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
# manifest.py - manifest revision class for mercurial
#
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# 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