Comment 6 for bug 1588561

Reviewed: https://review.openstack.org/326229
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=32ade7a24342781dc6887aae78d83d2119f0c8cd
Submitter: Jenkins
Branch: master

commit 32ade7a24342781dc6887aae78d83d2119f0c8cd
Author: Steve Baker <email address hidden>
Date: Fri Jun 3 12:58:30 2016 +1200

    Implement event list nested-depth

    The GET call to list events will support a nested_depth parameter. The
    response will have an additional links url with the ref 'root_stack'
    to indicate that this API supports nested_depth queries.

    This has the following consequences for old/new combinations of
    client/server
    - new heatclient, new server - nested_depth param is set, server
      returns nested events
    - new heatclient, old server - nested_depth param is set, server
      returns events with no root_stack, heatclient falls back to
      recursive event fetch
    - old heatclient, new server - nested_depth param is never set,
      recursive event fetch works as before

    Here are some timings for a TripleO overcloud stack with ~700 events.

    Current heat and python-heatclient master:
    time openstack stack event list --nested-depth 4 overcloud |wc -l
    744
    real 0m17.500s

    This change, with heatclient 31278ff5f77b152b5ef7a4197e15c441c72ff163:
    time openstack stack event list --nested-depth 4 overcloud |wc -l
    608
    real 0m1.725s

    The difference in event count (744 vs 608) is due to the stack events
    being filtered out for stacks with zero resources - these are a source
    of unnecessary noise so their removal should be considered an improvement.

    Closes-Bug: #1588561

    Change-Id: I27e1ffb770e00a7f929c081b2a505e2007f5d584