mercurial/manifest.py

manifest: rewrite find(node, f) in terms of read(node)

Since find() now always works with a full manifest, we can simplify by
calling read() to give us that manifest. That way, we also populate
the manifest cache. However, now that we no longer parse the manifest
text into a Python type (thanks, lazymanifest/Augie), the cost of
parsing (scanning for newlines, really) is small enough that it seems
generally drowned by revlog reading.

# 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
import array, struct


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 ((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:
            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)

        _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 keys(self):
        return [x[0] for x in self._lm]

    def iterkeys(self):
        return iter(self.keys())

    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.iterkeys())
        files.difference_update(m2.iterkeys())
        return files

    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)

        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 __iter__(self):
        return (x[0] for x in self._lm)

    def copy(self):
        c = manifestdict('')
        c._lm = self._lm.copy()
        return c

    def iteritems(self):
        return (x[:2] for x in self._lm)

    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

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