openstack/heat
Code Issues Proposed changes

Optimise the function.dep_attrs() function

Browse Source 
Due to unfortunate copy-pasta, the original implementation of
function.dep_attrs() iterates over items in a dictionary instead of values.
Dictionary keys cannot have dependencies - they must be hashable and
Function objects are not. So for each dictionary key we call dep_attrs()
recursively 3 times as many times as we need to (for the key/value tuple,
the key, and the value). For template snippets that are dominated by
dictionaries, this means it took three times as long and used three times
as much memory and twice as much stack space as it needed to.

Change-Id: I13781540483daf88202d221a9f517746eebf0346
Partial-Bug: #1684272
This commit is contained in:
Zane Bitter 2017-07-19 17:35:40 -04:00
parent db989b64ce
commit c889f08ab5
1 changed files with 1 additions and 1 deletions
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2
heat/engine/function.py
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@ -289,7 +289,7 @@ def dep_attrs(snippet, resource_name):
return snippet.dep_attrs(resource_name)
elif isinstance(snippet, collections.Mapping):
attrs = (dep_attrs(value, resource_name) for value in snippet.items())
attrs = (dep_attrs(val, resource_name) for val in snippet.values())
return itertools.chain.from_iterable(attrs)
elif (not isinstance(snippet, six.string_types) and
isinstance(snippet, collections.Iterable)):