view hgext/automv.py @ 35506:fa865878a849

lfs: show a friendly message when pushing lfs to a server without lfs enabled

Upfront disclaimer: I don't know anything about the wire protocol, and this was
pretty much cargo-culted from largefiles, and then clonebundles, since it seems
more modern.  I was surprised that exchange.push() will ensure all of the proper
requirements when exchanging between two local repos, but doesn't care when one
is remote.

All this new capability marker does is inform the client that the extension is
enabled remotely.  It may or may not contain commits with external blobs.

Open issues:

  - largefiles uses 'largefiles=serve' for its capability.  Someday I hope to
    be able to push lfs blobs to an `hg serve` instance.  That will probably
    require a distinct capability.  Should it change to '=serve' then?  Or just
    add an 'lfs-serve' capability then?

  - The flip side of this is more complicated.  It looks like largefiles adds an
    'lheads' command for the client to signal to the server that the extension
    is loaded.  That is then converted to 'heads' and sent through the normal
    wire protocol plumbing.  A client using the 'heads' command directly is
    kicked out with a message indicating that the largefiles extension must be
    loaded.  We could do similar with 'lfsheads', but then a repo with both
    largefiles and lfs blobs can't be pushed over the wire.  Hopefully somebody
    with more wire protocol experience can think of something else.  I see
    'x-hgarg-1' on some commands in the tests, but not on heads, and didn't dig
    any further.

# automv.py
#
# Copyright 2013-2016 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.
"""check for unrecorded moves at commit time (EXPERIMENTAL)

This extension checks at commit/amend time if any of the committed files
comes from an unrecorded mv.

The threshold at which a file is considered a move can be set with the
``automv.similarity`` config option. This option takes a percentage between 0
(disabled) and 100 (files must be identical), the default is 95.

"""

# Using 95 as a default similarity is based on an analysis of the mercurial
# repositories of the cpython, mozilla-central & mercurial repositories, as
# well as 2 very large facebook repositories. At 95 50% of all potential
# missed moves would be caught, as well as correspond with 87% of all
# explicitly marked moves.  Together, 80% of moved files are 95% similar or
# more.
#
# See http://markmail.org/thread/5pxnljesvufvom57 for context.

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    commands,
    copies,
    error,
    extensions,
    pycompat,
    registrar,
    scmutil,
    similar
)

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

configitem('automv', 'similarity',
    default=95,
)

def extsetup(ui):
    entry = extensions.wrapcommand(
        commands.table, 'commit', mvcheck)
    entry[1].append(
        ('', 'no-automv', None,
         _('disable automatic file move detection')))

def mvcheck(orig, ui, repo, *pats, **opts):
    """Hook to check for moves at commit time"""
    opts = pycompat.byteskwargs(opts)
    renames = None
    disabled = opts.pop('no_automv', False)
    if not disabled:
        threshold = ui.configint('automv', 'similarity')
        if not 0 <= threshold <= 100:
            raise error.Abort(_('automv.similarity must be between 0 and 100'))
        if threshold > 0:
            match = scmutil.match(repo[None], pats, opts)
            added, removed = _interestingfiles(repo, match)
            renames = _findrenames(repo, match, added, removed,
                                   threshold / 100.0)

    with repo.wlock():
        if renames is not None:
            scmutil._markchanges(repo, (), (), renames)
        return orig(ui, repo, *pats, **pycompat.strkwargs(opts))

def _interestingfiles(repo, matcher):
    """Find what files were added or removed in this commit.

    Returns a tuple of two lists: (added, removed). Only files not *already*
    marked as moved are included in the added list.

    """
    stat = repo.status(match=matcher)
    added = stat[1]
    removed = stat[2]

    copy = copies._forwardcopies(repo['.'], repo[None], matcher)
    # remove the copy files for which we already have copy info
    added = [f for f in added if f not in copy]

    return added, removed

def _findrenames(repo, matcher, added, removed, similarity):
    """Find what files in added are really moved files.

    Any file named in removed that is at least similarity% similar to a file
    in added is seen as a rename.

    """
    renames = {}
    if similarity > 0:
        for src, dst, score in similar.findrenames(
                repo, added, removed, similarity):
            if repo.ui.verbose:
                repo.ui.status(
                    _('detected move of %s as %s (%d%% similar)\n') % (
                        matcher.rel(src), matcher.rel(dst), score * 100))
            renames[dst] = src
    if renames:
        repo.ui.status(_('detected move of %d files\n') % len(renames))
    return renames