manifest: document the extra letter in working copy manifest node
As the second developer to get confused by this in November, I'm adding some
documentation for the next poor soul.
# 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
import array, struct
class manifestdict(dict):
def __init__(self, mapping=None, flags=None):
if mapping is None:
mapping = {}
if flags is None:
flags = {}
dict.__init__(self, mapping)
self._flags = flags
def flags(self, f):
return self._flags.get(f, "")
def withflags(self):
return set(self._flags.keys())
def setflag(self, f, flags):
"""Set the flags (symlink, executable) for path f."""
self._flags[f] = flags
def copy(self):
return manifestdict(self, dict.copy(self._flags))
def intersectfiles(self, files):
'''make a new manifestdict with the intersection of self with files
The algorithm assumes that files is much smaller than self.'''
ret = manifestdict()
for fn in files:
if fn in self:
ret[fn] = self[fn]
flags = self._flags.get(fn, None)
if flags:
ret._flags[fn] = flags
return ret
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)
mf = self.copy()
for fn in mf.keys():
if not match(fn):
del mf[fn]
return mf
def diff(self, m2):
'''Finds changes between the current manifest and m2. 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.get(fn, '')
n2 = m2.get(fn, None)
fl2 = m2._flags.get(fn, '')
if n2 is None:
fl2 = ''
if n1 != n2 or fl1 != fl2:
diff[fn] = ((n1, fl1), (n2, fl2))
for fn, n2 in m2.iteritems():
if fn not in self:
fl2 = m2._flags.get(fn, '')
diff[fn] = ((None, ''), (n2, fl2))
return diff
def text(self):
"""Get the full data of this manifest as a bytestring."""
fl = sorted(self)
_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)
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:
l = "%s\0%s%s\n" % (f, revlog.hex(self[f]), self.flags(f))
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 _parse(lines):
mfdict = manifestdict()
parsers.parse_manifest(mfdict, mfdict._flags, lines)
return mfdict
class manifest(revlog.revlog):
def __init__(self, opener):
# we expect to deal with not more than four revs at a time,
# during a commit --amend
self._mancache = util.lrucachedict(4)
revlog.revlog.__init__(self, opener, "00manifest.i")
def readdelta(self, node):
r = self.rev(node)
return _parse(mdiff.patchtext(self.revdiff(self.deltaparent(r), r)))
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)
mapping = _parse(text)
self._mancache[node] = (mapping, arraytext)
return mapping
def find(self, node, f):
'''look up entry for a single file efficiently.
return (node, flags) pair if found, (None, None) if not.'''
if node in self._mancache:
mapping = self._mancache[node][0]
return mapping.get(f), mapping.flags(f)
text = self.revision(node)
start, end = _msearch(text, f)
if start == end:
return None, None
l = text[start:end]
f, n = l.split('\0')
return revlog.bin(n[:40]), n[40:-1]
def add(self, map, 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 = map.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 = map.text()
arraytext = array.array('c', text)
cachedelta = None
n = self.addrevision(text, transaction, link, p1, p2, cachedelta)
self._mancache[n] = (map, arraytext)
return n