tests/test-storage.py

sqlitestore: support for storing revisions without their parents

This commit kinda/sorta implements the equivalent of ellipsis nodes for
the SQLite storage backend.

Without implementing full blown ellipsis nodes (and the necessary support for
them in the wire protocol), we instead teach the store to rewrite the p1 and
p2 nodes to nullid when the incoming parent isn't in the local store. This allows
servers to remain dumb and send the real parent and have the clients deal
with the missing parent problem.

This obviously isn't ideal because a benefit of ellipsis nodes is we can
insert a fake parent to ellide missing changesets. But neither solution is
ideal because it drops the original parent from storage. We could probably
teach the SQLite store to retain the original parent and handle missing
parents at read time. However, parent revisions are stored as integers and
it isn't trivial to store an "empty" revision in the store yet, which would
be necessary to represent the "missing" parent.

The store is somewhat intelligent in trying to remove the missing parents
metadata when the revision is re-added. But, revision numbers will be all
messed up in that case, so I'm not sure it is worth it. At some point we'll
likely want to remove the concept of revision numbers from the database and
have the store invent them at index generation time. Or even better, we can
do away with revision numbers from the file storage interface completely.
We'll get there eventually...

Differential Revision: https://phab.mercurial-scm.org/D5168

# This test verifies the conformance of various classes to various
# storage interfaces.
from __future__ import absolute_import

import silenttestrunner

from mercurial import (
    error,
    filelog,
    revlog,
    transaction,
    ui as uimod,
    vfs as vfsmod,
)

from mercurial.testing import (
    storage as storagetesting,
)

try:
    from hgext import (
        sqlitestore,
    )
except ImportError:
    sqlitestore = None

try:
    from mercurial import zstd
    zstd.__version__
except ImportError:
    zstd = None

STATE = {
    'lastindex': 0,
    'ui': uimod.ui(),
    'vfs': vfsmod.vfs(b'.', realpath=True),
}

def makefilefn(self):
    """Factory for filelog instances."""
    fl = filelog.filelog(STATE['vfs'], b'filelog-%d' % STATE['lastindex'])
    STATE['lastindex'] += 1
    return fl

def maketransaction(self):
    vfsmap = {b'plain': STATE['vfs'], b'store': STATE['vfs']}

    return transaction.transaction(STATE['ui'].warn, STATE['vfs'], vfsmap,
                                   b'journal', b'undo')

def addrawrevision(self, fl, tr, node, p1, p2, linkrev, rawtext=None,
                   delta=None, censored=False, ellipsis=False, extstored=False):
    flags = 0

    if censored:
        flags |= revlog.REVIDX_ISCENSORED
    if ellipsis:
        flags |= revlog.REVIDX_ELLIPSIS
    if extstored:
        flags |= revlog.REVIDX_EXTSTORED

    if rawtext is not None:
        fl._revlog.addrawrevision(rawtext, tr, linkrev, p1, p2, node, flags)
    elif delta is not None:
        fl._revlog.addrawrevision(rawtext, tr, linkrev, p1, p2, node, flags,
                                  cachedelta=delta)
    else:
        raise error.Abort('must supply rawtext or delta arguments')

    # We may insert bad data. Clear caches to prevent e.g. cache hits to
    # bypass hash verification.
    fl._revlog.clearcaches()

# Assigning module-level attributes that inherit from unittest.TestCase
# is all that is needed to register tests.
filelogindextests = storagetesting.makeifileindextests(makefilefn,
                                                       maketransaction,
                                                       addrawrevision)
filelogdatatests = storagetesting.makeifiledatatests(makefilefn,
                                                     maketransaction,
                                                     addrawrevision)
filelogmutationtests = storagetesting.makeifilemutationtests(makefilefn,
                                                             maketransaction,
                                                             addrawrevision)

def makesqlitefile(self):
    path = STATE['vfs'].join(b'db-%d.db' % STATE['lastindex'])
    STATE['lastindex'] += 1

    db = sqlitestore.makedb(path)

    compression = b'zstd' if zstd else b'zlib'

    return sqlitestore.sqlitefilestore(db, b'dummy-path', compression)

def addrawrevisionsqlite(self, fl, tr, node, p1, p2, linkrev, rawtext=None,
                         delta=None, censored=False, ellipsis=False,
                         extstored=False):
    flags = 0

    if censored:
        flags |= sqlitestore.FLAG_CENSORED

    if ellipsis | extstored:
        raise error.Abort(b'support for ellipsis and extstored flags not '
                          b'supported')

    if rawtext is not None:
        fl._addrawrevision(node, rawtext, tr, linkrev, p1, p2, flags=flags)
    elif delta is not None:
        fl._addrawrevision(node, rawtext, tr, linkrev, p1, p2,
                           storedelta=delta, flags=flags)
    else:
        raise error.Abort(b'must supply rawtext or delta arguments')

if sqlitestore is not None:
    sqlitefileindextests = storagetesting.makeifileindextests(
        makesqlitefile, maketransaction, addrawrevisionsqlite)
    sqlitefiledatatests = storagetesting.makeifiledatatests(
        makesqlitefile, maketransaction, addrawrevisionsqlite)
    sqlitefilemutationtests = storagetesting.makeifilemutationtests(
        makesqlitefile, maketransaction, addrawrevisionsqlite)

if __name__ == '__main__':
    silenttestrunner.main(__name__)