view mercurial/changelog.py @ 14252:19067884c5f5

revlog: calculate base revisions iteratively

This is in preparation for generaldelta, where the revlog entry base field is
reinterpreted as the deltaparent. For that reason we also rename the base
function to chainbase.

Without generaldelta, performance is unaffected, but generaldelta will suffer
from this in _addrevision, since delta chains will be walked repeatedly.
A cache has been added to eliminate this problem completely.

# 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

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):
    extra = {}
    for l in text.split('\0'):
        if l:
            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)

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, fp, buf):
        self.data = buf
        self.fp = fp
        self.offset = fp.tell()
        self.size = util.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")
        self._realopener = opener
        self._delayed = False
        self._divert = False

    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:
            nfile = self.opener(self.indexfile + ".a")
            n = nfile.name
            nfile.close()
            util.rename(n, n[:-2])
        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._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 metadatas, 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), [], "", {'branch': 'default'})
        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])

        extra_data = l[2].split(' ', 2)
        if len(extra_data) != 3:
            time = float(extra_data.pop(0))
            try:
                # various tools did silly things with the time zone field.
                timezone = int(extra_data[0])
            except ValueError:
                timezone = 0
            extra = {}
        else:
            time, timezone, extra = extra_data
            time, timezone = float(time), int(timezone)
            extra = decodeextra(extra)
        if not extra.get('branch'):
            extra['branch'] = 'default'
        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):
        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))

        # strip trailing whitespace and leading and trailing empty lines
        desc = '\n'.join([l.rstrip() for l in desc.splitlines()]).strip('\n')

        user, desc = encoding.fromlocal(user), encoding.fromlocal(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)