refactor cache.py

* type annotation
* set lower bound of max_size to -1
* refactor setdefault(), __getitem__(), timestamp()

Signed-off-by: flashdagger <flashdagger@googlemail.com>

zammadoo/cache.py

@@ -10,17 +10,17 @@
 
 
 class LruCache(Generic[_T]):
-    def __init__(self, max_size=-1) -> None:
+    def __init__(self, max_size: int = -1) -> None:
         self._cache: "OrderedDict[Hashable, Tuple[datetime, _T]]" = OrderedDict()
         self._max_size = max_size
 
     @property
-    def max_size(self):
+    def max_size(self) -> int:
         return self._max_size
 
     @max_size.setter
     def max_size(self, value: int):
-        self._max_size = value
+        self._max_size = max(value, -1)
         if value == 0:
             self._cache.clear()
         elif value > 0:
@@ -41,15 +41,15 @@ def setdefault(self, item, default: _T) -> _T:
             return default
 
         cache = self._cache
+
         if item in cache:
-            if max_size > 1:
-                cache.move_to_end(item)
+            cache.move_to_end(item)
             return cache[item][1]
 
-        cache[item] = datetime.now(timezone.utc), default
-        if 0 < max_size < len(cache):
+        if 0 < max_size <= len(cache):
             cache.popitem(last=False)
 
+        cache[item] = datetime.now(timezone.utc), default
         return default
 
     def clear(self) -> None:
@@ -72,8 +72,7 @@ def __contains__(self, item: Hashable):
 
     def __getitem__(self, item: Hashable) -> _T:
         cache = self._cache
-        if self._max_size > 1:
-            cache.move_to_end(item)
+        cache.move_to_end(item)
         return cache[item][1]
 
     def __setitem__(self, item: Hashable, value: _T) -> None:
@@ -94,5 +93,5 @@ def __delitem__(self, item: Hashable) -> None:
         del self._cache[item]
 
     def timestamp(self, item: Hashable) -> Optional[datetime]:
-        data = self._cache.get(item)
-        return data and data[0]
+        data = self._cache.get(item, (None, None))
+        return data[0]