Use sets when checking for existence of an element

buildstream/_loader/loader.py

@@ -284,17 +284,17 @@ class Loader():
     def _check_circular_deps(self, element, check_elements=None, validated=None, sequence=None):
 
         if check_elements is None:
-            check_elements = {}
+            check_elements = set()
         if validated is None:
-            validated = {}
+            validated = set()
         if sequence is None:
             sequence = []
 
         # Skip already validated branches
-        if validated.get(element) is not None:
+        if element in validated:
             return
 
-        if check_elements.get(element) is not None:
+        if element in check_elements:
             # Create `chain`, the loop of element dependencies from this
             # element back to itself, by trimming everything before this
             # element from the sequence under consideration.
@@ -306,15 +306,15 @@ class Loader():
                             .format(element.full_name, " -> ".join(chain)))
 
         # Push / Check each dependency / Pop
-        check_elements[element] = True
+        check_elements.add(element)
         sequence.append(element.full_name)
         for dep in element.dependencies:
             dep.element._loader._check_circular_deps(dep.element, check_elements, validated, sequence)
-        del check_elements[element]
+        check_elements.remove(element)
         sequence.pop()
 
         # Eliminate duplicate paths
-        validated[element] = True
+        validated.add(element)
 
     # _sort_dependencies():
     #

buildstream/_profile.py

@@ -26,7 +26,7 @@ import datetime
 import time
 
 # Track what profile topics are active
-active_topics = {}
+active_topics = set()
 active_profiles = {}
 initialized = False
 
@@ -144,14 +144,10 @@ def profile_init():
         if setting:
             topics = setting.split(':')
             for topic in topics:
-                active_topics[topic] = True
+                active_topics.add(topic)
         initialized = True
 
 
 def profile_enabled(topic):
     profile_init()
-    if active_topics.get(topic):
-        return True
-    if active_topics.get(Topics.ALL):
-        return True
-    return False
+    return topic in active_topics or Topics.ALL in active_topics

buildstream/plugins/sources/tar.py

@@ -154,7 +154,7 @@ class TarSource(DownloadableFileSource):
     # directory paths for the archived files.
     def _list_tar_paths(self, tar):
 
-        visited = {}
+        visited = set()
         for member in tar.getmembers():
 
             # Remove any possible leading './', offer more consistent behavior
@@ -170,7 +170,7 @@ class TarSource(DownloadableFileSource):
                 for i in range(len(components) - 1):
                     dir_component = '/'.join([components[j] for j in range(i + 1)])
                     if dir_component not in visited:
-                        visited[dir_component] = True
+                        visited.add(dir_component)
                         try:
                             # Dont yield directory members which actually do
                             # exist in the archive