Clean up on length call to give accurate dictionary length based on expiration

expiringdict/__init__.py

@@ -55,6 +55,28 @@ def __init__(self, max_len, max_age_seconds, items=None):
             else:
                 raise ValueError('can not unpack items')
 
+    def __len__(self):
+        with self.lock:
+            current_key = iter(self)
+            keys_to_del = []
+            for k in current_key:
+                item = OrderedDict.__getitem__(self, k)
+                time_added = item[1]
+                item_age = time.time() - time_added
+                if item_age > self.max_age:
+                    keys_to_del.append(k)
+                else:
+                    break
+            for k in keys_to_del:
+                del self[k]
+
+        return super(ExpiringDict, self).__len__()
+
+    def __repr__(self):
+        if len(self) == 0:
+            return "ExpiringDict([])"
+        return super(ExpiringDict, self).__repr__()
+
     def __contains__(self, key):
         """ Return True if the dict has a key, else return False. """
         try:

tests/expiringdict_test.py

@@ -122,3 +122,46 @@ def test_not_implemented():
     assert_raises(NotImplementedError, d.viewitems)
     assert_raises(NotImplementedError, d.viewkeys)
     assert_raises(NotImplementedError, d.viewvalues)
+
+
+def test_cleanup_on_length():
+    d = ExpiringDict(max_len=10, max_age_seconds=0.01)
+    d['a'] = 'x'
+    eq_(1, len(d))
+    sleep(0.01)
+    eq_(0, len(d))
+
+    d = ExpiringDict(max_len=10, max_age_seconds=0.02)
+    d['a'] = 1
+    sleep(0.01)
+    eq_(1, len(d))
+    d['b'] = 2
+    sleep(0.01)
+    eq_(1, len(d))
+    d['c'] = 3
+    sleep(0.01)
+    eq_(1, len(d))
+    d['d'] = 4
+    sleep(0.01)
+    eq_(1, len(d))
+
+    d = ExpiringDict(max_len=1000, max_age_seconds=.5)
+    d[1] = 1
+    d[2] = 2
+    d[3] = 3
+    d[4] = 4
+
+    ok_(1 in d)
+    ok_(2 in d)
+    ok_(3 in d)
+    ok_(4 in d)
+    eq_(4, len(d))
+
+    sleep(.25)
+    d[1] = 1
+    d[2] = 2
+    sleep(.40)
+    ok_(1 in d)
+    ok_(2 in d)
+    ok_(3 not in d)
+    ok_(4 not in d)