hgext/lfs/__init__.py

fileset: add a lightweight file filtering language

This patch was inspired by one that Jun Wu authored for the fb-experimental
repo, to avoid using matcher for efficiency[1].  We want a way to specify what
files will be converted to LFS at commit time.  And per discussion, we also want
to specify what files to skip, text diff, or merge in another config option.
The current `lfs.threshold` config option could not satisfy complex needs.  I'm
putting it in a core package because Augie floated the idea of also using it for
narrow and sparse.

Yuya suggested farming out to fileset.parse(), which added support for more
symbols.  The only fileset element not supported here is 'negate'.  (List isn't
supported by filesets either.)  I also changed the 'always' token to the 'all()'
predicate for consistency, and introduced 'none()' to improve readability in a
future tracked file based config.  The extension operator was changed from '.'
to '**', to match how recursive path globs are specified.  Finally, I changed
the path matcher from '/' to 'path:' at Yuya's suggestion, for consistency with
matcher.  Unfortunately, ':' is currently reserved in filesets, so this has to
be quoted to be processed as a string instead of a symbol[2].  We should
probably revisit that, because it's seriously ugly.  But it's only used by an
experimental extension, and I think using a file based config for LFS may drive
some more tweaks, so I'm settling for this for now.

I reserved all of the glob characters in fileset except '.' and '_' for the
extension test because those are likely valid extension characters.

Sample filter settings:

  all()                        # everything
  size(">20MB")                # larger than 20MB
  !**.txt                      # except for .txt files
  **.zip | **.tar.gz | **.7z   # some types of compressed files
  "path:bin"                   # files under "bin" in the project root

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-December/109387.html
[2] https://www.mercurial-scm.org/pipermail/mercurial-devel/2018-January/109729.html

# lfs - hash-preserving large file support using Git-LFS protocol
#
# Copyright 2017 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

"""lfs - large file support (EXPERIMENTAL)

Configs::

    [lfs]
    # Remote endpoint. Multiple protocols are supported:
    # - http(s)://user:[e-mail]/path
    #   git-lfs endpoint
    # - file:///tmp/path
    #   local filesystem, usually for testing
    # if unset, lfs will prompt setting this when it must use this value.
    # (default: unset)
    url = https://example.com/lfs

    # size of a file to make it use LFS
    threshold = 10M

    # how many times to retry before giving up on transferring an object
    retry = 5

    # the local directory to store lfs files for sharing across local clones.
    # If not set, the cache is located in an OS specific cache location.
    usercache = /path/to/global/cache
"""

from __future__ import absolute_import

from mercurial.i18n import _

from mercurial import (
    bundle2,
    changegroup,
    context,
    exchange,
    extensions,
    filelog,
    hg,
    localrepo,
    node,
    registrar,
    revlog,
    scmutil,
    upgrade,
    vfs as vfsmod,
    wireproto,
)

from . import (
    blobstore,
    wrapper,
)

# 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 = 'ships-with-hg-core'

configtable = {}
configitem = registrar.configitem(configtable)

configitem('experimental', 'lfs.user-agent',
    default=None,
)

configitem('lfs', 'url',
    default=None,
)
configitem('lfs', 'usercache',
    default=None,
)
configitem('lfs', 'threshold',
    default=None,
)
configitem('lfs', 'retry',
    default=5,
)

cmdtable = {}
command = registrar.command(cmdtable)

templatekeyword = registrar.templatekeyword()

def featuresetup(ui, supported):
    # don't die on seeing a repo with the lfs requirement
    supported |= {'lfs'}

def uisetup(ui):
    localrepo.localrepository.featuresetupfuncs.add(featuresetup)

def reposetup(ui, repo):
    # Nothing to do with a remote repo
    if not repo.local():
        return

    threshold = repo.ui.configbytes('lfs', 'threshold')

    repo.svfs.options['lfsthreshold'] = threshold
    repo.svfs.lfslocalblobstore = blobstore.local(repo)
    repo.svfs.lfsremoteblobstore = blobstore.remote(repo)

    # Push hook
    repo.prepushoutgoinghooks.add('lfs', wrapper.prepush)

    if 'lfs' not in repo.requirements:
        def checkrequireslfs(ui, repo, **kwargs):
            if 'lfs' not in repo.requirements:
                last = kwargs.get('node_last')
                _bin = node.bin
                if last:
                    s = repo.set('%n:%n', _bin(kwargs['node']), _bin(last))
                else:
                    s = repo.set('%n', _bin(kwargs['node']))
            for ctx in s:
                # TODO: is there a way to just walk the files in the commit?
                if any(ctx[f].islfs() for f in ctx.files() if f in ctx):
                    repo.requirements.add('lfs')
                    repo._writerequirements()
                    break

        ui.setconfig('hooks', 'commit.lfs', checkrequireslfs, 'lfs')
        ui.setconfig('hooks', 'pretxnchangegroup.lfs', checkrequireslfs, 'lfs')

def wrapfilelog(filelog):
    wrapfunction = extensions.wrapfunction

    wrapfunction(filelog, 'addrevision', wrapper.filelogaddrevision)
    wrapfunction(filelog, 'renamed', wrapper.filelogrenamed)
    wrapfunction(filelog, 'size', wrapper.filelogsize)

def extsetup(ui):
    wrapfilelog(filelog.filelog)

    wrapfunction = extensions.wrapfunction

    wrapfunction(scmutil, 'wrapconvertsink', wrapper.convertsink)

    wrapfunction(upgrade, '_finishdatamigration',
                 wrapper.upgradefinishdatamigration)

    wrapfunction(upgrade, 'preservedrequirements',
                 wrapper.upgraderequirements)

    wrapfunction(upgrade, 'supporteddestrequirements',
                 wrapper.upgraderequirements)

    wrapfunction(changegroup,
                 'supportedoutgoingversions',
                 wrapper.supportedoutgoingversions)
    wrapfunction(changegroup,
                 'allsupportedversions',
                 wrapper.allsupportedversions)

    wrapfunction(exchange, 'push', wrapper.push)
    wrapfunction(wireproto, '_capabilities', wrapper._capabilities)

    wrapfunction(context.basefilectx, 'cmp', wrapper.filectxcmp)
    wrapfunction(context.basefilectx, 'isbinary', wrapper.filectxisbinary)
    context.basefilectx.islfs = wrapper.filectxislfs

    revlog.addflagprocessor(
        revlog.REVIDX_EXTSTORED,
        (
            wrapper.readfromstore,
            wrapper.writetostore,
            wrapper.bypasscheckhash,
        ),
    )

    wrapfunction(hg, 'clone', wrapper.hgclone)
    wrapfunction(hg, 'postshare', wrapper.hgpostshare)

    # Make bundle choose changegroup3 instead of changegroup2. This affects
    # "hg bundle" command. Note: it does not cover all bundle formats like
    # "packed1". Using "packed1" with lfs will likely cause trouble.
    names = [k for k, v in exchange._bundlespeccgversions.items() if v == '02']
    for k in names:
        exchange._bundlespeccgversions[k] = '03'

    # bundlerepo uses "vfsmod.readonlyvfs(othervfs)", we need to make sure lfs
    # options and blob stores are passed from othervfs to the new readonlyvfs.
    wrapfunction(vfsmod.readonlyvfs, '__init__', wrapper.vfsinit)

    # when writing a bundle via "hg bundle" command, upload related LFS blobs
    wrapfunction(bundle2, 'writenewbundle', wrapper.writenewbundle)

@templatekeyword('lfs_files')
def lfsfiles(repo, ctx, **args):
    """List of strings. LFS files added or modified by the changeset."""
    pointers = wrapper.pointersfromctx(ctx) # {path: pointer}
    return sorted(pointers.keys())

@command('debuglfsupload',
         [('r', 'rev', [], _('upload large files introduced by REV'))])
def debuglfsupload(ui, repo, **opts):
    """upload lfs blobs added by the working copy parent or given revisions"""
    revs = opts.get('rev', [])
    pointers = wrapper.extractpointers(repo, scmutil.revrange(repo, revs))
    wrapper.uploadblobs(repo, pointers)