Wrap all DB write operations with oslo_db decorator to retry on deadlock. DBDeadlock exception can be raised quite often on Galera clusters under load. This also fixes an issue which causes conductor's periodic tasks to stop executing. Closes-Bug: #1637210 Closes-Bug: #1639338 Co-Authored-By: Vladyslav Drok <vdrok@mirantis.com> Co-Authored-By: Joanna Taryma <joanna.taryma@intel.com> Change-Id: I61db83637adfd98a5394d1f570f3de4302c93497