Cleanup to strong cache addition

3 files changed, 16 insertions, 7 deletions

diff --git a/dateutil/test/test_tz.py b/dateutil/test/test_tz.py
index 1582af7..97a0c68 100644
--- a/dateutil/test/test_tz.py
+++ b/dateutil/test/test_tz.py
@@ -746,12 +746,12 @@ def test_tzoffset_weakref():
     del UTC1
     gc.collect()
 
-    assert UTC_ref() is not None # Because strong cache should keep it
+    assert UTC_ref() is not None    # Should be in the strong cache
     assert UTC_ref() is tz.tzoffset('UTC', 0)
 
     # Fill the strong cache with other items
     for offset in range(5,15):
-        tz.tzoffset('UTC', offset)
+        tz.tzoffset('RandomZone', offset)
 
     gc.collect()
     assert UTC_ref() is  None
@@ -1149,7 +1149,7 @@ def test_gettz_weakref():
     del NYC1
     gc.collect()
 
-    assert NYC_ref() is not None # Because strong cache should keep it
+    assert NYC_ref() is not None        # Should still be in the strong cache
     assert tz.gettz('America/New_York') is NYC_ref()
 
     # Populate strong cache with other timezones
@@ -1158,7 +1158,7 @@ def test_gettz_weakref():
     tz.gettz('Australia/Currie')
 
     gc.collect()
-    assert NYC_ref() is None # Because strong cache should keep it
+    assert NYC_ref() is None    # Should have been pushed out
     assert tz.gettz('America/New_York') is not NYC_ref()
 
 class ZoneInfoGettzTest(GettzTest, WarningTestMixin):
diff --git a/dateutil/tz/_factories.py b/dateutil/tz/_factories.py
index 8da5e82..d2560eb 100644
--- a/dateutil/tz/_factories.py
+++ b/dateutil/tz/_factories.py
@@ -2,6 +2,7 @@ from datetime import timedelta
 import weakref
 from collections import OrderedDict
 
+
 class _TzSingleton(type):
     def __init__(cls, *args, **kwargs):
         cls.__instance = None
@@ -12,6 +13,7 @@ class _TzSingleton(type):
             cls.__instance = super(_TzSingleton, cls).__call__()
         return cls.__instance
 
+
 class _TzFactory(type):
     def instance(cls, *args, **kwargs):
         """Alternate constructor that returns a fresh instance"""
@@ -22,6 +24,7 @@ class _TzOffsetFactory(_TzFactory):
     def __init__(cls, *args, **kwargs):
         cls.__instances = weakref.WeakValueDictionary()
         cls.__strong_cache = OrderedDict()
+        cls.__strong_cache_size = 8
 
     def __call__(cls, name, offset):
         if isinstance(offset, timedelta):
@@ -36,7 +39,9 @@ class _TzOffsetFactory(_TzFactory):
 
         cls.__strong_cache[key] = cls.__strong_cache.pop(key, instance)
 
-        if len(cls.__strong_cache) == 9:  #only to hold 8 items
+        # Remove an item if the strong cache is overpopulated
+        # TODO: Maybe this should be under a lock?
+        if len(cls.__strong_cache) > cls.__strong_cache_size:
             cls.__strong_cache.popitem(last=False)
 
         return instance
@@ -46,6 +51,7 @@ class _TzStrFactory(_TzFactory):
     def __init__(cls, *args, **kwargs):
         cls.__instances = weakref.WeakValueDictionary()
         cls.__strong_cache = OrderedDict()
+        cls.__strong_cache_size = 8
 
     def __call__(cls, s, posix_offset=False):
         key = (s, posix_offset)
@@ -57,7 +63,10 @@ class _TzStrFactory(_TzFactory):
 
         cls.__strong_cache[key] = cls.__strong_cache.pop(key, instance)
 
-        if len(cls.__strong_cache) == 9:  #only to hold 8 items
+
+        # Remove an item if the strong cache is overpopulated
+        # TODO: Maybe this should be under a lock?
+        if len(cls.__strong_cache) > cls.__strong_cache_size:
             cls.__strong_cache.popitem(last=False)
 
         return instance
diff --git a/dateutil/tz/tz.py b/dateutil/tz/tz.py
index 41342b7..161f4d8 100644
--- a/dateutil/tz/tz.py
+++ b/dateutil/tz/tz.py
@@ -1565,7 +1565,7 @@ def __get_gettz():
 
                 self.__strong_cache[name] = self.__strong_cache.pop(name, rv)
 
-                if len(self.__strong_cache) == (self.__strong_cache_size + 1):
+                if len(self.__strong_cache) > self.__strong_cache_size:
                     self.__strong_cache.popitem(last=False)
 
             return rv