view hgext/narrow/__init__.py @ 45059:79f6f9fa18c1

documentation: add some internals documentation about bid merge

This is an important algorithm that was only documented on the wiki so far.

Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.

Differential Revision: https://phab.mercurial-scm.org/D8711

# __init__.py - narrowhg extension
#
# 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.
'''create clones which fetch history data for subset of files (EXPERIMENTAL)'''

from __future__ import absolute_import

from mercurial import (
    localrepo,
    registrar,
)

from mercurial.interfaces import repository

from . import (
    narrowbundle2,
    narrowcommands,
    narrowrepo,
    narrowtemplates,
    narrowwirepeer,
)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'

configtable = {}
configitem = registrar.configitem(configtable)
# Narrowhg *has* support for serving ellipsis nodes (which are used at
# least by Google's internal server), but that support is pretty
# fragile and has a lot of problems on real-world repositories that
# have complex graph topologies. This could probably be corrected, but
# absent someone needing the full support for ellipsis nodes in
# repositories with merges, it's unlikely this work will get done. As
# of this writining in late 2017, all repositories large enough for
# ellipsis nodes to be a hard requirement also enforce strictly linear
# history for other scaling reasons.
configitem(
    b'experimental',
    b'narrowservebrokenellipses',
    default=False,
    alias=[(b'narrow', b'serveellipses')],
)

# Export the commands table for Mercurial to see.
cmdtable = narrowcommands.table


def featuresetup(ui, features):
    features.add(repository.NARROW_REQUIREMENT)


def uisetup(ui):
    """Wraps user-facing mercurial commands with narrow-aware versions."""
    localrepo.featuresetupfuncs.add(featuresetup)
    narrowbundle2.setup()
    narrowcommands.setup()
    narrowwirepeer.uisetup()


def reposetup(ui, repo):
    """Wraps local repositories with narrow repo support."""
    if not repo.local():
        return

    repo.ui.setconfig(b'experimental', b'narrow', True, b'narrow-ext')
    if repository.NARROW_REQUIREMENT in repo.requirements:
        narrowrepo.wraprepo(repo)
        narrowwirepeer.reposetup(repo)


templatekeyword = narrowtemplates.templatekeyword
revsetpredicate = narrowtemplates.revsetpredicate