annotate tests/simplestorerepo.py @ 40393:229d23cdb203

exchangev2: support fetching shallow files history

This commit teaches the exchangev2 client code to handle fetching shallow
files data.

Only shallow fetching of files data is supported: shallow fetching of
changeset and manifest data is explicitly not yet supported.

Previously, we would fetch file revisions for changesets that were received
by the current pull operation. In the new model, we calculate the set of
"relevant" changesets given the pull depth and only fetch files data for
those changesets.

We also teach the "filesdata" command invocation to vary parameters as needed.

The implementation here is far from complete or optimal. Subsequent pulls will
end up re-fetching a lot of files data. But the application of this data should
mostly be a no-op on the client, so it isn't a big deal.

Depending on the order file revisions are fetched in, revisions could get
inserted with the wrong revision number relationships. I think the best way
to deal with this is to remove revision numbers from storage and to either
dynamically derive them (by reconstructing a DAG from nodes/parents) or remove
revision numbers from the file storage interface completely.

A missing API that we'll likely want to write pretty soon is "ensure files
for revision(s) are present." We can kind of cajole exchangev2.pull() to do
this. But it isn't very efficient. For example, in simple cases like
widening the store to obtain data for a single revision, it is probably
more efficient to walk the manifest and find exactly which file revisions
are missing and to make explicit requests for just their data. In more
advanced cases, asking the server for all files data may be more efficient,
even though it requires sending data the client already has. There is tons
of room for future experimentation here. And TBH I'm not sure what the
final state will be.

Anyway, this commit gets us pretty close to being able to have shallow
and narrow checkouts with exchangev2/sqlite storage. Close enough that a
minimal extension should be able to provide fill in the gaps until the code
in core stabilizes and there is a user-facing way to trigger the
narrow/shallow bits from `hg clone` without also implying using of the
narrow extension...

Differential Revision: https://phab.mercurial-scm.org/D5169

# simplestorerepo.py - Extension that swaps in alternate repository storage.
#
# Copyright 2018 Gregory Szorc <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

# To use this with the test suite:
#
#   $ HGREPOFEATURES="simplestore" ./run-tests.py \
#       --extra-config-opt extensions.simplestore=`pwd`/simplestorerepo.py

from __future__ import absolute_import

import stat

from mercurial.i18n import _
from mercurial.node import (
    bin,
    hex,
    nullid,
    nullrev,
)
from mercurial.thirdparty import (
    attr,
    cbor,
)
from mercurial import (
    ancestor,
    bundlerepo,
    error,
    extensions,
    localrepo,
    mdiff,
    pycompat,
    repository,
    revlog,
    store,
    verify,
)
from mercurial.utils import (
    interfaceutil,
    storageutil,
)

# 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'

REQUIREMENT = 'testonly-simplestore'

def validatenode(node):
    if isinstance(node, int):
        raise ValueError('expected node; got int')

    if len(node) != 20:
        raise ValueError('expected 20 byte node')

def validaterev(rev):
    if not isinstance(rev, int):
        raise ValueError('expected int')

class simplestoreerror(error.StorageError):
    pass

@interfaceutil.implementer(repository.irevisiondelta)
@attr.s(slots=True, frozen=True)
class simplestorerevisiondelta(object):
    node = attr.ib()
    p1node = attr.ib()
    p2node = attr.ib()
    basenode = attr.ib()
    linknode = attr.ib()
    flags = attr.ib()
    baserevisionsize = attr.ib()
    revision = attr.ib()
    delta = attr.ib()

@interfaceutil.implementer(repository.ifilestorage)
class filestorage(object):
    """Implements storage for a tracked path.

    Data is stored in the VFS in a directory corresponding to the tracked
    path.

    Index data is stored in an ``index`` file using CBOR.

    Fulltext data is stored in files having names of the node.
    """

    def __init__(self, svfs, path):
        self._svfs = svfs
        self._path = path

        self._storepath = b'/'.join([b'data', path])
        self._indexpath = b'/'.join([self._storepath, b'index'])

        indexdata = self._svfs.tryread(self._indexpath)
        if indexdata:
            indexdata = cbor.loads(indexdata)

        self._indexdata = indexdata or []
        self._indexbynode = {}
        self._indexbyrev = {}
        self._index = []
        self._refreshindex()

    def _refreshindex(self):
        self._indexbynode.clear()
        self._indexbyrev.clear()
        self._index = []

        for i, entry in enumerate(self._indexdata):
            self._indexbynode[entry[b'node']] = entry
            self._indexbyrev[i] = entry

        self._indexbynode[nullid] = {
            b'node': nullid,
            b'p1': nullid,
            b'p2': nullid,
            b'linkrev': nullrev,
            b'flags': 0,
        }

        self._indexbyrev[nullrev] = {
            b'node': nullid,
            b'p1': nullid,
            b'p2': nullid,
            b'linkrev': nullrev,
            b'flags': 0,
        }

        for i, entry in enumerate(self._indexdata):
            p1rev, p2rev = self.parentrevs(self.rev(entry[b'node']))

            # start, length, rawsize, chainbase, linkrev, p1, p2, node
            self._index.append((0, 0, 0, -1, entry[b'linkrev'], p1rev, p2rev,
                                entry[b'node']))

        self._index.append((0, 0, 0, -1, -1, -1, -1, nullid))

    def __len__(self):
        return len(self._indexdata)

    def __iter__(self):
        return iter(range(len(self)))

    def revs(self, start=0, stop=None):
        step = 1
        if stop is not None:
            if start > stop:
                step = -1

            stop += step
        else:
            stop = len(self)

        return range(start, stop, step)

    def parents(self, node):
        validatenode(node)

        if node not in self._indexbynode:
            raise KeyError('unknown node')

        entry = self._indexbynode[node]

        return entry[b'p1'], entry[b'p2']

    def parentrevs(self, rev):
        p1, p2 = self.parents(self._indexbyrev[rev][b'node'])
        return self.rev(p1), self.rev(p2)

    def rev(self, node):
        validatenode(node)

        try:
            self._indexbynode[node]
        except KeyError:
            raise error.LookupError(node, self._indexpath, _('no node'))

        for rev, entry in self._indexbyrev.items():
            if entry[b'node'] == node:
                return rev

        raise error.ProgrammingError('this should not occur')

    def node(self, rev):
        validaterev(rev)

        return self._indexbyrev[rev][b'node']

    def lookup(self, node):
        if isinstance(node, int):
            return self.node(node)

        if len(node) == 20:
            self.rev(node)
            return node

        try:
            rev = int(node)
            if '%d' % rev != node:
                raise ValueError

            if rev < 0:
                rev = len(self) + rev
            if rev < 0 or rev >= len(self):
                raise ValueError

            return self.node(rev)
        except (ValueError, OverflowError):
            pass

        if len(node) == 40:
            try:
                rawnode = bin(node)
                self.rev(rawnode)
                return rawnode
            except TypeError:
                pass

        raise error.LookupError(node, self._path, _('invalid lookup input'))

    def linkrev(self, rev):
        validaterev(rev)

        return self._indexbyrev[rev][b'linkrev']

    def _flags(self, rev):
        validaterev(rev)

        return self._indexbyrev[rev][b'flags']

    def _candelta(self, baserev, rev):
        validaterev(baserev)
        validaterev(rev)

        if ((self._flags(baserev) & revlog.REVIDX_RAWTEXT_CHANGING_FLAGS)
            or (self._flags(rev) & revlog.REVIDX_RAWTEXT_CHANGING_FLAGS)):
            return False

        return True

    def _processflags(self, text, flags, operation, raw=False):
        if flags == 0:
            return text, True

        if flags & ~revlog.REVIDX_KNOWN_FLAGS:
            raise simplestoreerror(_("incompatible revision flag '%#x'") %
                                   (flags & ~revlog.REVIDX_KNOWN_FLAGS))

        validatehash = True
        # Depending on the operation (read or write), the order might be
        # reversed due to non-commutative transforms.
        orderedflags = revlog.REVIDX_FLAGS_ORDER
        if operation == 'write':
            orderedflags = reversed(orderedflags)

        for flag in orderedflags:
            # If a flagprocessor has been registered for a known flag, apply the
            # related operation transform and update result tuple.
            if flag & flags:
                vhash = True

                if flag not in revlog._flagprocessors:
                    message = _("missing processor for flag '%#x'") % (flag)
                    raise simplestoreerror(message)

                processor = revlog._flagprocessors[flag]
                if processor is not None:
                    readtransform, writetransform, rawtransform = processor

                    if raw:
                        vhash = rawtransform(self, text)
                    elif operation == 'read':
                        text, vhash = readtransform(self, text)
                    else:  # write operation
                        text, vhash = writetransform(self, text)
                validatehash = validatehash and vhash

        return text, validatehash

    def checkhash(self, text, node, p1=None, p2=None, rev=None):
        if p1 is None and p2 is None:
            p1, p2 = self.parents(node)
        if node != storageutil.hashrevisionsha1(text, p1, p2):
            raise simplestoreerror(_("integrity check failed on %s") %
                self._path)

    def revision(self, node, raw=False):
        validatenode(node)

        if node == nullid:
            return b''

        rev = self.rev(node)
        flags = self._flags(rev)

        path = b'/'.join([self._storepath, hex(node)])
        rawtext = self._svfs.read(path)

        text, validatehash = self._processflags(rawtext, flags, 'read', raw=raw)
        if validatehash:
            self.checkhash(text, node, rev=rev)

        return text

    def read(self, node):
        validatenode(node)

        revision = self.revision(node)

        if not revision.startswith(b'\1\n'):
            return revision

        start = revision.index(b'\1\n', 2)
        return revision[start + 2:]

    def renamed(self, node):
        validatenode(node)

        if self.parents(node)[0] != nullid:
            return False

        fulltext = self.revision(node)
        m = storageutil.parsemeta(fulltext)[0]

        if m and 'copy' in m:
            return m['copy'], bin(m['copyrev'])

        return False

    def cmp(self, node, text):
        validatenode(node)

        t = text

        if text.startswith(b'\1\n'):
            t = b'\1\n\1\n' + text

        p1, p2 = self.parents(node)

        if storageutil.hashrevisionsha1(t, p1, p2) == node:
            return False

        if self.iscensored(self.rev(node)):
            return text != b''

        if self.renamed(node):
            t2 = self.read(node)
            return t2 != text

        return True

    def size(self, rev):
        validaterev(rev)

        node = self._indexbyrev[rev][b'node']

        if self.renamed(node):
            return len(self.read(node))

        if self.iscensored(rev):
            return 0

        return len(self.revision(node))

    def iscensored(self, rev):
        validaterev(rev)

        return self._flags(rev) & repository.REVISION_FLAG_CENSORED

    def commonancestorsheads(self, a, b):
        validatenode(a)
        validatenode(b)

        a = self.rev(a)
        b = self.rev(b)

        ancestors = ancestor.commonancestorsheads(self.parentrevs, a, b)
        return pycompat.maplist(self.node, ancestors)

    def descendants(self, revs):
        # This is a copy of revlog.descendants()
        first = min(revs)
        if first == nullrev:
            for i in self:
                yield i
            return

        seen = set(revs)
        for i in self.revs(start=first + 1):
            for x in self.parentrevs(i):
                if x != nullrev and x in seen:
                    seen.add(i)
                    yield i
                    break

    # Required by verify.
    def files(self):
        entries = self._svfs.listdir(self._storepath)

        # Strip out undo.backup.* files created as part of transaction
        # recording.
        entries = [f for f in entries if not f.startswith('undo.backup.')]

        return [b'/'.join((self._storepath, f)) for f in entries]

    def add(self, text, meta, transaction, linkrev, p1, p2):
        if meta or text.startswith(b'\1\n'):
            text = storageutil.packmeta(meta, text)

        return self.addrevision(text, transaction, linkrev, p1, p2)

    def addrevision(self, text, transaction, linkrev, p1, p2, node=None,
                    flags=revlog.REVIDX_DEFAULT_FLAGS, cachedelta=None):
        validatenode(p1)
        validatenode(p2)

        if flags:
            node = node or storageutil.hashrevisionsha1(text, p1, p2)

        rawtext, validatehash = self._processflags(text, flags, 'write')

        node = node or storageutil.hashrevisionsha1(text, p1, p2)

        if node in self._indexbynode:
            return node

        if validatehash:
            self.checkhash(rawtext, node, p1=p1, p2=p2)

        return self._addrawrevision(node, rawtext, transaction, linkrev, p1, p2,
                                    flags)

    def _addrawrevision(self, node, rawtext, transaction, link, p1, p2, flags):
        transaction.addbackup(self._indexpath)

        path = b'/'.join([self._storepath, hex(node)])

        self._svfs.write(path, rawtext)

        self._indexdata.append({
            b'node': node,
            b'p1': p1,
            b'p2': p2,
            b'linkrev': link,
            b'flags': flags,
        })

        self._reflectindexupdate()

        return node

    def _reflectindexupdate(self):
        self._refreshindex()
        self._svfs.write(self._indexpath, cbor.dumps(self._indexdata))

    def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None,
                 maybemissingparents=False):
        if maybemissingparents:
            raise error.Abort(_('simple store does not support missing parents '
                                'write mode'))

        nodes = []

        transaction.addbackup(self._indexpath)

        for node, p1, p2, linknode, deltabase, delta, flags in deltas:
            linkrev = linkmapper(linknode)
            flags = flags or revlog.REVIDX_DEFAULT_FLAGS

            nodes.append(node)

            if node in self._indexbynode:
                continue

            # Need to resolve the fulltext from the delta base.
            if deltabase == nullid:
                text = mdiff.patch(b'', delta)
            else:
                text = mdiff.patch(self.revision(deltabase), delta)

            self._addrawrevision(node, text, transaction, linkrev, p1, p2,
                                 flags)

            if addrevisioncb:
                addrevisioncb(self, node)

        return nodes

    def heads(self, start=None, stop=None):
        # This is copied from revlog.py.
        if start is None and stop is None:
            if not len(self):
                return [nullid]
            return [self.node(r) for r in self.headrevs()]

        if start is None:
            start = nullid
        if stop is None:
            stop = []
        stoprevs = set([self.rev(n) for n in stop])
        startrev = self.rev(start)
        reachable = {startrev}
        heads = {startrev}

        parentrevs = self.parentrevs
        for r in self.revs(start=startrev + 1):
            for p in parentrevs(r):
                if p in reachable:
                    if r not in stoprevs:
                        reachable.add(r)
                    heads.add(r)
                if p in heads and p not in stoprevs:
                    heads.remove(p)

        return [self.node(r) for r in heads]

    def children(self, node):
        validatenode(node)

        # This is a copy of revlog.children().
        c = []
        p = self.rev(node)
        for r in self.revs(start=p + 1):
            prevs = [pr for pr in self.parentrevs(r) if pr != nullrev]
            if prevs:
                for pr in prevs:
                    if pr == p:
                        c.append(self.node(r))
            elif p == nullrev:
                c.append(self.node(r))
        return c

    def getstrippoint(self, minlink):

        # This is largely a copy of revlog.getstrippoint().
        brokenrevs = set()
        strippoint = len(self)

        heads = {}
        futurelargelinkrevs = set()
        for head in self.heads():
            headlinkrev = self.linkrev(self.rev(head))
            heads[head] = headlinkrev
            if headlinkrev >= minlink:
                futurelargelinkrevs.add(headlinkrev)

        # This algorithm involves walking down the rev graph, starting at the
        # heads. Since the revs are topologically sorted according to linkrev,
        # once all head linkrevs are below the minlink, we know there are
        # no more revs that could have a linkrev greater than minlink.
        # So we can stop walking.
        while futurelargelinkrevs:
            strippoint -= 1
            linkrev = heads.pop(strippoint)

            if linkrev < minlink:
                brokenrevs.add(strippoint)
            else:
                futurelargelinkrevs.remove(linkrev)

            for p in self.parentrevs(strippoint):
                if p != nullrev:
                    plinkrev = self.linkrev(p)
                    heads[p] = plinkrev
                    if plinkrev >= minlink:
                        futurelargelinkrevs.add(plinkrev)

        return strippoint, brokenrevs

    def strip(self, minlink, transaction):
        if not len(self):
            return

        rev, _ignored = self.getstrippoint(minlink)
        if rev == len(self):
            return

        # Purge index data starting at the requested revision.
        self._indexdata[rev:] = []
        self._reflectindexupdate()

def issimplestorefile(f, kind, st):
    if kind != stat.S_IFREG:
        return False

    if store.isrevlog(f, kind, st):
        return False

    # Ignore transaction undo files.
    if f.startswith('undo.'):
        return False

    # Otherwise assume it belongs to the simple store.
    return True

class simplestore(store.encodedstore):
    def datafiles(self):
        for x in super(simplestore, self).datafiles():
            yield x

        # Supplement with non-revlog files.
        extrafiles = self._walk('data', True, filefilter=issimplestorefile)

        for unencoded, encoded, size in extrafiles:
            try:
                unencoded = store.decodefilename(unencoded)
            except KeyError:
                unencoded = None

            yield unencoded, encoded, size

def reposetup(ui, repo):
    if not repo.local():
        return

    if isinstance(repo, bundlerepo.bundlerepository):
        raise error.Abort(_('cannot use simple store with bundlerepo'))

    class simplestorerepo(repo.__class__):
        def file(self, f):
            return filestorage(self.svfs, f)

    repo.__class__ = simplestorerepo

def featuresetup(ui, supported):
    supported.add(REQUIREMENT)

def newreporequirements(orig, ui):
    """Modifies default requirements for new repos to use the simple store."""
    requirements = orig(ui)

    # These requirements are only used to affect creation of the store
    # object. We have our own store. So we can remove them.
    # TODO do this once we feel like taking the test hit.
    #if 'fncache' in requirements:
    #    requirements.remove('fncache')
    #if 'dotencode' in requirements:
    #    requirements.remove('dotencode')

    requirements.add(REQUIREMENT)

    return requirements

def makestore(orig, requirements, path, vfstype):
    if REQUIREMENT not in requirements:
        return orig(requirements, path, vfstype)

    return simplestore(path, vfstype)

def verifierinit(orig, self, *args, **kwargs):
    orig(self, *args, **kwargs)

    # We don't care that files in the store don't align with what is
    # advertised. So suppress these warnings.
    self.warnorphanstorefiles = False

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

    extensions.wrapfunction(localrepo, 'newreporequirements',
                            newreporequirements)
    extensions.wrapfunction(store, 'store', makestore)
    extensions.wrapfunction(verify.verifier, '__init__', verifierinit)