Comment 34 for bug 1812672

Reviewed: https://review.opendev.org/640500
Committed: https://git.openstack.org/cgit/openstack/oslo.cache/commit/?id=caf5443de8ff4ff353d741a125f782c67f579f52
Submitter: Zuul
Branch: stable/rocky

commit caf5443de8ff4ff353d741a125f782c67f579f52
Author: Ben Nemec <email address hidden>
Date: Tue Feb 26 22:12:23 2019 +0000

    Fix memcache pool client in monkey-patched environments

    First off, this is an ugly hack, but we're dealing with code that
    essentially monkey-patches a monkey-patch. You reap what you sow.

    Per the linked bug, our connection pool client explodes on python 3
    with eventlet monkey-patching in force:

    TypeError: object() takes no parameters

    This is due to the way __new__ is overridden in the class. We need
    to strip arguments from the call before they get to object(), which
    doesn't accept args.

    Unfortunately, when we're _not_ monkey-patched, adding the new
    override implementation fails with:

    TypeError: object.__new__(_MemcacheClient) is not safe,
    use Client.__new__()

    As such, we need different implementations depending on whether we
    are monkey-patched or not. This change passes both with and without
    monkey-patching and adds a unit test that exposes the bug.

    Note that this is a temporary, backportable fix that will ultimately
    be replaced by a switch to the pymemcache library which does not
    have the threading.local problem being worked around here.

    Change-Id: I039dffadeebd0ff4479b9c870c257772c43aba53
    Partial-Bug: 1812935
    Closes-Bug: 1812672
    (cherry picked from commit f4a25f642991a7114b86f6eb7d0bac3d599953a6)