event-engine works incorrectly in HA

[Nikolay Makhotkin]

If we start, say, 3 instances of event-engine, have registered some trigger on some event and trigger this event, all event-engines receive this event and trigger a workflow. Each event-engine works independently now and starts a workflow so we have 3 started workflow at this point.

Need some kind of synchronization for event-engine to start at most 1 workflow for each event.

[Jose Castro Leon (jose-castro-leon)]

A previous patch allows to have a common queue for the listeners to only launch a workflow
https://github.com/openstack/mistral/commit/e0eeca6706a873b90f895674af2b00e6dd57ae69

But the RPC calls are still synchronous, so only one event_engine modifies its listeners, leaving the other ones behind

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/548044

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/548044
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=defff0877392400e572dca772d24b2c6fe49dca1
Submitter: Zuul
Branch: master

commit defff0877392400e572dca772d24b2c6fe49dca1
Author: Jose Castro Leon <email address hidden>
Date: Mon Feb 26 16:00:27 2018 +0100

    [Event-engine] Allow event_engine to work in HA

    A previous patch allows to make multiple event_engines to listen
    to a single queue, but the RPC calls on CRUD are still synchronous

    This patch modifies the calls and broadcasts them on all the event
    engines allow them to modify each independent listeners.

    Closes-Bug: #1715848
    Change-Id: Ia37831a03993f5a1bf980d62344d25377062788d

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/rocky
Review: https://review.openstack.org/623936

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/mistral 8.0.0.0b1 development milestone.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/623936
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=ec06ccf65a69fdfe95f2f669591ff2a4a3aca7cc
Submitter: Zuul
Branch: stable/rocky

commit ec06ccf65a69fdfe95f2f669591ff2a4a3aca7cc
Author: Jose Castro Leon <email address hidden>
Date: Mon Feb 26 16:00:27 2018 +0100

    [Event-engine] Allow event_engine to work in HA

    A previous patch allows to make multiple event_engines to listen
    to a single queue, but the RPC calls on CRUD are still synchronous

    This patch modifies the calls and broadcasts them on all the event
    engines allow them to modify each independent listeners.

    Closes-Bug: #1715848
    Change-Id: Ia37831a03993f5a1bf980d62344d25377062788d
    (cherry picked from commit defff0877392400e572dca772d24b2c6fe49dca1)