Move to OrderedDict-based cacheclass.

Cacheclass/cacheclass.py

@@ -1,61 +1,31 @@
 import collections
-import itertools
-import time
 
 class Cache:
-    def __init__(self, maxage=None, maxlen=None, shrink_delay=None):
-        self.maxage = maxage
+    def __init__(self, maxlen):
         self.maxlen = maxlen
-        self.shrink_delay = shrink_delay
-        self.last_shrink = time.time()
-
-        self._dict = {}
-        self._recency = {}
+        self.cache = collections.OrderedDict()
 
     def __contains__(self, key):
-        return key in self._dict
+        return key in self.cache
 
     def __getitem__(self, key):
-        self._shrink()
-        value = self._dict[key]
-        self._maintain(key)
+        value = self.cache.pop(key)
+        self.cache[key] = value
         return value
 
+    def __len__(self):
+        return len(self.cache)
+
     def __setitem__(self, key, value):
-        self._shrink()
-        self._dict[key] = value
-        self._maintain(key)
-
-    def _maintain(self, key):
-        self._recency[key] = time.time()
-
-    def _shrink(self):
-        if self.shrink_delay is not None:
-            if time.time() - self.last_shrink > self.shrink_delay:
-                return
-
-        now = time.time()
-        self.last_shrink = now
-
-        if self.maxlen is None:
-            pop_count = 0
-        else:
-            pop_count = len(self._dict) - self.maxlen
-            pop_count = max(0, pop_count)
-        keys = sorted(self._recency.keys(), key=self._recency.get)
-        for key in itertools.islice(keys, 0, pop_count):
-            self.remove(key)
-
-        if self.maxage is not None:
-            for key in itertools.islice(keys, pop_count, None):
-                last_used = self._recency[key]
-                age = now - last_used
-                if age > self.maxage:
-                    self.remove(key)
+        try:
+            self.cache.pop(key)
+        except KeyError:
+            if len(self.cache) >= self.maxlen:
+                self.cache.popitem(last=False)
+        self.cache[key] = value
 
     def clear(self):
-        self._dict.clear()
-        self._recency.clear()
+        self.cache.clear()
 
     def get(self, key, fallback=None):
         try:
@@ -63,9 +33,11 @@ class Cache:
         except KeyError:
             return fallback
 
+    def pop(self, key):
+        return self.cache.pop(key)
+
     def remove(self, key):
         try:
-            self._dict.pop(key)
-            self._recency.pop(key)
+            self.pop(key)
         except KeyError:
-            return
+            pass