Use functools.lru_cache to cache extension point discovery

colcon_core/extension_point.py

@@ -3,6 +3,7 @@
 # Licensed under the Apache License, Version 2.0
 
 from collections import defaultdict
+from functools import lru_cache
 import os
 import traceback
 
@@ -46,6 +47,7 @@ def _get_unique_distributions():
             yield dist
 
 
+@lru_cache
 def get_all_extension_points():
     """
     Get all extension points related to `colcon` and any of its extensions.
@@ -78,6 +80,7 @@ def get_all_extension_points():
     return entry_points
 
 
+@lru_cache
 def get_extension_points(group):
     """
     Get the extension points for a specific group.
@@ -136,6 +139,7 @@ def load_extension_points(group, *, excludes=None):
     return extension_types
 
 
+@lru_cache
 def load_extension_point(name, value, group):
     """
     Load the extension point.

test/test_extension_point.py

@@ -101,6 +101,7 @@ def test_extension_point_blocklist():
 
         # successful loading of entry point not in blocklist
         load.reset_mock()
+        load_extension_point.cache_clear()
         with EnvironmentContext(COLCON_EXTENSION_BLOCKLIST=os.pathsep.join([
             'group1.extB', 'group2.extC'])
         ):
@@ -109,6 +110,7 @@ def test_extension_point_blocklist():
 
         # entry point in a blocked group can't be loaded
         load.reset_mock()
+        load_extension_point.cache_clear()
         with EnvironmentContext(COLCON_EXTENSION_BLOCKLIST='group1'):
             with pytest.raises(RuntimeError) as e:
                 load_extension_point('extA', 'eA', 'group1')
@@ -117,6 +119,7 @@ def test_extension_point_blocklist():
         assert load.call_count == 0
 
         # entry point listed in the blocklist can't be loaded
+        load_extension_point.cache_clear()
         with EnvironmentContext(COLCON_EXTENSION_BLOCKLIST=os.pathsep.join([
             'group1.extA', 'group1.extB'])
         ):