Implement client side of event list --nested-depth

This change does the following:
- cleans up the usage of get_events so that marker and limit are only
  specified in their dedicated arguments, not also in event_args
  (also, specifying only in event_args still works)
- first attempts server-side nested_depth support
- falls back to the old recursive approach if the response data lacks a
  link with the ref root_stack

Since there is a fallback for old heat APIs, the client change can
land before or after the heat change
I27e1ffb770e00a7f929c081b2a505e2007f5d584

Change-Id: I43d12ec61ec359222184f07c170de3c97481f1ba
Closes-Bug: #1588561

1 files changed, 50 insertions, 22 deletions

diff --git a/heatclient/common/event_utils.py b/heatclient/common/event_utils.py
index 65f89c5..d490ecf 100644
--- a/heatclient/common/event_utils.py
+++ b/heatclient/common/event_utils.py
@@ -67,29 +67,57 @@ def get_hook_events(hc, stack_id, event_args, nested_depth=0,
 
 def get_events(hc, stack_id, event_args, nested_depth=0,
                marker=None, limit=None):
+    event_args = dict(event_args)
+    if marker:
+        event_args['marker'] = marker
+    if limit:
+        event_args['limit'] = limit
+    if not nested_depth:
+        # simple call with no nested_depth
+        return _get_stack_events(hc, stack_id, event_args)
+
+    # assume an API which supports nested_depth
+    event_args['nested_depth'] = nested_depth
     events = _get_stack_events(hc, stack_id, event_args)
-    if nested_depth > 0:
-        events.extend(_get_nested_events(hc, nested_depth,
-                                         stack_id, event_args))
-        # Because there have been multiple stacks events mangled into
-        # one list, we need to sort before passing to print_list
-        # Note we can't use the prettytable sortby_index here, because
-        # the "start" option doesn't allow post-sort slicing, which
-        # will be needed to make "--marker" work for nested_depth lists
-        events.sort(key=lambda x: x.event_time)
-
-        # Slice the list if marker is specified
-        if marker:
-            try:
-                marker_index = [e.id for e in events].index(marker)
-                events = events[marker_index:]
-            except ValueError:
-                pass
-
-        # Slice the list if limit is specified
-        if limit:
-            limit_index = min(int(limit), len(events))
-            events = events[:limit_index]
+
+    if not events:
+        return events
+
+    first_links = getattr(events[0], 'links', [])
+    root_stack_link = [l for l in first_links
+                       if l.get('rel') == 'root_stack']
+    if root_stack_link:
+        # response has a root_stack link, indicating this is an API which
+        # supports nested_depth
+        return events
+
+    # API doesn't support nested_depth, do client-side paging and recursive
+    # event fetch
+    marker = event_args.pop('marker', None)
+    limit = event_args.pop('limit', None)
+    event_args.pop('nested_depth', None)
+    events = _get_stack_events(hc, stack_id, event_args)
+    events.extend(_get_nested_events(hc, nested_depth,
+                                     stack_id, event_args))
+    # Because there have been multiple stacks events mangled into
+    # one list, we need to sort before passing to print_list
+    # Note we can't use the prettytable sortby_index here, because
+    # the "start" option doesn't allow post-sort slicing, which
+    # will be needed to make "--marker" work for nested_depth lists
+    events.sort(key=lambda x: x.event_time)
+
+    # Slice the list if marker is specified
+    if marker:
+        try:
+            marker_index = [e.id for e in events].index(marker)
+            events = events[marker_index:]
+        except ValueError:
+            pass
+
+    # Slice the list if limit is specified
+    if limit:
+        limit_index = min(int(limit), len(events))
+        events = events[:limit_index]
     return events