view hgext/narrow/narrowbundle2.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

# narrowbundle2.py - bundle2 extensions for narrow repository support
#
# Copyright 2017 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno
import struct

from mercurial.i18n import _
from mercurial.node import (
    bin,
    nullid,
)
from mercurial import (
    bundle2,
    changegroup,
    error,
    exchange,
    extensions,
    match as matchmod,
    narrowspec,
    repair,
    repository,
    util,
    wireprototypes,
)
from mercurial.utils import (
    stringutil,
)

NARROWCAP = 'narrow'
_NARROWACL_SECTION = 'narrowhgacl'
_CHANGESPECPART = NARROWCAP + ':changespec'
_SPECPART = NARROWCAP + ':spec'
_SPECPART_INCLUDE = 'include'
_SPECPART_EXCLUDE = 'exclude'
_KILLNODESIGNAL = 'KILL'
_DONESIGNAL = 'DONE'
_ELIDEDCSHEADER = '>20s20s20sl' # cset id, p1, p2, len(text)
_ELIDEDMFHEADER = '>20s20s20s20sl' # manifest id, p1, p2, link id, len(text)
_CSHEADERSIZE = struct.calcsize(_ELIDEDCSHEADER)
_MFHEADERSIZE = struct.calcsize(_ELIDEDMFHEADER)

# When advertising capabilities, always include narrow clone support.
def getrepocaps_narrow(orig, repo, **kwargs):
    caps = orig(repo, **kwargs)
    caps[NARROWCAP] = ['v0']
    return caps

def getbundlechangegrouppart_widen(bundler, repo, source, bundlecaps=None,
                                   b2caps=None, heads=None, common=None,
                                   **kwargs):
    """Handling changegroup changegroup generation on the server when user
    is widening their narrowspec"""

    cgversions = b2caps.get('changegroup')
    if cgversions:  # 3.1 and 3.2 ship with an empty value
        cgversions = [v for v in cgversions
                      if v in changegroup.supportedoutgoingversions(repo)]
        if not cgversions:
            raise ValueError(_('no common changegroup version'))
        version = max(cgversions)
    else:
        raise ValueError(_("server does not advertise changegroup version,"
                           " can't negotiate support for ellipsis nodes"))

    include = sorted(filter(bool, kwargs.get(r'includepats', [])))
    exclude = sorted(filter(bool, kwargs.get(r'excludepats', [])))
    newmatch = narrowspec.match(repo.root, include=include, exclude=exclude)
    oldinclude = sorted(filter(bool, kwargs.get(r'oldincludepats', [])))
    oldexclude = sorted(filter(bool, kwargs.get(r'oldexcludepats', [])))
    oldmatch = narrowspec.match(repo.root, include=oldinclude,
                                exclude=oldexclude)
    diffmatch = matchmod.differencematcher(newmatch, oldmatch)
    common = set(common or [nullid])

    if (oldinclude != include or oldexclude != exclude):
        common = repo.revs("::%ln", common)
        commonnodes = set()
        cl = repo.changelog
        for c in common:
            commonnodes.add(cl.node(c))
        if commonnodes:
            # XXX: we should only send the filelogs (and treemanifest). user
            # already has the changelog and manifest
            packer = changegroup.getbundler(version, repo,
                                            filematcher=diffmatch,
                                            fullnodes=commonnodes)
            cgdata = packer.generate(set([nullid]), list(commonnodes), False,
                                     source, changelog=False)

            part = bundler.newpart('changegroup', data=cgdata)
            part.addparam('version', version)
            if 'treemanifest' in repo.requirements:
                part.addparam('treemanifest', '1')

# Serve a changegroup for a client with a narrow clone.
def getbundlechangegrouppart_narrow(bundler, repo, source,
                                    bundlecaps=None, b2caps=None, heads=None,
                                    common=None, **kwargs):
    assert repo.ui.configbool('experimental', 'narrowservebrokenellipses')

    cgversions = b2caps.get('changegroup')
    if cgversions:  # 3.1 and 3.2 ship with an empty value
        cgversions = [v for v in cgversions
                      if v in changegroup.supportedoutgoingversions(repo)]
        if not cgversions:
            raise ValueError(_('no common changegroup version'))
        version = max(cgversions)
    else:
        raise ValueError(_("server does not advertise changegroup version,"
                           " can't negotiate support for ellipsis nodes"))

    include = sorted(filter(bool, kwargs.get(r'includepats', [])))
    exclude = sorted(filter(bool, kwargs.get(r'excludepats', [])))
    newmatch = narrowspec.match(repo.root, include=include, exclude=exclude)

    depth = kwargs.get(r'depth', None)
    if depth is not None:
        depth = int(depth)
        if depth < 1:
            raise error.Abort(_('depth must be positive, got %d') % depth)

    heads = set(heads or repo.heads())
    common = set(common or [nullid])
    oldinclude = sorted(filter(bool, kwargs.get(r'oldincludepats', [])))
    oldexclude = sorted(filter(bool, kwargs.get(r'oldexcludepats', [])))
    known = {bin(n) for n in kwargs.get(r'known', [])}
    if known and (oldinclude != include or oldexclude != exclude):
        # Steps:
        # 1. Send kill for "$known & ::common"
        #
        # 2. Send changegroup for ::common
        #
        # 3. Proceed.
        #
        # In the future, we can send kills for only the specific
        # nodes we know should go away or change shape, and then
        # send a data stream that tells the client something like this:
        #
        # a) apply this changegroup
        # b) apply nodes XXX, YYY, ZZZ that you already have
        # c) goto a
        #
        # until they've built up the full new state.
        # Convert to revnums and intersect with "common". The client should
        # have made it a subset of "common" already, but let's be safe.
        known = set(repo.revs("%ln & ::%ln", known, common))
        # TODO: we could send only roots() of this set, and the
        # list of nodes in common, and the client could work out
        # what to strip, instead of us explicitly sending every
        # single node.
        deadrevs = known
        def genkills():
            for r in deadrevs:
                yield _KILLNODESIGNAL
                yield repo.changelog.node(r)
            yield _DONESIGNAL
        bundler.newpart(_CHANGESPECPART, data=genkills())
        newvisit, newfull, newellipsis = exchange._computeellipsis(
            repo, set(), common, known, newmatch)
        if newvisit:
            packer = changegroup.getbundler(version, repo,
                                            filematcher=newmatch,
                                            ellipses=True,
                                            shallow=depth is not None,
                                            ellipsisroots=newellipsis,
                                            fullnodes=newfull)
            cgdata = packer.generate(common, newvisit, False, source)

            part = bundler.newpart('changegroup', data=cgdata)
            part.addparam('version', version)
            if 'treemanifest' in repo.requirements:
                part.addparam('treemanifest', '1')

    visitnodes, relevant_nodes, ellipsisroots = exchange._computeellipsis(
        repo, common, heads, set(), newmatch, depth=depth)

    repo.ui.debug('Found %d relevant revs\n' % len(relevant_nodes))
    if visitnodes:
        packer = changegroup.getbundler(version, repo,
                                        filematcher=newmatch,
                                        ellipses=True,
                                        shallow=depth is not None,
                                        ellipsisroots=ellipsisroots,
                                        fullnodes=relevant_nodes)
        cgdata = packer.generate(common, visitnodes, False, source)

        part = bundler.newpart('changegroup', data=cgdata)
        part.addparam('version', version)
        if 'treemanifest' in repo.requirements:
            part.addparam('treemanifest', '1')

@bundle2.parthandler(_SPECPART, (_SPECPART_INCLUDE, _SPECPART_EXCLUDE))
def _handlechangespec_2(op, inpart):
    includepats = set(inpart.params.get(_SPECPART_INCLUDE, '').splitlines())
    excludepats = set(inpart.params.get(_SPECPART_EXCLUDE, '').splitlines())
    narrowspec.validatepatterns(includepats)
    narrowspec.validatepatterns(excludepats)

    if not repository.NARROW_REQUIREMENT in op.repo.requirements:
        op.repo.requirements.add(repository.NARROW_REQUIREMENT)
        op.repo._writerequirements()
    op.repo.setnarrowpats(includepats, excludepats)

@bundle2.parthandler(_CHANGESPECPART)
def _handlechangespec(op, inpart):
    repo = op.repo
    cl = repo.changelog

    # changesets which need to be stripped entirely. either they're no longer
    # needed in the new narrow spec, or the server is sending a replacement
    # in the changegroup part.
    clkills = set()

    # A changespec part contains all the updates to ellipsis nodes
    # that will happen as a result of widening or narrowing a
    # repo. All the changes that this block encounters are ellipsis
    # nodes or flags to kill an existing ellipsis.
    chunksignal = changegroup.readexactly(inpart, 4)
    while chunksignal != _DONESIGNAL:
        if chunksignal == _KILLNODESIGNAL:
            # a node used to be an ellipsis but isn't anymore
            ck = changegroup.readexactly(inpart, 20)
            if cl.hasnode(ck):
                clkills.add(ck)
        else:
            raise error.Abort(
                _('unexpected changespec node chunk type: %s') % chunksignal)
        chunksignal = changegroup.readexactly(inpart, 4)

    if clkills:
        # preserve bookmarks that repair.strip() would otherwise strip
        bmstore = repo._bookmarks
        class dummybmstore(dict):
            def applychanges(self, repo, tr, changes):
                pass
            def recordchange(self, tr): # legacy version
                pass
        repo._bookmarks = dummybmstore()
        chgrpfile = repair.strip(op.ui, repo, list(clkills), backup=True,
                                 topic='widen')
        repo._bookmarks = bmstore
        if chgrpfile:
            op._widen_uninterr = repo.ui.uninterruptable()
            op._widen_uninterr.__enter__()
            # presence of _widen_bundle attribute activates widen handler later
            op._widen_bundle = chgrpfile
    # Set the new narrowspec if we're widening. The setnewnarrowpats() method
    # will currently always be there when using the core+narrowhg server, but
    # other servers may include a changespec part even when not widening (e.g.
    # because we're deepening a shallow repo).
    if util.safehasattr(repo, 'setnewnarrowpats'):
        repo.setnewnarrowpats()

def handlechangegroup_widen(op, inpart):
    """Changegroup exchange handler which restores temporarily-stripped nodes"""
    # We saved a bundle with stripped node data we must now restore.
    # This approach is based on mercurial/repair.py@6ee26a53c111.
    repo = op.repo
    ui = op.ui

    chgrpfile = op._widen_bundle
    del op._widen_bundle
    vfs = repo.vfs

    ui.note(_("adding branch\n"))
    f = vfs.open(chgrpfile, "rb")
    try:
        gen = exchange.readbundle(ui, f, chgrpfile, vfs)
        if not ui.verbose:
            # silence internal shuffling chatter
            ui.pushbuffer()
        if isinstance(gen, bundle2.unbundle20):
            with repo.transaction('strip') as tr:
                bundle2.processbundle(repo, gen, lambda: tr)
        else:
            gen.apply(repo, 'strip', 'bundle:' + vfs.join(chgrpfile), True)
        if not ui.verbose:
            ui.popbuffer()
    finally:
        f.close()

    # remove undo files
    for undovfs, undofile in repo.undofiles():
        try:
            undovfs.unlink(undofile)
        except OSError as e:
            if e.errno != errno.ENOENT:
                ui.warn(_('error removing %s: %s\n') %
                        (undovfs.join(undofile), stringutil.forcebytestr(e)))

    # Remove partial backup only if there were no exceptions
    op._widen_uninterr.__exit__(None, None, None)
    vfs.unlink(chgrpfile)

def setup():
    """Enable narrow repo support in bundle2-related extension points."""
    extensions.wrapfunction(bundle2, 'getrepocaps', getrepocaps_narrow)

    getbundleargs = wireprototypes.GETBUNDLE_ARGUMENTS

    getbundleargs['narrow'] = 'boolean'
    getbundleargs['widen'] = 'boolean'
    getbundleargs['depth'] = 'plain'
    getbundleargs['oldincludepats'] = 'csv'
    getbundleargs['oldexcludepats'] = 'csv'
    getbundleargs['includepats'] = 'csv'
    getbundleargs['excludepats'] = 'csv'
    getbundleargs['known'] = 'csv'

    # Extend changegroup serving to handle requests from narrow clients.
    origcgfn = exchange.getbundle2partsmapping['changegroup']
    def wrappedcgfn(*args, **kwargs):
        repo = args[1]
        if repo.ui.has_section(_NARROWACL_SECTION):
            kwargs = exchange.applynarrowacl(repo, kwargs)

        if (kwargs.get(r'narrow', False) and
            repo.ui.configbool('experimental', 'narrowservebrokenellipses')):
            getbundlechangegrouppart_narrow(*args, **kwargs)
        elif kwargs.get(r'widen', False) and kwargs.get(r'narrow', False):
            getbundlechangegrouppart_widen(*args, **kwargs)
        else:
            origcgfn(*args, **kwargs)
    exchange.getbundle2partsmapping['changegroup'] = wrappedcgfn

    # Extend changegroup receiver so client can fixup after widen requests.
    origcghandler = bundle2.parthandlermapping['changegroup']
    def wrappedcghandler(op, inpart):
        origcghandler(op, inpart)
        if util.safehasattr(op, '_widen_bundle'):
            handlechangegroup_widen(op, inpart)
    wrappedcghandler.params = origcghandler.params
    bundle2.parthandlermapping['changegroup'] = wrappedcghandler