view mercurial/filelog.py @ 43913:4b7d5d10c45d

exchange: ensure all outgoing subrepo references are present before pushing

We've run into occasional problems with people committing a repo, and then
amending or rebasing in the subrepo.  That makes it so that the revision in the
parent can't be checked out, and the problem gets propagated on push.  Mercurial
already tries to defend against this sort of dangling reference by pushing *all*
subrepo revisions first.  This reuses the checks that trigger warnings in
`hg verify` to bail on the push unless using `--force`.

I thought about putting this on the server side, but at that point, all of the
data has been transferred, only to bail out.  Additionally, SCM Manager hosts
subrepos in a location that isn't nested in the parent, so normal subrepo code
would complain that the subrepo is missing when run on the server.

Because the push command pushes subrepos before calling this exchange code, a
subrepo will be pushed before the parent is verified.  Not great, but no
dangling references are exchanged, so it solves the problem.  This code isn't in
the loop that pushes the subrepos because:

  1) the list of outgoing revisions is needed to limit the scope of the check
  2) the loop only accesses the current revision, and therefore can miss
     subrepos that were dropped in previous commits
  3) this code is called when pushing a subrepo, so the protection is recursive

I'm not sure if there's a cheap check for the list of files in the outgoing
bundle.  If there is, that would provide a fast path to bypass this check for
people not using subrepos (or if no subrepo changes were made).  There's
probably also room for verifying other references like tags.  But since that
doesn't break checkouts, it's much less of a problem.

Differential Revision: https://phab.mercurial-scm.org/D7616

# filelog.py - file history 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 __future__ import absolute_import

from .i18n import _
from .node import (
    nullid,
    nullrev,
)
from . import (
    error,
    revlog,
)
from .interfaces import (
    repository,
    util as interfaceutil,
)
from .utils import storageutil


@interfaceutil.implementer(repository.ifilestorage)
class filelog(object):
    def __init__(self, opener, path):
        self._revlog = revlog.revlog(
            opener, b'/'.join((b'data', path + b'.i')), censorable=True
        )
        # Full name of the user visible file, relative to the repository root.
        # Used by LFS.
        self._revlog.filename = path

    def __len__(self):
        return len(self._revlog)

    def __iter__(self):
        return self._revlog.__iter__()

    def hasnode(self, node):
        if node in (nullid, nullrev):
            return False

        try:
            self._revlog.rev(node)
            return True
        except (TypeError, ValueError, IndexError, error.LookupError):
            return False

    def revs(self, start=0, stop=None):
        return self._revlog.revs(start=start, stop=stop)

    def parents(self, node):
        return self._revlog.parents(node)

    def parentrevs(self, rev):
        return self._revlog.parentrevs(rev)

    def rev(self, node):
        return self._revlog.rev(node)

    def node(self, rev):
        return self._revlog.node(rev)

    def lookup(self, node):
        return storageutil.fileidlookup(
            self._revlog, node, self._revlog.indexfile
        )

    def linkrev(self, rev):
        return self._revlog.linkrev(rev)

    def commonancestorsheads(self, node1, node2):
        return self._revlog.commonancestorsheads(node1, node2)

    # Used by dagop.blockdescendants().
    def descendants(self, revs):
        return self._revlog.descendants(revs)

    def heads(self, start=None, stop=None):
        return self._revlog.heads(start, stop)

    # Used by hgweb, children extension.
    def children(self, node):
        return self._revlog.children(node)

    def iscensored(self, rev):
        return self._revlog.iscensored(rev)

    def revision(self, node, _df=None, raw=False):
        return self._revlog.revision(node, _df=_df, raw=raw)

    def rawdata(self, node, _df=None):
        return self._revlog.rawdata(node, _df=_df)

    def emitrevisions(
        self,
        nodes,
        nodesorder=None,
        revisiondata=False,
        assumehaveparentrevisions=False,
        deltamode=repository.CG_DELTAMODE_STD,
    ):
        return self._revlog.emitrevisions(
            nodes,
            nodesorder=nodesorder,
            revisiondata=revisiondata,
            assumehaveparentrevisions=assumehaveparentrevisions,
            deltamode=deltamode,
        )

    def addrevision(
        self,
        revisiondata,
        transaction,
        linkrev,
        p1,
        p2,
        node=None,
        flags=revlog.REVIDX_DEFAULT_FLAGS,
        cachedelta=None,
    ):
        return self._revlog.addrevision(
            revisiondata,
            transaction,
            linkrev,
            p1,
            p2,
            node=node,
            flags=flags,
            cachedelta=cachedelta,
        )

    def addgroup(
        self,
        deltas,
        linkmapper,
        transaction,
        addrevisioncb=None,
        maybemissingparents=False,
    ):
        if maybemissingparents:
            raise error.Abort(
                _(
                    b'revlog storage does not support missing '
                    b'parents write mode'
                )
            )

        return self._revlog.addgroup(
            deltas, linkmapper, transaction, addrevisioncb=addrevisioncb
        )

    def getstrippoint(self, minlink):
        return self._revlog.getstrippoint(minlink)

    def strip(self, minlink, transaction):
        return self._revlog.strip(minlink, transaction)

    def censorrevision(self, tr, node, tombstone=b''):
        return self._revlog.censorrevision(tr, node, tombstone=tombstone)

    def files(self):
        return self._revlog.files()

    def read(self, node):
        return storageutil.filtermetadata(self.revision(node))

    def add(self, text, meta, transaction, link, p1=None, p2=None):
        if meta or text.startswith(b'\1\n'):
            text = storageutil.packmeta(meta, text)
        return self.addrevision(text, transaction, link, p1, p2)

    def renamed(self, node):
        return storageutil.filerevisioncopied(self, node)

    def size(self, rev):
        """return the size of a given revision"""

        # for revisions with renames, we have to go the slow way
        node = self.node(rev)
        if self.renamed(node):
            return len(self.read(node))
        if self.iscensored(rev):
            return 0

        # XXX if self.read(node).startswith("\1\n"), this returns (size+4)
        return self._revlog.size(rev)

    def cmp(self, node, text):
        """compare text with a given file revision

        returns True if text is different than what is stored.
        """
        return not storageutil.filedataequivalent(self, node, text)

    def verifyintegrity(self, state):
        return self._revlog.verifyintegrity(state)

    def storageinfo(
        self,
        exclusivefiles=False,
        sharedfiles=False,
        revisionscount=False,
        trackedsize=False,
        storedsize=False,
    ):
        return self._revlog.storageinfo(
            exclusivefiles=exclusivefiles,
            sharedfiles=sharedfiles,
            revisionscount=revisionscount,
            trackedsize=trackedsize,
            storedsize=storedsize,
        )

    # TODO these aren't part of the interface and aren't internal methods.
    # Callers should be fixed to not use them.

    # Used by bundlefilelog, unionfilelog.
    @property
    def indexfile(self):
        return self._revlog.indexfile

    @indexfile.setter
    def indexfile(self, value):
        self._revlog.indexfile = value

    # Used by repo upgrade.
    def clone(self, tr, destrevlog, **kwargs):
        if not isinstance(destrevlog, filelog):
            raise error.ProgrammingError(b'expected filelog to clone()')

        return self._revlog.clone(tr, destrevlog._revlog, **kwargs)


class narrowfilelog(filelog):
    """Filelog variation to be used with narrow stores."""

    def __init__(self, opener, path, narrowmatch):
        super(narrowfilelog, self).__init__(opener, path)
        self._narrowmatch = narrowmatch

    def renamed(self, node):
        res = super(narrowfilelog, self).renamed(node)

        # Renames that come from outside the narrowspec are problematic
        # because we may lack the base text for the rename. This can result
        # in code attempting to walk the ancestry or compute a diff
        # encountering a missing revision. We address this by silently
        # removing rename metadata if the source file is outside the
        # narrow spec.
        #
        # A better solution would be to see if the base revision is available,
        # rather than assuming it isn't.
        #
        # An even better solution would be to teach all consumers of rename
        # metadata that the base revision may not be available.
        #
        # TODO consider better ways of doing this.
        if res and not self._narrowmatch(res[0]):
            return None

        return res

    def size(self, rev):
        # Because we have a custom renamed() that may lie, we need to call
        # the base renamed() to report accurate results.
        node = self.node(rev)
        if super(narrowfilelog, self).renamed(node):
            return len(self.read(node))
        else:
            return super(narrowfilelog, self).size(rev)

    def cmp(self, node, text):
        different = super(narrowfilelog, self).cmp(node, text)

        # Because renamed() may lie, we may get false positives for
        # different content. Check for this by comparing against the original
        # renamed() implementation.
        if different:
            if super(narrowfilelog, self).renamed(node):
                t2 = self.read(node)
                return t2 != text

        return different