mercurial/changelog.py

context: generate filtered manifest efficiently for exact matchers

When the matcher is exact, there's no reason to iterate over the entire
manifest. It's much more efficient to iterate over the list of files instead.

For a repository with approximately 300,000 files, this speeds up
hg log -l10 --patch --follow for a frequently modified file from 16.5 seconds
to 10.5 seconds.

# 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):
    """
    >>> sorted(decodeextra(encodeextra({'foo': 'bar', 'baz': chr(0) + '2'})
    ...                    ).iteritems())
    [('baz', '\\x002'), ('branch', 'default'), ('foo', 'bar')]
    >>> sorted(decodeextra(encodeextra({'foo': 'bar',
    ...                                 'baz': chr(92) + chr(0) + '2'})
    ...                    ).iteritems())
    [('baz', '\\\\\\x002'), ('branch', 'default'), ('foo', 'bar')]
    """
    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)

def stripdesc(desc):
    """strip trailing whitespace and leading and trailing empty lines"""
    return '\n'.join([l.rstrip() for l in desc.splitlines()]).strip('\n')

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, vfs, name, mode, buf):
        self.data = buf
        fp = vfs(name, mode)
        self.fp = fp
        self.offset = fp.tell()
        self.size = vfs.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._delaybuf = []
        self._divert = False
        self.filteredrevs = frozenset()

    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__"""
        if len(self.filteredrevs) == 0:
            return revlog.revlog.__iter__(self)

        def filterediter():
            for i in xrange(len(self)):
                if i not in self.filteredrevs:
                    yield i

        return filterediter()

    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(hex(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:
            tmpname = self.indexfile + ".a"
            nfile = self.opener.open(tmpname)
            nfile.close()
            self.opener.rename(tmpname, self.indexfile)
        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))

        desc = stripdesc(desc)

        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)

    def branchinfo(self, rev):
        """return the branch name and open/close state of a revision

        This function exists because creating a changectx object
        just to access this is costly."""
        extra = self.read(rev)[5]
        return encoding.tolocal(extra.get("branch")), 'close' in extra