Simple cache decorator

src/Test/TestCached.py

@@ -0,0 +1,59 @@
+import time
+
+from util import Cached
+
+
+class CachedObject:
+    def __init__(self):
+        self.num_called_add = 0
+        self.num_called_multiply = 0
+        self.num_called_none = 0
+
+    @Cached(timeout=1)
+    def calcAdd(self, a, b):
+        self.num_called_add += 1
+        return a + b
+
+    @Cached(timeout=1)
+    def calcMultiply(self, a, b):
+        self.num_called_multiply += 1
+        return a * b
+
+    @Cached(timeout=1)
+    def none(self):
+        self.num_called_none += 1
+        return None
+
+
+class TestCached:
+    def testNoneValue(self):
+        cached_object = CachedObject()
+        assert cached_object.none() is None
+        assert cached_object.none() is None
+        assert cached_object.num_called_none == 1
+        time.sleep(2)
+        assert cached_object.none() is None
+        assert cached_object.num_called_none == 2
+
+    def testCall(self):
+        cached_object = CachedObject()
+
+        assert cached_object.calcAdd(1, 2) == 3
+        assert cached_object.calcAdd(1, 2) == 3
+        assert cached_object.calcMultiply(1, 2) == 2
+        assert cached_object.calcMultiply(1, 2) == 2
+        assert cached_object.num_called_add == 1
+        assert cached_object.num_called_multiply == 1
+
+        assert cached_object.calcAdd(2, 3) == 5
+        assert cached_object.calcAdd(2, 3) == 5
+        assert cached_object.num_called_add == 2
+
+        assert cached_object.calcAdd(1, 2) == 3
+        assert cached_object.calcMultiply(2, 3) == 6
+        assert cached_object.num_called_add == 2
+        assert cached_object.num_called_multiply == 2
+
+        time.sleep(2)
+        assert cached_object.calcAdd(1, 2) == 3
+        assert cached_object.num_called_add == 3

src/util/Cached.py

@@ -0,0 +1,68 @@
+import time
+
+
+class Cached(object):
+    def __init__(self, timeout):
+        self.cache_db = {}
+        self.timeout = timeout
+
+    def __call__(self, func):
+        def wrapper(*args, **kwargs):
+            key = "%s %s" % (args, kwargs)
+            cached_value = None
+            cache_hit = False
+            if key in self.cache_db:
+                cache_hit = True
+                cached_value, time_cached_end = self.cache_db[key]
+                if time.time() > time_cached_end:
+                    self.cleanupExpired()
+                    cached_value = None
+                    cache_hit = False
+
+            if cache_hit:
+                return cached_value
+            else:
+                cached_value = func(*args, **kwargs)
+                time_cached_end = time.time() + self.timeout
+                self.cache_db[key] = (cached_value, time_cached_end)
+                return cached_value
+
+        wrapper.emptyCache = self.emptyCache
+
+        return wrapper
+
+    def cleanupExpired(self):
+        for key in list(self.cache_db.keys()):
+            cached_value, time_cached_end = self.cache_db[key]
+            if time.time() > time_cached_end:
+                del(self.cache_db[key])
+
+    def emptyCache(self):
+        num = len(self.cache_db)
+        self.cache_db.clear()
+        return num
+
+
+if __name__ == "__main__":
+    from gevent import monkey
+    monkey.patch_all()
+
+    @Cached(timeout=2)
+    def calcAdd(a, b):
+        print("CalcAdd", a, b)
+        return a + b
+
+    @Cached(timeout=1)
+    def calcMultiply(a, b):
+        print("calcMultiply", a, b)
+        return a * b
+
+    for i in range(5):
+        print("---")
+        print("Emptied", calcAdd.emptyCache())
+        assert calcAdd(1, 2) == 3
+        print("Emptied", calcAdd.emptyCache())
+        assert calcAdd(1, 2) == 3
+        assert calcAdd(2, 3) == 5
+        assert calcMultiply(2, 3) == 6
+        time.sleep(1)

src/util/__init__.py

@@ -1,3 +1,4 @@
+from .Cached import Cached
 from .Event import Event
 from .Noparallel import Noparallel
 from .Pooled import Pooled