The method "_connect_ping_listener" should rollback the transaction at the end

[Rodolfo Alonso]

The method "_connect_ping_listener" should rollback the transaction at the end. When the method finishes, the connection transaction should be aborted and deleted; the connection will be inactive again.

This issue has been spotted during the Neutron functional testing using SQLAlchemy main branch [1]. When the engine is started [2], the connection is tested [3] with the mentioned "_connect_ping_listener" method [4]. After this method, the connection transaction should be deleted to avoid the following error when trying to being a transaction with this connection (from [1]):
sqlalchemy.exc.InvalidRequestError: This connection has already initialized a SQLAlchemy Transaction() object via begin() or autobegin; can't call begin() here unless rollback() or commit() is called first.

[1]https://storage.bhs.cloud.ovh.net/v1/AUTH_dcaab5e32b234d56b626f72581e3644c/zuul_opendev_logs_680/874669/1/experimental/neutron-functional-with-sqlalchemy-master/680ee10/job-output.txt
[2]https://github.com/openstack/oslo.db/blob/7d619ae3eb2a64dadeaa9fbaeb1b9424b83414a6/oslo_db/sqlalchemy/provision.py#L145
[3]https://github.com/openstack/oslo.db/blob/7d619ae3eb2a64dadeaa9fbaeb1b9424b83414a6/oslo_db/sqlalchemy/engines.py#L225
[4]https://github.com/openstack/oslo.db/blob/7d619ae3eb2a64dadeaa9fbaeb1b9424b83414a6/oslo_db/sqlalchemy/engines.py#L55

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/oslo.db/+/874858

[Erik Olof Gunnar Andersson (eandersson)]

Would love to see this fix merged sooner, rather than later as it blocks Designate for merging in sqlalchemy 2.x support.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/oslo.db/+/874858
Committed: https://opendev.org/openstack/oslo.db/commit/877bcfc6a6ed16ba6885f47824df6b1f5ac60b4e
Submitter: "Zuul (22348)"
Branch: master

commit 877bcfc6a6ed16ba6885f47824df6b1f5ac60b4e
Author: Rodolfo Alonso Hernandez <email address hidden>
Date: Sat Feb 18 13:52:22 2023 +0100

    Rollback the connection after server ping method

    In the method ``engines._connect_ping_listener``, the connection should
    be rolled back after the ping execution. The rollback will revert the
    transaction and delete it.

    Closes-Bug: #2008209
    Change-Id: Iba29ded227634e02795052acfd89b572bf21f54c

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/oslo.db 13.0.0 release.