Comment 28 for bug 1959562

Reviewed: https://review.opendev.org/c/openstack/oslo.cache/+/836868
Committed: https://opendev.org/openstack/oslo.cache/commit/fbcb07575561eb169424687d1150ac4e546d836a
Submitter: "Zuul (22348)"
Branch: stable/train

commit fbcb07575561eb169424687d1150ac4e546d836a
Author: Hervé Beraud <email address hidden>
Date: Fri Aug 6 14:51:15 2021 +0200

    Add retry mechanisms to oslo.cache

    This patch specifies a set of options required to setup a retry
    context. The context built from those options can later on be
    passed to any of the oslo.cache backends that supports pymemcache's
    retry mechanisms.

    This patch also sets up the retry mechanisms context based on
    the configuration option passed via oslo.config and adds it
    as an argument to be passed to the selected oslo.cache backend.

    This patch is needed to fix a TLS issue on stable branches introduced by
    pymemcache (since train), where if a cluster node disappear the client
    will fail without retrying to reconnect or to switch to an other node of
    the cluster.

    Partial-Bug: #1959562
    (cherry picked from commit 42bf82d5505a0def3d22972d67fde836f5091ed1)
    (cherry picked from commit 23e8e9a9f45956ef7ea74d3d443e518f13b43477)
    (cherry picked from commit 55b796be5679ffecc64f1940da425cac5c982fc1)
    (cherry picked from commit 91f61a50c0a4df70ff7e9c729aa3feda82e59582)
    (cherry picked from commit 973616a87323d2d5300d8062e349b6925ece81bd)
    Change-Id: I81e8d1c98726ab2abea984ce8bf46df49beedad3