, revlog, util, scmutil
 import array, struct
 
 propertycache = util.propertycache
 
 class _lazymanifest(dict):
     """This is the pure implementation of lazymanifest.
 
     It has not been optimized *at all* and is not lazy.
     """
 
     def __init__(self, data):
         # This init method does a little bit of excessive-looking
         # precondition checking. This is so that the behavior of this
         # class exactly matches its C counterpart to try and help
         # prevent surprise breakage for anyone that develops against
         # the pure version.
         if data and data[-1] != '\n':
             raise ValueError('Manifest did not end in a newline.')
         dict.__init__(self)
         prev = None
         for l in data.splitlines():
             if prev is not None and prev > l:
                 raise ValueError('Manifest lines not in sorted order.')
             prev = l
             f, n = l.split('\0')
             if len(n) > 40:
                 self[f] = revlog.bin(n[:40]), n[40:]
             else:
                 self[f] = revlog.bin(n), ''
 
     def __setitem__(self, k, v):
         node, flag = v
         assert node is not None
         if len(node) > 21:
             node = node[:21] # match c implementation behavior
         dict.__setitem__(self, k, (node, flag))
 
     def __iter__(self):
         return iter(sorted(dict.keys(self)))
 
     def iterkeys(self):
         return iter(sorted(dict.keys(self)))
 
     def iterentries(self):
         return ((f, e[0], e[1]) for f, e in sorted(self.iteritems()))
 
     def copy(self):
         c = _lazymanifest('')
         c.update(self)
         return c
 
     def diff(self, m2, clean=False):
         '''Finds changes between the current manifest and m2.'''
         diff = {}
 
         for fn, e1 in self.iteritems():
             if fn not in m2:
                 diff[fn] = e1, (None, '')
             else:
                 e2 = m2[fn]
                 if e1 != e2:
                     diff[fn] = e1, e2
                 elif clean:
                     diff[fn] = None
 
         for fn, e2 in m2.iteritems():
             if fn not in self:
                 diff[fn] = (None, ''), e2
 
         return diff
 
     def filtercopy(self, filterfn):
         c = _lazymanifest('')
         for f, n, fl in self.iterentries():
             if filterfn(f):
                 c[f] = n, fl
         return c
 
     def text(self):
         """Get the full data of this manifest as a bytestring."""
         fl = sorted(self.iterentries())
 
         _hex = revlog.hex
         # if this is changed to support newlines in filenames,
         # be sure to check the templates/ dir again (especially *-raw.tmpl)
         return ''.join("%s\0%s%s\n" % (
             f, _hex(n[:20]), flag) for f, n, flag in fl)
 
 try:
     _lazymanifest = parsers.lazymanifest
 except AttributeError:
     pass
 
 class manifestdict(object):
     def __init__(self, data=''):
         self._lm = _lazymanifest(data)
 
     def __getitem__(self, key):
         return self._lm[key][0]
 
     def find(self, key):
         return self._lm[key]
 
     def __len__(self):
         return len(self._lm)
 
     def __setitem__(self, key, node):
         self._lm[key] = node, self.flags(key, '')
 
     def __contains__(self, key):
         return key in self._lm
 
     def __delitem__(self, key):
         del self._lm[key]
 
     def __iter__(self):
         return self._lm.__iter__()
 
     def iterkeys(self):
         return self._lm.iterkeys()
 
     def keys(self):
         return list(self.iterkeys())
 
     def intersectfiles(self, files):
         '''make a new lazymanifest with the intersection of self with files
 
         The algorithm assumes that files is much smaller than self.'''
         ret = manifestdict()
         lm = self._lm
         for fn in files:
             if fn in lm:
                 ret._lm[fn] = self._lm[fn]
         return ret
 
     def filesnotin(self, m2):
         '''Set of files in this manifest that are not in the other'''
         files = set(self)
         files.difference_update(m2)
         return files
 
     @propertycache
     def _dirs(self):
         return scmutil.dirs(self)
 
     def dirs(self):
         return self._dirs
 
     def hasdir(self, dir):
         return dir in self._dirs
 
     def matches(self, match):
         '''generate a new manifest filtered by the match argument'''
         if match.always():
             return self.copy()
 
         files = match.files()
         if (len(files) < 100 and (match.matchfn == match.exact or
             (not match.anypats() and util.all(fn in self for fn in files)))):
             return self.intersectfiles(files)
 
         lm = manifestdict('')
         lm._lm = self._lm.filtercopy(match)
         return lm
 
     def diff(self, m2, clean=False):
         '''Finds changes between the current manifest and m2.
 
         Args:
           m2: the manifest to which this manifest should be compared.
           clean: if true, include files unchanged between these manifests
                  with a None value in the returned dictionary.
 
         The result is returned as a dict with filename as key and
         values of the form ((n1,fl1),(n2,fl2)), where n1/n2 is the
         nodeid in the current/other manifest and fl1/fl2 is the flag
         in the current/other manifest. Where the file does not exist,
         the nodeid will be None and the flags will be the empty
         string.
         '''
         return self._lm.diff(m2._lm, clean)
 
     def setflag(self, key, flag):
         self._lm[key] = self[key], flag
 
     def get(self, key, default=None):
         try:
             return self._lm[key][0]
         except KeyError:
             return default
 
     def flags(self, key, default=''):
         try:
             return self._lm[key][1]
         except KeyError:
             return default
 
     def copy(self):
         c = manifestdict('')
         c._lm = self._lm.copy()
         return c
 
     def iteritems(self):
         return (x[:2] for x in self._lm.iterentries())
 
     def text(self):
         return self._lm.text()
 
     def fastdelta(self, base, changes):
         """Given a base manifest text as an array.array and a list of changes
         relative to that text, compute a delta that can be used by revlog.
         """
         delta = []
         dstart = None
         dend = None
         dline = [""]
         start = 0
         # zero copy representation of base as a buffer
         addbuf = util.buffer(base)
 
         # start with a readonly loop that finds the offset of
         # each line and creates the deltas
         for f, todelete in changes:
             # bs will either be the index of the item or the insert point
             start, end = _msearch(addbuf, f, start)
             if not todelete:
                 h, fl = self._lm[f]
                 l = "%s\0%s%s\n" % (f, revlog.hex(h), fl)
             else:
                 if start == end:
                     # item we want to delete was not found, error out
                     raise AssertionError(
                             _("failed to remove %s from manifest") % f)
                 l = ""
             if dstart is not None and dstart <= start and dend >= start:
                 if dend < end:
                     dend = end
                 if l:
                     dline.append(l)
             else:
                 if dstart is not None:
                     delta.append([dstart, dend, "".join(dline)])
                 dstart = start
                 dend = end
                 dline = [l]
 
         if dstart is not None:
             delta.append([dstart, dend, "".join(dline)])
         # apply the delta to the base, and get a delta for addrevision
         deltatext, arraytext = _addlistdelta(base, delta)
         return arraytext, deltatext
 
 def _msearch(m, s, lo=0, hi=None):
     '''return a tuple (start, end) that says where to find s within m.
 
     If the string is found m[start:end] are the line containing
     that string.  If start == end the string was not found and
     they indicate the proper sorted insertion point.
 
     m should be a buffer or a string
     s is a string'''
     def advance(i, c):
         while i < lenm and m[i] != c:
             i += 1
         return i
     if not s:
         return (lo, lo)
     lenm = len(m)
     if not hi:
         hi = lenm
     while lo < hi:
         mid = (lo + hi) // 2
         start = mid
         while start > 0 and m[start - 1] != '\n':
             start -= 1
         end = advance(start, '\0')
         if m[start:end] < s:
             # we know that after the null there are 40 bytes of sha1
             # this translates to the bisect lo = mid + 1
             lo = advance(end + 40, '\n') + 1
         else:
             # this translates to the bisect hi = mid
             hi = start
     end = advance(lo, '\0')
     found = m[lo:end]
     if s == found:
         # we know that after the null there are 40 bytes of sha1
         end = advance(end + 40, '\n')
         return (lo, end + 1)
     else:
         return (lo, lo)
 
 def _checkforbidden(l):
     """Check filenames for illegal characters."""
     for f in l:
         if '\n' in f or '\r' in f:
             raise error.RevlogError(
                 _("'\\n' and '\\r' disallowed in filenames: %r") % f)
 
 
 # apply the changes collected during the bisect loop to our addlist
 # return a delta suitable for addrevision
 def _addlistdelta(addlist, x):
     # for large addlist arrays, building a new array is cheaper
     # than repeatedly modifying the existing one
     currentposition = 0
     newaddlist = array.array('c')
 
     for start, end, content in x:
         newaddlist += addlist[currentposition:start]
         if content:
             newaddlist += array.array('c', content)
 
         currentposition = end
 
     newaddlist += addlist[currentposition:]
 
     deltatext = "".join(struct.pack(">lll", start, end, len(content))
                    + content for start, end, content in x)
     return deltatext, newaddlist
 
+def _splittopdir(f):
+    if '/' in f:
+        dir, subpath = f.split('/', 1)
+        return dir + '/', subpath
+    else:
+        return '', f
+
+class treemanifest(object):
+    def __init__(self, text=''):
+        self._dirs = {}
+        # Using _lazymanifest here is a little slower than plain old dicts
+        self._files = {}
+        self._flags = {}
+        lm = _lazymanifest(text)
+        for f, n, fl in lm.iterentries():
+            self[f] = n
+            if fl:
+                self.setflag(f, fl)
+
+    def __len__(self):
+        size = len(self._files)
+        for m in self._dirs.values():
+            size += m.__len__()
+        return size
+
+    def iteritems(self):
+        for p, n in sorted(self._dirs.items() + self._files.items()):
+            if p in self._files:
+                yield p, n
+            else:
+                for sf, sn in n.iteritems():
+                    yield p + sf, sn
+
+    def iterkeys(self):
+        for p in sorted(self._dirs.keys() + self._files.keys()):
+            if p in self._files:
+                yield p
+            else:
+                for f in self._dirs[p].iterkeys():
+                    yield p + f
+
+    def keys(self):
+        return list(self.iterkeys())
+
+    def __iter__(self):
+        return self.iterkeys()
+
+    def __contains__(self, f):
+        if f is None:
+            return False
+        dir, subpath = _splittopdir(f)
+        if dir:
+            if dir not in self._dirs:
+                return False
+            return self._dirs[dir].__contains__(subpath)
+        else:
+            return f in self._files
+
+    def get(self, f, default=None):
+        dir, subpath = _splittopdir(f)
+        if dir:
+            if dir not in self._dirs:
+                return default
+            return self._dirs[dir].get(subpath, default)
+        else:
+            return self._files.get(f, default)
+
+    def __getitem__(self, f):
+        dir, subpath = _splittopdir(f)
+        if dir:
+            return self._dirs[dir].__getitem__(subpath)
+        else:
+            return self._files[f]
+
+    def flags(self, f):
+        dir, subpath = _splittopdir(f)
+        if dir:
+            if dir not in self._dirs:
+                return ''
+            return self._dirs[dir].flags(subpath)
+        else:
+            if f in self._dirs:
+                return ''
+            return self._flags.get(f, '')
+
+    def find(self, f):
+        dir, subpath = _splittopdir(f)
+        if dir:
+            return self._dirs[dir].find(subpath)
+        else:
+            return self._files[f], self._flags.get(f, '')
+
+    def __delitem__(self, f):
+        dir, subpath = _splittopdir(f)
+        if dir:
+            self._dirs[dir].__delitem__(subpath)
+            # If the directory is now empty, remove it
+            if not self._dirs[dir]._dirs and not self._dirs[dir]._files:
+                del self._dirs[dir]
+        else:
+            del self._files[f]
+            if f in self._flags:
+                del self._flags[f]
+
+    def __setitem__(self, f, n):
+        assert n is not None
+        dir, subpath = _splittopdir(f)
+        if dir:
+            if dir not in self._dirs:
+                self._dirs[dir] = treemanifest()
+            self._dirs[dir].__setitem__(subpath, n)
+        else:
+            self._files[f] = n
+
+    def setflag(self, f, flags):
+        """Set the flags (symlink, executable) for path f."""
+        dir, subpath = _splittopdir(f)
+        if dir:
+            if dir not in self._dirs:
+                self._dirs[dir] = treemanifest()
+            self._dirs[dir].setflag(subpath, flags)
+        else:
+            self._flags[f] = flags
+
+    def copy(self):
+        copy = treemanifest()
+        for d in self._dirs:
+            copy._dirs[d] = self._dirs[d].copy()
+        copy._files = dict.copy(self._files)
+        copy._flags = dict.copy(self._flags)
+        return copy
+
+    def intersectfiles(self, files):
+        '''make a new treemanifest with the intersection of self with files
+
+        The algorithm assumes that files is much smaller than self.'''
+        ret = treemanifest()
+        for fn in files:
+            if fn in self:
+                ret[fn] = self[fn]
+                flags = self.flags(fn)
+                if flags:
+                    ret.setflag(fn, flags)
+        return ret
+
+    def filesnotin(self, m2):
+        '''Set of files in this manifest that are not in the other'''
+        files = set(self.iterkeys())
+        files.difference_update(m2.iterkeys())
+        return files
+
+    @propertycache
+    def _alldirs(self):
+        return scmutil.dirs(self)
+
+    def dirs(self):
+        return self._alldirs
+
+    def hasdir(self, dir):
+        return dir in self._alldirs
+
+    def matches(self, match):
+        '''generate a new manifest filtered by the match argument'''
+        if match.always():
+            return self.copy()
+
+        files = match.files()
+        if (match.matchfn == match.exact or
+            (not match.anypats() and util.all(fn in self for fn in files))):
+            return self.intersectfiles(files)
+
+        m = self.copy()
+        for fn in m.keys():
+            if not match(fn):
+                del m[fn]
+        return m
+
+    def diff(self, m2, clean=False):
+        '''Finds changes between the current manifest and m2.
+
+        Args:
+          m2: the manifest to which this manifest should be compared.
+          clean: if true, include files unchanged between these manifests
+                 with a None value in the returned dictionary.
+
+        The result is returned as a dict with filename as key and
+        values of the form ((n1,fl1),(n2,fl2)), where n1/n2 is the
+        nodeid in the current/other manifest and fl1/fl2 is the flag
+        in the current/other manifest. Where the file does not exist,
+        the nodeid will be None and the flags will be the empty
+        string.
+        '''
+        diff = {}
+
+        for fn, n1 in self.iteritems():
+            fl1 = self.flags(fn)
+            n2 = m2.get(fn, None)
+            fl2 = m2.flags(fn)
+            if n2 is None:
+                fl2 = ''
+            if n1 != n2 or fl1 != fl2:
+                diff[fn] = ((n1, fl1), (n2, fl2))
+            elif clean:
+                diff[fn] = None
+
+        for fn, n2 in m2.iteritems():
+            if fn not in self:
+                fl2 = m2.flags(fn)
+                diff[fn] = ((None, ''), (n2, fl2))
+
+        return diff
+
+    def text(self):
+        """Get the full data of this manifest as a bytestring."""
+        fl = self.keys()
+        _checkforbidden(fl)
+
+        hex, flags = revlog.hex, self.flags
+        # if this is changed to support newlines in filenames,
+        # be sure to check the templates/ dir again (especially *-raw.tmpl)
+        return ''.join("%s\0%s%s\n" % (f, hex(self[f]), flags(f)) for f in fl)
+
 class manifest(revlog.revlog):
     def __init__(self, opener):
         # During normal operations, we expect to deal with not more than four
         # revs at a time (such as during commit --amend). When rebasing large
         # stacks of commits, the number can go up, hence the config knob below.
         cachesize = 4
         opts = getattr(opener, 'options', None)
         if opts is not None:
             cachesize = opts.get('manifestcachesize', cachesize)
         self._mancache = util.lrucachedict(cachesize)
         revlog.revlog.__init__(self, opener, "00manifest.i")
 
     def readdelta(self, node):
         r = self.rev(node)
         d = mdiff.patchtext(self.revdiff(self.deltaparent(r), r))
         return manifestdict(d)
 
     def readfast(self, node):
         '''use the faster of readdelta or read'''
         r = self.rev(node)
         deltaparent = self.deltaparent(r)
         if deltaparent != revlog.nullrev and deltaparent in self.parentrevs(r):
             return self.readdelta(node)
         return self.read(node)
 
     def read(self, node):
         if node == revlog.nullid:
             return manifestdict() # don't upset local cache
         if node in self._mancache:
             return self._mancache[node][0]
         text = self.revision(node)
         arraytext = array.array('c', text)
         m = manifestdict(text)
         self._mancache[node] = (m, arraytext)
         return m
 
     def find(self, node, f):
         '''look up entry for a single file efficiently.
         return (node, flags) pair if found, (None, None) if not.'''
         m = self.read(node)
         try:
             return m.find(f)
         except KeyError:
             return None, None
 
     def add(self, m, transaction, link, p1, p2, added, removed):
         if p1 in self._mancache:
             # If our first parent is in the manifest cache, we can
             # compute a delta here using properties we know about the
             # manifest up-front, which may save time later for the
             # revlog layer.
 
             _checkforbidden(added)
             # combine the changed lists into one list for sorting
             work = [(x, False) for x in added]
             work.extend((x, True) for x in removed)
             # this could use heapq.merge() (from Python 2.6+) or equivalent
             # since the lists are already sorted
             work.sort()
 
             arraytext, deltatext = m.fastdelta(self._mancache[p1][1], work)
             cachedelta = self.rev(p1), deltatext
             text = util.buffer(arraytext)
         else:
             # The first parent manifest isn't already loaded, so we'll
             # just encode a fulltext of the manifest and pass that
             # through to the revlog layer, and let it handle the delta
             # process.
             text = m.text()
             arraytext = array.array('c', text)
             cachedelta = None
 
         n = self.addrevision(text, transaction, link, p1, p2, cachedelta)
         self._mancache[n] = (m, arraytext)
 
         return n