hgext/lfs/__init__.py

commit: improve the files field of changelog for merges

Currently, the files list of merge commits repeats all the deletions
(either actual deletions, or files that got renamed) that happened
between base and p2 of the merge. If p2 is the main branch, the list
can easily be much bigger than the change being merged.

This results in various problems worth improving:
- changelog is bigger than necessary
- `hg log directory` lists many unrelated merge commits, and `hg log
  -v -r commit` frequently fills multiple screens worth of files
- it possibly slows down adjustlinkrev, by forcing it to read more
  manifests, and that function can certainly be a bottleneck
- the server side of pulls can waste a lot of time simply opening the
  filelogs for pointless files (the constant factors for opening even
  a tiny filelog is apparently pretty bad)

So stop listing such files as described in the code.  Impacted merge
commits and their descendants get a different hash than they would
have without this. This doesn't seem problematic, except for
convert. The previous commit helped with that in the hg->hg case (but
if you do svn->hg twice from scratch, hashes can still change).

The rest of the description is numbers. I don't have much to report,
because recreating the files list of existing repositories is not
easy:
- debugupgradeformat and bundle/unbundle don't recreate the list
- export/import tends to choke quickly applying patches or on
  description that contain diffs,
- merge commits from the convert extension don't have the right files
  list for reasons orthogonal to the current commit
- replaying the merge with hg update/hg merge/hg revert --all/hg
  commit can end up failing in hg revert
- I wasn't sure that using debugsetparents + debugrebuilddirstate
  would really build the right thing

I measured commit time before and after this change, in a case with no
files filtered out, several files filtered out (no difference) and 5k
files filtered out (+1% time).

Recreating the 100 more recent merges in a private repo, the
concatenated uncompressed files lists goes from 1.12MB to
0.52MB. Excluding 3 merges that are not representative, then the size
goes from 570k to 15k.
I converted part of mozilla-central, and observed file list shrinking
quite a bit too, starting at the very first merge, 733641d9feaf, going
from 550 files to 10 files (although they have relatively few merges,
so they probably wouldn't care).

Differential Revision: https://phab.mercurial-scm.org/D6613

# 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)

This extension allows large files to be tracked outside of the normal
repository storage and stored on a centralized server, similar to the
``largefiles`` extension.  The ``git-lfs`` protocol is used when
communicating with the server, so existing git infrastructure can be
harnessed.  Even though the files are stored outside of the repository,
they are still integrity checked in the same manner as normal files.

The files stored outside of the repository are downloaded on demand,
which reduces the time to clone, and possibly the local disk usage.
This changes fundamental workflows in a DVCS, so careful thought
should be given before deploying it.  :hg:`convert` can be used to
convert LFS repositories to normal repositories that no longer
require this extension, and do so without changing the commit hashes.
This allows the extension to be disabled if the centralized workflow
becomes burdensome.  However, the pre and post convert clones will
not be able to communicate with each other unless the extension is
enabled on both.

To start a new repository, or to add LFS files to an existing one, just
create an ``.hglfs`` file as described below in the root directory of
the repository.  Typically, this file should be put under version
control, so that the settings will propagate to other repositories with
push and pull.  During any commit, Mercurial will consult this file to
determine if an added or modified file should be stored externally.  The
type of storage depends on the characteristics of the file at each
commit.  A file that is near a size threshold may switch back and forth
between LFS and normal storage, as needed.

Alternately, both normal repositories and largefile controlled
repositories can be converted to LFS by using :hg:`convert` and the
``lfs.track`` config option described below.  The ``.hglfs`` file
should then be created and added, to control subsequent LFS selection.
The hashes are also unchanged in this case.  The LFS and non-LFS
repositories can be distinguished because the LFS repository will
abort any command if this extension is disabled.

Committed LFS files are held locally, until the repository is pushed.
Prior to pushing the normal repository data, the LFS files that are
tracked by the outgoing commits are automatically uploaded to the
configured central server.  No LFS files are transferred on
:hg:`pull` or :hg:`clone`.  Instead, the files are downloaded on
demand as they need to be read, if a cached copy cannot be found
locally.  Both committing and downloading an LFS file will link the
file to a usercache, to speed up future access.  See the `usercache`
config setting described below.

.hglfs::

    The extension reads its configuration from a versioned ``.hglfs``
    configuration file found in the root of the working directory. The
    ``.hglfs`` file uses the same syntax as all other Mercurial
    configuration files. It uses a single section, ``[track]``.

    The ``[track]`` section specifies which files are stored as LFS (or
    not). Each line is keyed by a file pattern, with a predicate value.
    The first file pattern match is used, so put more specific patterns
    first.  The available predicates are ``all()``, ``none()``, and
    ``size()``. See "hg help filesets.size" for the latter.

    Example versioned ``.hglfs`` file::

      [track]
      # No Makefile or python file, anywhere, will be LFS
      **Makefile = none()
      **.py = none()

      **.zip = all()
      **.exe = size(">1MB")

      # Catchall for everything not matched above
      ** = size(">10MB")

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 assume the remote repository also handles blob storage
    # for http(s) URLs.  Otherwise, lfs will prompt to set this when it must
    # use this value.
    # (default: unset)
    url = https://example.com/repo.git/info/lfs

    # Which files to track in LFS.  Path tests are "**.extname" for file
    # extensions, and "path:under/some/directory" for path prefix.  Both
    # are relative to the repository root.
    # File size can be tested with the "size()" fileset, and tests can be
    # joined with fileset operators.  (See "hg help filesets.operators".)
    #
    # Some examples:
    # - all()                       # everything
    # - none()                      # nothing
    # - size(">20MB")               # larger than 20MB
    # - !**.txt                     # anything not a *.txt file
    # - **.zip | **.tar.gz | **.7z  # some types of compressed files
    # - path:bin                    # files under "bin" in the project root
    # - (**.php & size(">2MB")) | (**.js & size(">5MB")) | **.tar.gz
    #     | (path:bin & !path:/bin/README) | size(">1GB")
    # (default: none())
    #
    # This is ignored if there is a tracked '.hglfs' file, and this setting
    # will eventually be deprecated and removed.
    track = size(">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

import sys

from mercurial.i18n import _

from mercurial import (
    config,
    context,
    error,
    exchange,
    extensions,
    exthelper,
    filelog,
    filesetlang,
    localrepo,
    minifileset,
    node,
    pycompat,
    repository,
    revlog,
    scmutil,
    templateutil,
    util,
)

from . import (
    blobstore,
    wireprotolfsserver,
    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'

eh = exthelper.exthelper()
eh.merge(wrapper.eh)
eh.merge(wireprotolfsserver.eh)

cmdtable = eh.cmdtable
configtable = eh.configtable
extsetup = eh.finalextsetup
uisetup = eh.finaluisetup
filesetpredicate = eh.filesetpredicate
reposetup = eh.finalreposetup
templatekeyword = eh.templatekeyword

eh.configitem('experimental', 'lfs.serve',
    default=True,
)
eh.configitem('experimental', 'lfs.user-agent',
    default=None,
)
eh.configitem('experimental', 'lfs.disableusercache',
    default=False,
)
eh.configitem('experimental', 'lfs.worker-enable',
    default=False,
)

eh.configitem('lfs', 'url',
    default=None,
)
eh.configitem('lfs', 'usercache',
    default=None,
)
# Deprecated
eh.configitem('lfs', 'threshold',
    default=None,
)
eh.configitem('lfs', 'track',
    default='none()',
)
eh.configitem('lfs', 'retry',
    default=5,
)

lfsprocessor = (
    wrapper.readfromstore,
    wrapper.writetostore,
    wrapper.bypasscheckhash,
)

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

@eh.uisetup
def _uisetup(ui):
    localrepo.featuresetupfuncs.add(featuresetup)

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

    repo.svfs.lfslocalblobstore = blobstore.local(repo)
    repo.svfs.lfsremoteblobstore = blobstore.remote(repo)

    class lfsrepo(repo.__class__):
        @localrepo.unfilteredmethod
        def commitctx(self, ctx, error=False, origctx=None):
            repo.svfs.options['lfstrack'] = _trackedmatcher(self)
            return super(lfsrepo, self).commitctx(ctx, error, origctx=origctx)

    repo.__class__ = lfsrepo

    if 'lfs' not in repo.requirements:
        def checkrequireslfs(ui, repo, **kwargs):
            if 'lfs' in repo.requirements:
                return 0

            last = kwargs.get(r'node_last')
            _bin = node.bin
            if last:
                s = repo.set('%n:%n', _bin(kwargs[r'node']), _bin(last))
            else:
                s = repo.set('%n', _bin(kwargs[r'node']))
            match = repo._storenarrowmatch
            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 and match(f)):
                    repo.requirements.add('lfs')
                    repo.features.add(repository.REPO_FEATURE_LFS)
                    repo._writerequirements()
                    repo.prepushoutgoinghooks.add('lfs', wrapper.prepush)
                    break

        ui.setconfig('hooks', 'commit.lfs', checkrequireslfs, 'lfs')
        ui.setconfig('hooks', 'pretxnchangegroup.lfs', checkrequireslfs, 'lfs')
    else:
        repo.prepushoutgoinghooks.add('lfs', wrapper.prepush)

def _trackedmatcher(repo):
    """Return a function (path, size) -> bool indicating whether or not to
    track a given file with lfs."""
    if not repo.wvfs.exists('.hglfs'):
        # No '.hglfs' in wdir.  Fallback to config for now.
        trackspec = repo.ui.config('lfs', 'track')

        # deprecated config: lfs.threshold
        threshold = repo.ui.configbytes('lfs', 'threshold')
        if threshold:
            filesetlang.parse(trackspec)  # make sure syntax errors are confined
            trackspec = "(%s) | size('>%d')" % (trackspec, threshold)

        return minifileset.compile(trackspec)

    data = repo.wvfs.tryread('.hglfs')
    if not data:
        return lambda p, s: False

    # Parse errors here will abort with a message that points to the .hglfs file
    # and line number.
    cfg = config.config()
    cfg.parse('.hglfs', data)

    try:
        rules = [(minifileset.compile(pattern), minifileset.compile(rule))
                 for pattern, rule in cfg.items('track')]
    except error.ParseError as e:
        # The original exception gives no indicator that the error is in the
        # .hglfs file, so add that.

        # TODO: See if the line number of the file can be made available.
        raise error.Abort(_('parse error in .hglfs: %s') % e)

    def _match(path, size):
        for pat, rule in rules:
            if pat(path, size):
                return rule(path, size)

        return False

    return _match

# Called by remotefilelog
def wrapfilelog(filelog):
    wrapfunction = extensions.wrapfunction

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

@eh.wrapfunction(localrepo, 'resolverevlogstorevfsoptions')
def _resolverevlogstorevfsoptions(orig, ui, requirements, features):
    opts = orig(ui, requirements, features)
    for name, module in extensions.extensions(ui):
        if module is sys.modules[__name__]:
            if revlog.REVIDX_EXTSTORED in opts[b'flagprocessors']:
                msg = (_(b"cannot register multiple processors on flag '%#x'.")
                       % revlog.REVIDX_EXTSTORED)
                raise error.Abort(msg)

            opts[b'flagprocessors'][revlog.REVIDX_EXTSTORED] = lfsprocessor
            break

    return opts

@eh.extsetup
def _extsetup(ui):
    wrapfilelog(filelog.filelog)

    context.basefilectx.islfs = wrapper.filectxislfs

    scmutil.fileprefetchhooks.add('lfs', wrapper._prefetchfiles)

    # 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.
    exchange._bundlespeccontentopts["v2"]["cg.version"] = "03"

@eh.filesetpredicate('lfs()')
def lfsfileset(mctx, x):
    """File that uses LFS storage."""
    # i18n: "lfs" is a keyword
    filesetlang.getargs(x, 0, 0, _("lfs takes no arguments"))
    ctx = mctx.ctx
    def lfsfilep(f):
        return wrapper.pointerfromctx(ctx, f, removed=True) is not None
    return mctx.predicate(lfsfilep, predrepr='<lfs>')

@eh.templatekeyword('lfs_files', requires={'ctx'})
def lfsfiles(context, mapping):
    """List of strings. All files modified, added, or removed by this
    changeset."""
    ctx = context.resource(mapping, 'ctx')

    pointers = wrapper.pointersfromctx(ctx, removed=True) # {path: pointer}
    files = sorted(pointers.keys())

    def pointer(v):
        # In the file spec, version is first and the other keys are sorted.
        sortkeyfunc = lambda x: (x[0] != 'version', x)
        items = sorted(pointers[v].iteritems(), key=sortkeyfunc)
        return util.sortdict(items)

    makemap = lambda v: {
        'file': v,
        'lfsoid': pointers[v].oid() if pointers[v] else None,
        'lfspointer': templateutil.hybriddict(pointer(v)),
    }

    # TODO: make the separator ', '?
    f = templateutil._showcompatlist(context, mapping, 'lfs_file', files)
    return templateutil.hybrid(f, files, makemap, pycompat.identity)

@eh.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(r'rev', [])
    pointers = wrapper.extractpointers(repo, scmutil.revrange(repo, revs))
    wrapper.uploadblobs(repo, pointers)