view hgext/lfs/__init__.py @ 39772:ae531f5e583c

testing: add interface unit tests for file storage

Our strategy for supporting alternate storage backends is to define
interfaces for everything then "code to the interface."

We already have interfaces for various primitives, including file
and manifest storage.

What we don't have is generic unit tests for those interfaces. Up
to this point we've been relying on high-level integration tests
(mainly in the form of existing .t tests) to test alternate storage
backends. And my experience with developing the "simple store" test
extension is that such testing is very tedious: it takes several
minutes to run all tests and when you find a failure, it is often
non-trivial to debug.

This commit starts to change that.

This commit introduces the mercurial.testing.storage module. It
contains testing code for storage. Currently, it defines some
unittest.TestCase classes for testing the file storage interfaces.
It also defines some factory functions that allow a caller to easily
spawn a custom TestCase "bound" to a specific file storage backend
implementation.

A new .py test has been added. It simply defines a callable to produce
filelog and transaction instances on demand and then "registers" the
various test classes so the filelog class can be tested with the
storage interface unit tests.

As part of writing the tests, I identified a couple of apparent
bugs in revlog.py and filelog.py! These are tracked with inline
TODO comments.

Writing the tests makes it more obvious where the storage interface
is lacking. For example, we raise either IndexError or
error.LookupError for missing revisions depending on whether we
use an integer revision or a node. Also, we raise error.RevlogError
in various places when we should be raising a storage-agnostic
error type.

The storage interfaces are currently far from perfect and there is much
work to be done to improve them. But at least with this commit we
finally have the start of unit tests that can be used to "qualify"
the behavior of a storage backend. And when implementing and debugging
new storage backends, we now have an obvious place to define new
tests and have obvious places to insert breakpoints to facilitate
debugging. This should be invaluable when implementing new storage
backends.

I added the mercurial.testing package because these interface
conformance tests are generic and need to be usable by all storage
backends. Having the code live in tests/ would make it difficult for
storage backends implemented in extensions to test their interface
conformance. First, it would require obtaining a copy of Mercurial's
storage test code in order to test. Second, it would make testing
against multiple Mercurial versions difficult, as you would need to
import N copies of the storage testing code in order to achieve test
coverage. By making the test code part of the Mercurial distribution
itself, extensions can `import mercurial.testing.*` to access and run
the test code. The test will run against whatever Mercurial version
is active.

FWIW I've always wanted to move parts of run-tests.py into the
mercurial.* package to make the testing story simpler (e.g. imagine an
`hg debugruntests` command that could invoke the test harness). While I
have no plans to do that in the near future, establishing the
mercurial.testing package does provide a natural home for that code
should someone do this in the future.

Differential Revision: https://phab.mercurial-scm.org/D4650

# 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

from mercurial.i18n import _

from mercurial import (
    bundle2,
    changegroup,
    cmdutil,
    config,
    context,
    error,
    exchange,
    extensions,
    filelog,
    filesetlang,
    hg,
    localrepo,
    minifileset,
    node,
    pycompat,
    registrar,
    revlog,
    scmutil,
    templateutil,
    upgrade,
    util,
    vfs as vfsmod,
    wireprotoserver,
    wireprotov1server,
)

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'

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

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

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

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

templatekeyword = registrar.templatekeyword()
filesetpredicate = registrar.filesetpredicate()

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

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

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):
            repo.svfs.options['lfstrack'] = _trackedmatcher(self)
            return super(lfsrepo, self).commitctx(ctx, error)

    repo.__class__ = lfsrepo

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

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

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

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

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

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

    wrapfunction(exchange, 'push', wrapper.push)
    wrapfunction(wireprotov1server, '_capabilities', wrapper._capabilities)
    wrapfunction(wireprotoserver, 'handlewsgirequest',
                 wireprotolfsserver.handlewsgirequest)

    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)

    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"

    # 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)

@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>')

@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)

@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)