view hgext/narrow/narrowdirstate.py @ 38717:aa21a9ad46ea

sparse-revlog: new requirement enabled with format.sparse-revlog

The meaning of the new 'sparse-revlog' requirement is that the revlogs are
allowed to contain wider delta chains with larger holes between the interesting
chunks. These sparse delta chains should be read in several chunks to avoid a
potential explosion of memory usage.

Former version won't know how to read a delta chain in several chunks. They
would keep reading them in a single read, and therefore would be subject to the
potential memory explosion. Hence this new requirement: only versions having
support of sparse-revlog reading should be allowed to read such a revlog.

Implementation of this new algorithm and tools to enable or disable the
requirement will follow in the next changesets.

# narrowdirstate.py - extensions to mercurial dirstate to support narrow clones
#
# Copyright 2017 Google, Inc.
#
# 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 mercurial.i18n import _
from mercurial import (
    error,
    match as matchmod,
    narrowspec,
    util as hgutil,
)

def wrapdirstate(repo, dirstate):
    """Add narrow spec dirstate ignore, block changes outside narrow spec."""

    def _editfunc(fn):
        def _wrapper(self, *args):
            dirstate = repo.dirstate
            narrowmatch = repo.narrowmatch()
            for f in args:
                if f is not None and not narrowmatch(f) and f not in dirstate:
                    raise error.Abort(_("cannot track '%s' - it is outside " +
                        "the narrow clone") % f)
            return fn(self, *args)
        return _wrapper

    def _narrowbackupname(backupname):
        assert 'dirstate' in backupname
        return backupname.replace('dirstate', narrowspec.FILENAME)

    class narrowdirstate(dirstate.__class__):
        def walk(self, match, subrepos, unknown, ignored, full=True,
                 narrowonly=True):
            if narrowonly:
                # hack to not exclude explicitly-specified paths so that they
                # can be warned later on e.g. dirstate.add()
                em = matchmod.exact(match._root, match._cwd, match.files())
                nm = matchmod.unionmatcher([repo.narrowmatch(), em])
                match = matchmod.intersectmatchers(match, nm)
            return super(narrowdirstate, self).walk(match, subrepos, unknown,
                                                    ignored, full)

        # Prevent adding/editing/copying/deleting files that are outside the
        # sparse checkout
        @_editfunc
        def normal(self, *args):
            return super(narrowdirstate, self).normal(*args)

        @_editfunc
        def add(self, *args):
            return super(narrowdirstate, self).add(*args)

        @_editfunc
        def normallookup(self, *args):
            return super(narrowdirstate, self).normallookup(*args)

        @_editfunc
        def copy(self, *args):
            return super(narrowdirstate, self).copy(*args)

        @_editfunc
        def remove(self, *args):
            return super(narrowdirstate, self).remove(*args)

        @_editfunc
        def merge(self, *args):
            return super(narrowdirstate, self).merge(*args)

        def rebuild(self, parent, allfiles, changedfiles=None):
            if changedfiles is None:
                # Rebuilding entire dirstate, let's filter allfiles to match the
                # narrowspec.
                allfiles = [f for f in allfiles if repo.narrowmatch()(f)]
            super(narrowdirstate, self).rebuild(parent, allfiles, changedfiles)

        def restorebackup(self, tr, backupname):
            self._opener.rename(_narrowbackupname(backupname),
                                narrowspec.FILENAME, checkambig=True)
            super(narrowdirstate, self).restorebackup(tr, backupname)

        def savebackup(self, tr, backupname):
            super(narrowdirstate, self).savebackup(tr, backupname)

            narrowbackupname = _narrowbackupname(backupname)
            self._opener.tryunlink(narrowbackupname)
            hgutil.copyfile(self._opener.join(narrowspec.FILENAME),
                            self._opener.join(narrowbackupname), hardlink=True)

        def clearbackup(self, tr, backupname):
            super(narrowdirstate, self).clearbackup(tr, backupname)
            self._opener.unlink(_narrowbackupname(backupname))

    dirstate.__class__ = narrowdirstate
    return dirstate