view hgext/narrow/narrowrepo.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.

# narrowrepo.py - repository which supports narrow revlogs, lazy loading
#
# 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 import (
    changegroup,
    hg,
    narrowspec,
    scmutil,
)

from . import (
    narrowdirstate,
    narrowrevlog,
)

def wrappostshare(orig, sourcerepo, destrepo, **kwargs):
    orig(sourcerepo, destrepo, **kwargs)
    if changegroup.NARROW_REQUIREMENT in sourcerepo.requirements:
        with destrepo.wlock():
            with destrepo.vfs('shared', 'a') as fp:
                fp.write(narrowspec.FILENAME + '\n')

def unsharenarrowspec(orig, ui, repo, repopath):
    if (changegroup.NARROW_REQUIREMENT in repo.requirements
        and repo.path == repopath and repo.shared()):
        srcrepo = hg.sharedreposource(repo)
        with srcrepo.vfs(narrowspec.FILENAME) as f:
            spec = f.read()
        with repo.vfs(narrowspec.FILENAME, 'w') as f:
            f.write(spec)
    return orig(ui, repo, repopath)

def wraprepo(repo):
    """Enables narrow clone functionality on a single local repository."""

    class narrowrepository(repo.__class__):

        def file(self, f):
            fl = super(narrowrepository, self).file(f)
            narrowrevlog.makenarrowfilelog(fl, self.narrowmatch())
            return fl

        # I'm not sure this is the right place to do this filter.
        # context._manifestmatches() would probably be better, or perhaps
        # move it to a later place, in case some of the callers do want to know
        # which directories changed. This seems to work for now, though.
        def status(self, *args, **kwargs):
            s = super(narrowrepository, self).status(*args, **kwargs)
            narrowmatch = self.narrowmatch()
            modified = list(filter(narrowmatch, s.modified))
            added = list(filter(narrowmatch, s.added))
            removed = list(filter(narrowmatch, s.removed))
            deleted = list(filter(narrowmatch, s.deleted))
            unknown = list(filter(narrowmatch, s.unknown))
            ignored = list(filter(narrowmatch, s.ignored))
            clean = list(filter(narrowmatch, s.clean))
            return scmutil.status(modified, added, removed, deleted, unknown,
                                  ignored, clean)

        def _makedirstate(self):
            dirstate = super(narrowrepository, self)._makedirstate()
            return narrowdirstate.wrapdirstate(self, dirstate)

    repo.__class__ = narrowrepository