view mercurial/changelog.py @ 48687:f8f2ecdde4b5

branchmap: skip obsolete revisions while computing heads

It's time to make this part of core Mercurial obsolescence-aware.

Not considering obsolete revisions when computing heads is clearly what
Mercurial should do. But there are a couple of small issues:

- Let's say tip of the repo is obsolete. There are two ways of finding tiprev
  for branchcache (both are in use): looking at input data for update() and
  looking at computed heads after update(). Previously, repo tip would be
  tiprev of the branchcache. With this patch, an obsolete revision can no
  longer be tiprev. And depending on what way we use for finding tiprev (input
  data vs computed heads) we'll get a different result. This is relevant when
  recomputing cache key from cache contents, and may lead to updating cache for
  obsolete revisions multiple times (not from scratch, because it still would
  be considered valid for a subset of revisions in the repo).

- If all commits on a branch are obsolete, the branchcache will include that
  branch, but the list of heads will be empty (that's why there's now `if not
  heads` when recomputing tiprev/tipnode from cache contents). Having an entry
  for every branch is currently required for notify extension (and
  test-notify.t to pass), because notify doesn't handle revsets in its
  subscription config very well and will throw an error if e.g. a branch
  doesn't exist.

- Cloning static HTTP repos may try to stat() a non-existent obsstore file. The
  issue is that we now care about obsolescence during clone, but statichttpvfs
  doesn't implement a stat method, so a regular vfs.stat() is used, and it
  assumes that file is local and calls os.stat().  During a clone, we're trying
  to stat() .hg/store/obsstore, but in static HTTP case we provide a literal
  URL to the obsstore file on the remote as if it were a local file path. On
  windows it actually results in a failure in test-static-http.t.

The first issue is going to be addressed in a series dedicated to making sure
branchcache is properly and timely written on disk (it wasn't perfect even
before this patch, but there aren't enough tests to demonstrate that). The
second issue will be addressed in a future patch for notify extension that will
make it not raise an exception if a branch doesn't exist. And the third one was
partially addressed in the previous patch in this series and will be properly
fixed in a future patch when this series is accepted.

filteredhash() grows a keyword argument to make sure that branchcache is also
invalidated when there are new obsolete revisions in its repo view. This way
the on-disk cache format is unchanged and compatible between versions (although
it will obviously be recomputed when switching versions before/after this patch
and the repo has obsolete revisions).

There's one test that uses plain `hg up` without arguments while updated to a
pruned commit. To make this test pass, simply return current working directory
parent. Later in this series this code will be replaced by what prune command
does: updating to the closest non-obsolete ancestor.

Test changes:

test-branch-change.t: update branch head and cache update message. The head of
default listed in hg heads is changed because revision 2 was rewritten as 7,
and 1 is the closest ancestor on the same branch, so it's the head of default
now.

The cache invalidation message appears now because of the cache hash change,
since we're now accounting for obsolete revisions. Here's some context:

"served.hidden" repo filter means everything is visible (no filtered
revisions), so before this series branch2-served.hidden file would not contain
any cache hash, only revnum and node. Now it also has a hash when there are
obsolete changesets in the repo. The command that the message appears for is
changing branch of 5 and 6, which are now obsolete, so the cache hash changes.

In general, when cache is simply out-of-date, it can be updated using the old
version as a base. But if cache hash differs, then the cache for that
particular repo filter is recomputed (at least with the current
implementation). This is what happens here.

test-obsmarker-template.t: the pull reports 2 heads changed, but after that the
repo correctly sees only 1. The new message could be better, but it's still an
improvement over the previous one where hg pull suggested merging with an
obsolete revision.

test-obsolete.t: we can see these revisions in hg log --hidden, but they
shouldn't be considered heads even with --hidden.

test-rebase-obsolete{,2}.t: there were new heads created previously after
making new orphan changesets, but they weren't detected. Now we are properly
detecting and reporting them.

test-rebase-obsolete4.t: there's only one head now because the other head is
pruned and was falsely reported before.

test-static-http.t: add obsstore to the list of requested files. This file
doesn't exist on the remotes, but clients want it anyway (they get 404). This
is fine, because there are other nonexistent files that clients request, like
.hg/bookmarks or .hg/cache/tags2-served.

Differential Revision: https://phab.mercurial-scm.org/D12097

# changelog.py - changelog class for mercurial
#
# Copyright 2005-2007 Olivia 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 __future__ import absolute_import

from .i18n import _
from .node import (
    bin,
    hex,
)
from .thirdparty import attr

from . import (
    encoding,
    error,
    metadata,
    pycompat,
    revlog,
)
from .utils import (
    dateutil,
    stringutil,
)
from .revlogutils import (
    constants as revlog_constants,
    flagutil,
)

_defaultextra = {b'branch': b'default'}


def _string_escape(text):
    """
    >>> from .pycompat import bytechr as chr
    >>> d = {b'nl': chr(10), b'bs': chr(92), b'cr': chr(13), b'nul': chr(0)}
    >>> s = b"ab%(nl)scd%(bs)s%(bs)sn%(nul)s12ab%(cr)scd%(bs)s%(nl)s" % d
    >>> s
    'ab\\ncd\\\\\\\\n\\x0012ab\\rcd\\\\\\n'
    >>> res = _string_escape(s)
    >>> s == _string_unescape(res)
    True
    """
    # subset of the string_escape codec
    text = (
        text.replace(b'\\', b'\\\\')
        .replace(b'\n', b'\\n')
        .replace(b'\r', b'\\r')
    )
    return text.replace(b'\0', b'\\0')


def _string_unescape(text):
    if b'\\0' in text:
        # fix up \0 without getting into trouble with \\0
        text = text.replace(b'\\\\', b'\\\\\n')
        text = text.replace(b'\\0', b'\0')
        text = text.replace(b'\n', b'')
    return stringutil.unescapestr(text)


def decodeextra(text):
    """
    >>> from .pycompat import bytechr as chr
    >>> sorted(decodeextra(encodeextra({b'foo': b'bar', b'baz': chr(0) + b'2'})
    ...                    ).items())
    [('baz', '\\x002'), ('branch', 'default'), ('foo', 'bar')]
    >>> sorted(decodeextra(encodeextra({b'foo': b'bar',
    ...                                 b'baz': chr(92) + chr(0) + b'2'})
    ...                    ).items())
    [('baz', '\\\\\\x002'), ('branch', 'default'), ('foo', 'bar')]
    """
    extra = _defaultextra.copy()
    for l in text.split(b'\0'):
        if l:
            k, v = _string_unescape(l).split(b':', 1)
            extra[k] = v
    return extra


def encodeextra(d):
    # keys must be sorted to produce a deterministic changelog entry
    items = [_string_escape(b'%s:%s' % (k, d[k])) for k in sorted(d)]
    return b"\0".join(items)


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

    def end(self):
        return self._end

    def tell(self):
        return self.offset

    def flush(self):
        pass

    @property
    def closed(self):
        return self.fp.closed

    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 = b""
        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, b"".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(bytes(s))
        self.offset += len(s)
        self._end += len(s)

    def __enter__(self):
        self.fp.__enter__()
        return self

    def __exit__(self, *args):
        return self.fp.__exit__(*args)


class _divertopener(object):
    def __init__(self, opener, target):
        self._opener = opener
        self._target = target

    def __call__(self, name, mode=b'r', checkambig=False, **kwargs):
        if name != self._target:
            return self._opener(name, mode, **kwargs)
        return self._opener(name + b".a", mode, **kwargs)

    def __getattr__(self, attr):
        return getattr(self._opener, attr)


def _delayopener(opener, target, buf):
    """build an opener that stores chunks in 'buf' instead of 'target'"""

    def _delay(name, mode=b'r', checkambig=False, **kwargs):
        if name != target:
            return opener(name, mode, **kwargs)
        assert not kwargs
        return appender(opener, name, mode, buf)

    return _delay


@attr.s
class _changelogrevision(object):
    # Extensions might modify _defaultextra, so let the constructor below pass
    # it in
    extra = attr.ib()
    manifest = attr.ib()
    user = attr.ib(default=b'')
    date = attr.ib(default=(0, 0))
    files = attr.ib(default=attr.Factory(list))
    filesadded = attr.ib(default=None)
    filesremoved = attr.ib(default=None)
    p1copies = attr.ib(default=None)
    p2copies = attr.ib(default=None)
    description = attr.ib(default=b'')
    branchinfo = attr.ib(default=(_defaultextra[b'branch'], False))


class changelogrevision(object):
    """Holds results of a parsed changelog revision.

    Changelog revisions consist of multiple pieces of data, including
    the manifest node, user, and date. This object exposes a view into
    the parsed object.
    """

    __slots__ = (
        '_offsets',
        '_text',
        '_sidedata',
        '_cpsd',
        '_changes',
    )

    def __new__(cls, cl, text, sidedata, cpsd):
        if not text:
            return _changelogrevision(extra=_defaultextra, manifest=cl.nullid)

        self = super(changelogrevision, cls).__new__(cls)
        # We could return here and implement the following as an __init__.
        # But doing it here is equivalent and saves an extra function call.

        # 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

        nl1 = text.index(b'\n')
        nl2 = text.index(b'\n', nl1 + 1)
        nl3 = text.index(b'\n', nl2 + 1)

        # The list of files may be empty. Which means nl3 is the first of the
        # double newline that precedes the description.
        if text[nl3 + 1 : nl3 + 2] == b'\n':
            doublenl = nl3
        else:
            doublenl = text.index(b'\n\n', nl3 + 1)

        self._offsets = (nl1, nl2, nl3, doublenl)
        self._text = text
        self._sidedata = sidedata
        self._cpsd = cpsd
        self._changes = None

        return self

    @property
    def manifest(self):
        return bin(self._text[0 : self._offsets[0]])

    @property
    def user(self):
        off = self._offsets
        return encoding.tolocal(self._text[off[0] + 1 : off[1]])

    @property
    def _rawdate(self):
        off = self._offsets
        dateextra = self._text[off[1] + 1 : off[2]]
        return dateextra.split(b' ', 2)[0:2]

    @property
    def _rawextra(self):
        off = self._offsets
        dateextra = self._text[off[1] + 1 : off[2]]
        fields = dateextra.split(b' ', 2)
        if len(fields) != 3:
            return None

        return fields[2]

    @property
    def date(self):
        raw = self._rawdate
        time = float(raw[0])
        # Various tools did silly things with the timezone.
        try:
            timezone = int(raw[1])
        except ValueError:
            timezone = 0

        return time, timezone

    @property
    def extra(self):
        raw = self._rawextra
        if raw is None:
            return _defaultextra

        return decodeextra(raw)

    @property
    def changes(self):
        if self._changes is not None:
            return self._changes
        if self._cpsd:
            changes = metadata.decode_files_sidedata(self._sidedata)
        else:
            changes = metadata.ChangingFiles(
                touched=self.files or (),
                added=self.filesadded or (),
                removed=self.filesremoved or (),
                p1_copies=self.p1copies or {},
                p2_copies=self.p2copies or {},
            )
        self._changes = changes
        return changes

    @property
    def files(self):
        if self._cpsd:
            return sorted(self.changes.touched)
        off = self._offsets
        if off[2] == off[3]:
            return []

        return self._text[off[2] + 1 : off[3]].split(b'\n')

    @property
    def filesadded(self):
        if self._cpsd:
            return self.changes.added
        else:
            rawindices = self.extra.get(b'filesadded')
        if rawindices is None:
            return None
        return metadata.decodefileindices(self.files, rawindices)

    @property
    def filesremoved(self):
        if self._cpsd:
            return self.changes.removed
        else:
            rawindices = self.extra.get(b'filesremoved')
        if rawindices is None:
            return None
        return metadata.decodefileindices(self.files, rawindices)

    @property
    def p1copies(self):
        if self._cpsd:
            return self.changes.copied_from_p1
        else:
            rawcopies = self.extra.get(b'p1copies')
        if rawcopies is None:
            return None
        return metadata.decodecopies(self.files, rawcopies)

    @property
    def p2copies(self):
        if self._cpsd:
            return self.changes.copied_from_p2
        else:
            rawcopies = self.extra.get(b'p2copies')
        if rawcopies is None:
            return None
        return metadata.decodecopies(self.files, rawcopies)

    @property
    def description(self):
        return encoding.tolocal(self._text[self._offsets[3] + 2 :])

    @property
    def branchinfo(self):
        extra = self.extra
        return encoding.tolocal(extra.get(b"branch")), b'close' in extra


class changelog(revlog.revlog):
    def __init__(self, opener, trypending=False, concurrencychecker=None):
        """Load a changelog revlog using an opener.

        If ``trypending`` is true, we attempt to load the index from a
        ``00changelog.i.a`` file instead of the default ``00changelog.i``.
        The ``00changelog.i.a`` file contains index (and possibly inline
        revision) data for a transaction that hasn't been finalized yet.
        It exists in a separate file to facilitate readers (such as
        hooks processes) accessing data before a transaction is finalized.

        ``concurrencychecker`` will be passed to the revlog init function, see
        the documentation there.
        """
        revlog.revlog.__init__(
            self,
            opener,
            target=(revlog_constants.KIND_CHANGELOG, None),
            radix=b'00changelog',
            checkambig=True,
            mmaplargeindex=True,
            persistentnodemap=opener.options.get(b'persistent-nodemap', False),
            concurrencychecker=concurrencychecker,
            trypending=trypending,
        )

        if self._initempty and (self._format_version == revlog.REVLOGV1):
            # changelogs don't benefit from generaldelta.

            self._format_flags &= ~revlog.FLAG_GENERALDELTA
            self._generaldelta = False

        # Delta chains for changelogs tend to be very small because entries
        # tend to be small and don't delta well with each. So disable delta
        # chains.
        self._storedeltachains = False

        self._realopener = opener
        self._delayed = False
        self._delaybuf = None
        self._divert = False
        self._filteredrevs = frozenset()
        self._filteredrevs_hashcache = {}
        self._copiesstorage = opener.options.get(b'copies-storage')

    @property
    def filteredrevs(self):
        return self._filteredrevs

    @filteredrevs.setter
    def filteredrevs(self, val):
        # Ensure all updates go through this function
        assert isinstance(val, frozenset)
        self._filteredrevs = val
        self._filteredrevs_hashcache = {}

    def _write_docket(self, tr):
        if not self._delayed:
            super(changelog, self)._write_docket(tr)

    def delayupdate(self, tr):
        """delay visibility of index updates to other readers"""
        if self._docket is None and not self._delayed:
            if len(self) == 0:
                self._divert = True
                if self._realopener.exists(self._indexfile + b'.a'):
                    self._realopener.unlink(self._indexfile + b'.a')
                self.opener = _divertopener(self._realopener, self._indexfile)
            else:
                self._delaybuf = []
                self.opener = _delayopener(
                    self._realopener, self._indexfile, self._delaybuf
                )
            self._segmentfile.opener = self.opener
            self._segmentfile_sidedata.opener = self.opener
        self._delayed = True
        tr.addpending(b'cl-%i' % id(self), self._writepending)
        tr.addfinalize(b'cl-%i' % id(self), self._finalize)

    def _finalize(self, tr):
        """finalize index updates"""
        self._delayed = False
        self.opener = self._realopener
        self._segmentfile.opener = self.opener
        self._segmentfile_sidedata.opener = self.opener
        # move redirected index data back into place
        if self._docket is not None:
            self._write_docket(tr)
        elif self._divert:
            assert not self._delaybuf
            tmpname = self._indexfile + b".a"
            nfile = self.opener.open(tmpname)
            nfile.close()
            self.opener.rename(tmpname, self._indexfile, checkambig=True)
        elif self._delaybuf:
            fp = self.opener(self._indexfile, b'a', checkambig=True)
            fp.write(b"".join(self._delaybuf))
            fp.close()
            self._delaybuf = None
        self._divert = False
        # split when we're done
        self._enforceinlinesize(tr)

    def _writepending(self, tr):
        """create a file containing the unfinalized state for
        pretxnchangegroup"""
        if self._docket:
            return self._docket.write(tr, pending=True)
        if self._delaybuf:
            # make a temporary copy of the index
            fp1 = self._realopener(self._indexfile)
            pendingfilename = self._indexfile + b".a"
            # register as a temp file to ensure cleanup on failure
            tr.registertmp(pendingfilename)
            # write existing data
            fp2 = self._realopener(pendingfilename, b"w")
            fp2.write(fp1.read())
            # add pending data
            fp2.write(b"".join(self._delaybuf))
            fp2.close()
            # switch modes so finalize can simply rename
            self._delaybuf = None
            self._divert = True
            self.opener = _divertopener(self._realopener, self._indexfile)
            self._segmentfile.opener = self.opener
            self._segmentfile_sidedata.opener = self.opener

        if self._divert:
            return True

        return False

    def _enforceinlinesize(self, tr):
        if not self._delayed:
            revlog.revlog._enforceinlinesize(self, tr)

    def read(self, nodeorrev):
        """Obtain data from a parsed changelog revision.

        Returns a 6-tuple of:

           - manifest node in binary
           - author/user as a localstr
           - date as a 2-tuple of (time, timezone)
           - list of files
           - commit message as a localstr
           - dict of extra metadata

        Unless you need to access all fields, consider calling
        ``changelogrevision`` instead, as it is faster for partial object
        access.
        """
        d = self._revisiondata(nodeorrev)
        sidedata = self.sidedata(nodeorrev)
        copy_sd = self._copiesstorage == b'changeset-sidedata'
        c = changelogrevision(self, d, sidedata, copy_sd)
        return (c.manifest, c.user, c.date, c.files, c.description, c.extra)

    def changelogrevision(self, nodeorrev):
        """Obtain a ``changelogrevision`` for a node or revision."""
        text = self._revisiondata(nodeorrev)
        sidedata = self.sidedata(nodeorrev)
        return changelogrevision(
            self, text, sidedata, self._copiesstorage == b'changeset-sidedata'
        )

    def readfiles(self, nodeorrev):
        """
        short version of read that only returns the files modified by the cset
        """
        text = self.revision(nodeorrev)
        if not text:
            return []
        last = text.index(b"\n\n")
        l = text[:last].split(b'\n')
        return l[3:]

    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.StorageError(_(b"empty username"))
        if b"\n" in user:
            raise error.StorageError(
                _(b"username %r contains a newline") % pycompat.bytestr(user)
            )

        desc = stripdesc(desc)

        if date:
            parseddate = b"%d %d" % dateutil.parsedate(date)
        else:
            parseddate = b"%d %d" % dateutil.makedate()
        if extra:
            branch = extra.get(b"branch")
            if branch in (b"default", b""):
                del extra[b"branch"]
            elif branch in (b".", b"null", b"tip"):
                raise error.StorageError(
                    _(b'the name \'%s\' is reserved') % branch
                )
        sortedfiles = sorted(files.touched)
        flags = 0
        sidedata = None
        if self._copiesstorage == b'changeset-sidedata':
            if files.has_copies_info:
                flags |= flagutil.REVIDX_HASCOPIESINFO
            sidedata = metadata.encode_files_sidedata(files)

        if extra:
            extra = encodeextra(extra)
            parseddate = b"%s %s" % (parseddate, extra)
        l = [hex(manifest), user, parseddate] + sortedfiles + [b"", desc]
        text = b"\n".join(l)
        rev = self.addrevision(
            text, transaction, len(self), p1, p2, sidedata=sidedata, flags=flags
        )
        return self.node(rev)

    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."""
        return self.changelogrevision(rev).branchinfo

    def _nodeduplicatecallback(self, transaction, rev):
        # keep track of revisions that got "re-added", eg: unbunde of know rev.
        #
        # We track them in a list to preserve their order from the source bundle
        duplicates = transaction.changes.setdefault(b'revduplicates', [])
        duplicates.append(rev)