08bec8a2be
If there are multiple OVS agents concurrently executing
'tunnel_sync' RPC call a race condition can occur
leading to insertion of two different TunnelEndpoint
entries having the same 'id' value.
Unfortunately, we can not rely on:
- @lockutils.synchronized(), because a Neutron installation can use
more than one API node
- with_lockmode('update'), because it works differently in PostgreSQL
comparing to MySQL and doesn't guarantee that no new rows have been
added to the table since the select query was issued. Please take a
look at http://www.postgresql.org/files/developer/concurrency.pdf for
more details.
The proposed fix:
- ensures there is a unique constraint set for 'id' column
- wraps creation of a new TunnelEndpoint entry into a
repeatedly executed transactional block (so even if a concurrent
DB transaction has been flushed or commited earlier than this one
we can handle an integrity error and try again, in spite of the
specified transactions isolation level value)
Fixes bug 1167916
Change-Id: I62dc729d595f090436199d5e1b6b98a884ead7a5
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