comparison mercurial/tags.py @ 43076:2372284d9457

formatting: blacken the codebase

This is using my patch to black
(https://github.com/psf/black/pull/826) so we don't un-wrap collection
literals.

Done with:

  hg files 'set:**.py - mercurial/thirdparty/** - "contrib/python-zstandard/**"' | xargs black -S

# skip-blame mass-reformatting only

# no-check-commit reformats foo_bar functions

Differential Revision: https://phab.mercurial-scm.org/D6971

43075:57875cf423c9

    error,
    match as matchmod,
    scmutil,
    util,
)
from .utils import (
    stringutil,
)

# Tags computation can be expensive and caches exist to make it fast in
# the common case.
#
# The "hgtagsfnodes1" cache file caches the .hgtags filenode values for

# Tags are written sorted by tag name.
#
# Tags associated with multiple changesets have an entry for each changeset.
# The most recent changeset (in terms of revlog ordering for the head
# setting it) for each tag is last.

def fnoderevs(ui, repo, revs):
    """return the list of '.hgtags' fnodes used in a set revisions

    This is returned as list of unique fnodes. We use a list instead of a set

    nodes = [tonode(r) for r in revs]
    fnodes = _getfnodes(ui, repo, nodes)
    fnodes = _filterfnodes(fnodes, nodes)
    return fnodes

def _nulltonone(value):
    """convert nullid to None

    For tag value, nullid means "deleted". This small utility function helps
    translating that to None."""
    if value == nullid:
        return None
    return value

def difftags(ui, repo, oldfnodes, newfnodes):
    """list differences between tags expressed in two set of file-nodes

    The list contains entries in the form: (tagname, oldvalue, new value).

        old = _nulltonone(old)
        if old is not None:
            entries.append((tag, old, None))
    entries.sort()
    return entries

def writediff(fp, difflist):
    """write tags diff information to a file.

    Data are stored with a line based format:

            fp.write(remove % (old, tag))
        else:
            fp.write(updateold % (old, tag))
            fp.write(updatenew % (new, tag))

def findglobaltags(ui, repo):
    '''Find global tags in a repo: return a tagsmap

    tagsmap: tag name to (node, hist) 2-tuples.

        alltags = {}
        _updatetags(cachetags, alltags)
        return alltags

    for head in reversed(heads):  # oldest to newest
        assert head in repo.changelog.nodemap, (
               "tag cache returned bogus head %s" % short(head))
    fnodes = _filterfnodes(tagfnode, reversed(heads))
    alltags = _tagsfromfnodes(ui, repo, fnodes)

    # and update the cache (if necessary)
    if shouldwrite:
        _writetagcache(ui, repo, valid, alltags)
    return alltags

def _filterfnodes(tagfnode, nodes):
    """return a list of unique fnodes

    The order of this list matches the order of "nodes". Preserving this order

        if fnode and fnode not in seen:
            seen.add(fnode)
            fnodes.append(fnode)
    return fnodes

def _tagsfromfnodes(ui, repo, fnodes):
    """return a tagsmap from a list of file-node

    tagsmap: tag name to (node, hist) 2-tuples.

            fctx = fctx.filectx(fnode)
        filetags = _readtags(ui, repo, fctx.data().splitlines(), fctx)
        _updatetags(filetags, alltags)
    return alltags

def readlocaltags(ui, repo, alltags, tagtypes):
    '''Read local tags in repo. Update alltags and tagtypes.'''
    try:
        data = repo.vfs.read("localtags")
    except IOError as inst:

        return

    # localtags is in the local encoding; re-encode to UTF-8 on
    # input for consistency with the rest of this module.
    filetags = _readtags(
        ui, repo, data.splitlines(), "localtags",
        recode=encoding.fromlocal)

    # remove tags pointing to invalid nodes
    cl = repo.changelog
    for t in list(filetags):
        try:
            cl.rev(filetags[t][0])
        except (LookupError, ValueError):
            del filetags[t]

    _updatetags(filetags, alltags, 'local', tagtypes)

def _readtaghist(ui, repo, lines, fn, recode=None, calcnodelines=False):
    '''Read tag definitions from a file (or any source of lines).

    This function returns two sortdicts with similar information:

        if name not in bintaghist:
            bintaghist[name] = []
        bintaghist[name].append(nodebin)
    return bintaghist, hextaglines

def _readtags(ui, repo, lines, fn, recode=None, calcnodelines=False):
    '''Read tag definitions from a file (or any source of lines).

    Returns a mapping from tag name to (node, hist).

    "node" is the node id from the last line read for that name. "hist"
    is the list of node ids previously associated with it (in file order).
    All node ids are binary, not hex.
    '''
    filetags, nodelines = _readtaghist(ui, repo, lines, fn, recode=recode,
                                       calcnodelines=calcnodelines)
    # util.sortdict().__setitem__ is much slower at replacing then inserting
    # new entries. The difference can matter if there are thousands of tags.
    # Create a new sortdict to avoid the performance penalty.
    newtags = util.sortdict()
    for tag, taghist in filetags.items():
        newtags[tag] = (taghist[-1], taghist[:-1])
    return newtags

def _updatetags(filetags, alltags, tagtype=None, tagtypes=None):
    """Incorporate the tag info read from one file into dictionnaries

    The first one, 'alltags', is a "tagmaps" (see 'findglobaltags' for details).

        #  it supersedes us OR
        #  mutual supersedes and it has a higher rank
        # otherwise we win because we're tip-most
        anode, ahist = nodehist
        bnode, bhist = alltags[name]
        if (bnode != anode and anode in bhist and
            (bnode not in ahist or len(bhist) > len(ahist))):
            anode = bnode
        elif tagtype is not None:
            tagtypes[name] = tagtype
        ahist.extend([n for n in bhist if n not in ahist])
        alltags[name] = anode, ahist

def _filename(repo):
    """name of a tagcache file for a given repo or repoview"""
    filename = 'tags2'
    if repo.filtername:
        filename = '%s-%s' % (filename, repo.filtername)
    return filename

def _readtagcache(ui, repo):
    '''Read the tag cache.

    Returns a tuple (heads, fnodes, validinfo, cachetags, shouldwrite).

    # Case 1 (common): tip is the same, so nothing has changed.
    # (Unchanged tip trivially means no changesets have been added.
    # But, thanks to localrepository.destroyed(), it also means none
    # have been destroyed by strip or rollback.)
    if (cacherev == tiprev
            and cachenode == tipnode
            and cachehash == scmutil.filteredhash(repo, tiprev)):
        tags = _readtags(ui, repo, cachelines, cachefile.name)
        cachefile.close()
        return (None, None, None, tags, False)
    if cachefile:
        cachefile.close()               # ignore rest of file

    valid = (tiprev, tipnode, scmutil.filteredhash(repo, tiprev))

    repoheads = repo.heads()
    # Case 2 (uncommon): empty repo; get out quickly and don't bother

    if not len(repo.file('.hgtags')):
        # No tags have ever been committed, so we can avoid a
        # potentially expensive search.
        return ([], {}, valid, None, True)


    # Now we have to lookup the .hgtags filenode for every new head.
    # This is the most expensive part of finding tags, so performance
    # depends primarily on the size of newheads.  Worst case: no cache
    # file, so newheads == repoheads.
    # Reversed order helps the cache ('repoheads' is in descending order)
    cachefnode = _getfnodes(ui, repo, reversed(repoheads))

    # Caller has to iterate over all heads, but can use the filenodes in
    # cachefnode to get to each .hgtags revision quickly.
    return (repoheads, cachefnode, valid, None, True)

def _getfnodes(ui, repo, nodes):
    """return .hgtags fnodes for a list of changeset nodes

    Return value is a {node: fnode} mapping. There will be no entry for nodes

            cachefnode[node] = fnode

    fnodescache.write()

    duration = util.timer() - starttime
    ui.log('tagscache',
           '%d/%d cache hits/lookups in %0.4f seconds\n',
           fnodescache.hitcount, fnodescache.lookupcount, duration)
    return cachefnode

def _writetagcache(ui, repo, valid, cachetags):
    filename = _filename(repo)
    try:
        cachefile = repo.cachevfs(filename, 'w', atomictemp=True)
    except (OSError, IOError):
        return

    ui.log('tagscache', 'writing .hg/cache/%s with %d tags\n',
           filename, len(cachetags))

    if valid[2]:
        cachefile.write('%d %s %s\n' % (valid[0], hex(valid[1]), hex(valid[2])))
    else:
        cachefile.write('%d %s\n' % (valid[0], hex(valid[1])))

    try:
        cachefile.close()
    except (OSError, IOError):
        pass

def tag(repo, names, node, message, local, user, date, editor=False):
    '''tag a revision with one or more symbolic names.

    names is a list of strings or, when adding a single tag, names may be a
    string.

    date: date tuple to use if committing'''

    if not local:
        m = matchmod.exact(['.hgtags'])
        if any(repo.status(match=m, unknown=True, ignored=True)):
            raise error.Abort(_('working copy of .hgtags is changed'),
                             hint=_('please commit .hgtags manually'))

    with repo.wlock():
        repo.tags() # instantiate the cache
        _tag(repo, names, node, message, local, user, date,
             editor=editor)

def _tag(repo, names, node, message, local, user, date, extra=None,
         editor=False):
    if isinstance(names, bytes):
        names = (names,)

    branches = repo.branchmap()
    for name in names:
        repo.hook('pretag', throw=True, node=hex(node), tag=name,
                  local=local)
        if name in branches:
            repo.ui.warn(_("warning: tag %s conflicts with existing"
            " branch name\n") % name)

    def writetags(fp, names, munge, prevtags):
        fp.seek(0, io.SEEK_END)
        if prevtags and not prevtags.endswith('\n'):
            fp.write('\n')

            if munge:
                m = munge(name)
            else:
                m = name

            if (repo._tagscache.tagtypes and
                name in repo._tagscache.tagtypes):
                old = repo.tags().get(name, nullid)
                fp.write('%s %s\n' % (hex(old), m))
            fp.write('%s %s\n' % (hex(node), m))
        fp.close()

    if '.hgtags' not in repo.dirstate:
        repo[None].add(['.hgtags'])

    m = matchmod.exact(['.hgtags'])
    tagnode = repo.commit(message, user, date, extra=extra, match=m,
                          editor=editor)

    for name in names:
        repo.hook('tag', node=hex(node), tag=name, local=local)

    return tagnode

_fnodescachefile = 'hgtagsfnodes1'
_fnodesrecsize = 4 + 20 # changeset fragment + filenode
_fnodesmissingrec = '\xff' * 24

class hgtagsfnodescache(object):
    """Persistent cache mapping revisions to .hgtags filenodes.

    The cache is an array of records. Each item in the array corresponds to

    only parsed on read.

    Instances behave like lists. ``c[i]`` works where i is a rev or
    changeset node. Missing indexes are populated automatically on access.
    """
    def __init__(self, repo):
        assert repo.filtername is None

        self._repo = repo

        # Only for reporting purposes.
        self.lookupcount = 0
        self.hitcount = 0


        try:
            data = repo.cachevfs.read(_fnodescachefile)
        except (OSError, IOError):
            data = ""

        rev = ctx.rev()

        self.lookupcount += 1

        offset = rev * _fnodesrecsize
        record = '%s' % self._raw[offset:offset + _fnodesrecsize]
        properprefix = node[0:4]

        # Validate and return existing entry.
        if record != _fnodesmissingrec:
            fileprefix = record[0:4]

        self._writeentry(ctx.rev() * _fnodesrecsize, node[0:4], fnode)

    def _writeentry(self, offset, prefix, fnode):
        # Slices on array instances only accept other array.
        entry = bytearray(prefix + fnode)
        self._raw[offset:offset + _fnodesrecsize] = entry
        # self._dirtyoffset could be None.
        self._dirtyoffset = min(self._dirtyoffset or 0, offset or 0)

    def write(self):
        """Perform all necessary writes to cache file.

        not be obtained.
        """
        if self._dirtyoffset is None:
            return

        data = self._raw[self._dirtyoffset:]
        if not data:
            return

        repo = self._repo

        try:
            lock = repo.wlock(wait=False)
        except error.LockError:
            repo.ui.log('tagscache', 'not writing .hg/cache/%s because '
                        'lock cannot be acquired\n' % (_fnodescachefile))
            return

        try:
            f = repo.cachevfs.open(_fnodescachefile, 'ab')
            try:
                # if the file has been truncated
                actualoffset = f.tell()
                if actualoffset < self._dirtyoffset:
                    self._dirtyoffset = actualoffset
                    data = self._raw[self._dirtyoffset:]
                f.seek(self._dirtyoffset)
                f.truncate()
                repo.ui.log('tagscache',
                            'writing %d bytes to cache/%s\n' % (
                            len(data), _fnodescachefile))
                f.write(data)
                self._dirtyoffset = None
            finally:
                f.close()
        except (IOError, OSError) as inst:
            repo.ui.log('tagscache',
                        "couldn't write cache/%s: %s\n" % (
                            _fnodescachefile, stringutil.forcebytestr(inst)))
        finally:
            lock.release()

43076:2372284d9457

    error,
    match as matchmod,
    scmutil,
    util,
)
from .utils import stringutil

# Tags computation can be expensive and caches exist to make it fast in
# the common case.
#
# The "hgtagsfnodes1" cache file caches the .hgtags filenode values for

# Tags are written sorted by tag name.
#
# Tags associated with multiple changesets have an entry for each changeset.
# The most recent changeset (in terms of revlog ordering for the head
# setting it) for each tag is last.


def fnoderevs(ui, repo, revs):
    """return the list of '.hgtags' fnodes used in a set revisions

    This is returned as list of unique fnodes. We use a list instead of a set

    nodes = [tonode(r) for r in revs]
    fnodes = _getfnodes(ui, repo, nodes)
    fnodes = _filterfnodes(fnodes, nodes)
    return fnodes


def _nulltonone(value):
    """convert nullid to None

    For tag value, nullid means "deleted". This small utility function helps
    translating that to None."""
    if value == nullid:
        return None
    return value


def difftags(ui, repo, oldfnodes, newfnodes):
    """list differences between tags expressed in two set of file-nodes

    The list contains entries in the form: (tagname, oldvalue, new value).

        old = _nulltonone(old)
        if old is not None:
            entries.append((tag, old, None))
    entries.sort()
    return entries


def writediff(fp, difflist):
    """write tags diff information to a file.

    Data are stored with a line based format:

            fp.write(remove % (old, tag))
        else:
            fp.write(updateold % (old, tag))
            fp.write(updatenew % (new, tag))


def findglobaltags(ui, repo):
    '''Find global tags in a repo: return a tagsmap

    tagsmap: tag name to (node, hist) 2-tuples.

        alltags = {}
        _updatetags(cachetags, alltags)
        return alltags

    for head in reversed(heads):  # oldest to newest
        assert (
            head in repo.changelog.nodemap
        ), "tag cache returned bogus head %s" % short(head)
    fnodes = _filterfnodes(tagfnode, reversed(heads))
    alltags = _tagsfromfnodes(ui, repo, fnodes)

    # and update the cache (if necessary)
    if shouldwrite:
        _writetagcache(ui, repo, valid, alltags)
    return alltags


def _filterfnodes(tagfnode, nodes):
    """return a list of unique fnodes

    The order of this list matches the order of "nodes". Preserving this order

        if fnode and fnode not in seen:
            seen.add(fnode)
            fnodes.append(fnode)
    return fnodes


def _tagsfromfnodes(ui, repo, fnodes):
    """return a tagsmap from a list of file-node

    tagsmap: tag name to (node, hist) 2-tuples.

            fctx = fctx.filectx(fnode)
        filetags = _readtags(ui, repo, fctx.data().splitlines(), fctx)
        _updatetags(filetags, alltags)
    return alltags


def readlocaltags(ui, repo, alltags, tagtypes):
    '''Read local tags in repo. Update alltags and tagtypes.'''
    try:
        data = repo.vfs.read("localtags")
    except IOError as inst:

        return

    # localtags is in the local encoding; re-encode to UTF-8 on
    # input for consistency with the rest of this module.
    filetags = _readtags(
        ui, repo, data.splitlines(), "localtags", recode=encoding.fromlocal
    )

    # remove tags pointing to invalid nodes
    cl = repo.changelog
    for t in list(filetags):
        try:
            cl.rev(filetags[t][0])
        except (LookupError, ValueError):
            del filetags[t]

    _updatetags(filetags, alltags, 'local', tagtypes)


def _readtaghist(ui, repo, lines, fn, recode=None, calcnodelines=False):
    '''Read tag definitions from a file (or any source of lines).

    This function returns two sortdicts with similar information:

        if name not in bintaghist:
            bintaghist[name] = []
        bintaghist[name].append(nodebin)
    return bintaghist, hextaglines


def _readtags(ui, repo, lines, fn, recode=None, calcnodelines=False):
    '''Read tag definitions from a file (or any source of lines).

    Returns a mapping from tag name to (node, hist).

    "node" is the node id from the last line read for that name. "hist"
    is the list of node ids previously associated with it (in file order).
    All node ids are binary, not hex.
    '''
    filetags, nodelines = _readtaghist(
        ui, repo, lines, fn, recode=recode, calcnodelines=calcnodelines
    )
    # util.sortdict().__setitem__ is much slower at replacing then inserting
    # new entries. The difference can matter if there are thousands of tags.
    # Create a new sortdict to avoid the performance penalty.
    newtags = util.sortdict()
    for tag, taghist in filetags.items():
        newtags[tag] = (taghist[-1], taghist[:-1])
    return newtags


def _updatetags(filetags, alltags, tagtype=None, tagtypes=None):
    """Incorporate the tag info read from one file into dictionnaries

    The first one, 'alltags', is a "tagmaps" (see 'findglobaltags' for details).

        #  it supersedes us OR
        #  mutual supersedes and it has a higher rank
        # otherwise we win because we're tip-most
        anode, ahist = nodehist
        bnode, bhist = alltags[name]
        if (
            bnode != anode
            and anode in bhist
            and (bnode not in ahist or len(bhist) > len(ahist))
        ):
            anode = bnode
        elif tagtype is not None:
            tagtypes[name] = tagtype
        ahist.extend([n for n in bhist if n not in ahist])
        alltags[name] = anode, ahist


def _filename(repo):
    """name of a tagcache file for a given repo or repoview"""
    filename = 'tags2'
    if repo.filtername:
        filename = '%s-%s' % (filename, repo.filtername)
    return filename


def _readtagcache(ui, repo):
    '''Read the tag cache.

    Returns a tuple (heads, fnodes, validinfo, cachetags, shouldwrite).

    # Case 1 (common): tip is the same, so nothing has changed.
    # (Unchanged tip trivially means no changesets have been added.
    # But, thanks to localrepository.destroyed(), it also means none
    # have been destroyed by strip or rollback.)
    if (
        cacherev == tiprev
        and cachenode == tipnode
        and cachehash == scmutil.filteredhash(repo, tiprev)
    ):
        tags = _readtags(ui, repo, cachelines, cachefile.name)
        cachefile.close()
        return (None, None, None, tags, False)
    if cachefile:
        cachefile.close()  # ignore rest of file

    valid = (tiprev, tipnode, scmutil.filteredhash(repo, tiprev))

    repoheads = repo.heads()
    # Case 2 (uncommon): empty repo; get out quickly and don't bother

    if not len(repo.file('.hgtags')):
        # No tags have ever been committed, so we can avoid a
        # potentially expensive search.
        return ([], {}, valid, None, True)

    # Now we have to lookup the .hgtags filenode for every new head.
    # This is the most expensive part of finding tags, so performance
    # depends primarily on the size of newheads.  Worst case: no cache
    # file, so newheads == repoheads.
    # Reversed order helps the cache ('repoheads' is in descending order)
    cachefnode = _getfnodes(ui, repo, reversed(repoheads))

    # Caller has to iterate over all heads, but can use the filenodes in
    # cachefnode to get to each .hgtags revision quickly.
    return (repoheads, cachefnode, valid, None, True)


def _getfnodes(ui, repo, nodes):
    """return .hgtags fnodes for a list of changeset nodes

    Return value is a {node: fnode} mapping. There will be no entry for nodes

            cachefnode[node] = fnode

    fnodescache.write()

    duration = util.timer() - starttime
    ui.log(
        'tagscache',
        '%d/%d cache hits/lookups in %0.4f seconds\n',
        fnodescache.hitcount,
        fnodescache.lookupcount,
        duration,
    )
    return cachefnode


def _writetagcache(ui, repo, valid, cachetags):
    filename = _filename(repo)
    try:
        cachefile = repo.cachevfs(filename, 'w', atomictemp=True)
    except (OSError, IOError):
        return

    ui.log(
        'tagscache',
        'writing .hg/cache/%s with %d tags\n',
        filename,
        len(cachetags),
    )

    if valid[2]:
        cachefile.write('%d %s %s\n' % (valid[0], hex(valid[1]), hex(valid[2])))
    else:
        cachefile.write('%d %s\n' % (valid[0], hex(valid[1])))

    try:
        cachefile.close()
    except (OSError, IOError):
        pass


def tag(repo, names, node, message, local, user, date, editor=False):
    '''tag a revision with one or more symbolic names.

    names is a list of strings or, when adding a single tag, names may be a
    string.

    date: date tuple to use if committing'''

    if not local:
        m = matchmod.exact(['.hgtags'])
        if any(repo.status(match=m, unknown=True, ignored=True)):
            raise error.Abort(
                _('working copy of .hgtags is changed'),
                hint=_('please commit .hgtags manually'),
            )

    with repo.wlock():
        repo.tags()  # instantiate the cache
        _tag(repo, names, node, message, local, user, date, editor=editor)


def _tag(
    repo, names, node, message, local, user, date, extra=None, editor=False
):
    if isinstance(names, bytes):
        names = (names,)

    branches = repo.branchmap()
    for name in names:
        repo.hook('pretag', throw=True, node=hex(node), tag=name, local=local)
        if name in branches:
            repo.ui.warn(
                _("warning: tag %s conflicts with existing" " branch name\n")
                % name
            )

    def writetags(fp, names, munge, prevtags):
        fp.seek(0, io.SEEK_END)
        if prevtags and not prevtags.endswith('\n'):
            fp.write('\n')

            if munge:
                m = munge(name)
            else:
                m = name

            if repo._tagscache.tagtypes and name in repo._tagscache.tagtypes:
                old = repo.tags().get(name, nullid)
                fp.write('%s %s\n' % (hex(old), m))
            fp.write('%s %s\n' % (hex(node), m))
        fp.close()

    if '.hgtags' not in repo.dirstate:
        repo[None].add(['.hgtags'])

    m = matchmod.exact(['.hgtags'])
    tagnode = repo.commit(
        message, user, date, extra=extra, match=m, editor=editor
    )

    for name in names:
        repo.hook('tag', node=hex(node), tag=name, local=local)

    return tagnode


_fnodescachefile = 'hgtagsfnodes1'
_fnodesrecsize = 4 + 20  # changeset fragment + filenode
_fnodesmissingrec = '\xff' * 24


class hgtagsfnodescache(object):
    """Persistent cache mapping revisions to .hgtags filenodes.

    The cache is an array of records. Each item in the array corresponds to

    only parsed on read.

    Instances behave like lists. ``c[i]`` works where i is a rev or
    changeset node. Missing indexes are populated automatically on access.
    """

    def __init__(self, repo):
        assert repo.filtername is None

        self._repo = repo

        # Only for reporting purposes.
        self.lookupcount = 0
        self.hitcount = 0

        try:
            data = repo.cachevfs.read(_fnodescachefile)
        except (OSError, IOError):
            data = ""

        rev = ctx.rev()

        self.lookupcount += 1

        offset = rev * _fnodesrecsize
        record = '%s' % self._raw[offset : offset + _fnodesrecsize]
        properprefix = node[0:4]

        # Validate and return existing entry.
        if record != _fnodesmissingrec:
            fileprefix = record[0:4]

        self._writeentry(ctx.rev() * _fnodesrecsize, node[0:4], fnode)

    def _writeentry(self, offset, prefix, fnode):
        # Slices on array instances only accept other array.
        entry = bytearray(prefix + fnode)
        self._raw[offset : offset + _fnodesrecsize] = entry
        # self._dirtyoffset could be None.
        self._dirtyoffset = min(self._dirtyoffset or 0, offset or 0)

    def write(self):
        """Perform all necessary writes to cache file.

        not be obtained.
        """
        if self._dirtyoffset is None:
            return

        data = self._raw[self._dirtyoffset :]
        if not data:
            return

        repo = self._repo

        try:
            lock = repo.wlock(wait=False)
        except error.LockError:
            repo.ui.log(
                'tagscache',
                'not writing .hg/cache/%s because '
                'lock cannot be acquired\n' % _fnodescachefile,
            )
            return

        try:
            f = repo.cachevfs.open(_fnodescachefile, 'ab')
            try:
                # if the file has been truncated
                actualoffset = f.tell()
                if actualoffset < self._dirtyoffset:
                    self._dirtyoffset = actualoffset
                    data = self._raw[self._dirtyoffset :]
                f.seek(self._dirtyoffset)
                f.truncate()
                repo.ui.log(
                    'tagscache',
                    'writing %d bytes to cache/%s\n'
                    % (len(data), _fnodescachefile),
                )
                f.write(data)
                self._dirtyoffset = None
            finally:
                f.close()
        except (IOError, OSError) as inst:
            repo.ui.log(
                'tagscache',
                "couldn't write cache/%s: %s\n"
                % (_fnodescachefile, stringutil.forcebytestr(inst)),
            )
        finally:
            lock.release()