view hgext/automv.py @ 44073:b9e174d4ed11

verify: allow the storage to signal when renames can be tested on `skipread`

This applies the new marker in the lfs handler to show it in action, and adds
the test mentioned at the beginning of the series to show that fulltext isn't
necessary in the LFS case.

The existing `skipread` isn't enough, because it is also set if an error occurs
reading the revlog data, or the data is censored.  It could probably be cleared,
but then it technically violates the interface contract.  That wouldn't matter
for the existing verify algorithm, but it isn't clear how that will change as
alternate storage support is added.

The flag is probably pretty revlog specific, given the comments in verify.py.
But there's already filelog specific stuff in there and I'm not sure what future
storage will bring, so I don't want to over-engineer this.  Likewise, I'm not
sure that we want the verify method for each storage type to completely drive
the bus when it comes to detecting renames, so I don't want to go down the
rabbithole of having verifyintegrity() return metadata hints at this point.

Differential Revision: https://phab.mercurial-scm.org/D7713

# 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(
    b'automv', b'similarity', default=95,
)


def extsetup(ui):
    entry = extensions.wrapcommand(commands.table, b'commit', mvcheck)
    entry[1].append(
        (b'', b'no-automv', None, _(b'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(b'no_automv', False)
    if not disabled:
        threshold = ui.configint(b'automv', b'similarity')
        if not 0 <= threshold <= 100:
            raise error.Abort(_(b'automv.similarity must be between 0 and 100'))
        if threshold > 0:
            match = scmutil.match(repo[None], pats, opts)
            added, removed = _interestingfiles(repo, match)
            uipathfn = scmutil.getuipathfn(repo, legacyrelativevalue=True)
            renames = _findrenames(
                repo, uipathfn, 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.added
    removed = stat.removed

    copy = copies.pathcopies(repo[b'.'], 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, uipathfn, 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(
                    _(b'detected move of %s as %s (%d%% similar)\n')
                    % (uipathfn(src), uipathfn(dst), score * 100)
                )
            renames[dst] = src
    if renames:
        repo.ui.status(_(b'detected move of %d files\n') % len(renames))
    return renames