add auto refresh

README.rst

@@ -52,6 +52,20 @@ Create a dictionary with capacity for 100 elements and elements expiring in 10 s
     from expiringdict import ExpiringDict
     cache = ExpiringDict(max_len=100, max_age_seconds=10)
 
+Create a dictionary with elements expiring in 10 seconds and anto refresh expired time when getitem:
+
+.. code-block:: py
+
+    from expiringdict import ExpiringDict
+    cache = ExpiringDict(max_age_seconds=10, auto_refresh=True)
+
+Create a dictionary with auto expired:
+
+.. code-block:: py
+
+    from expiringdict import ExpiringDict
+    cache = ExpiringDict(max_age_seconds=10, auto_expired=True)
+
 put and get a value there:
 
 .. code-block:: py

expiringdict/__init__.py

@@ -16,7 +16,7 @@
 """
 
 import time
-from threading import RLock
+from threading import RLock,Thread
 import sys
 from typing import Any, Union
 
@@ -28,7 +28,7 @@
 
 
 class ExpiringDict(OrderedDict):
-    def __init__(self, max_len, max_age_seconds, items=None):
+    def __init__(self, max_len, max_age_seconds, items=None, auto_refresh=False, auto_expired=False):
         # type: (Union[int, None], Union[float, None], Union[None,dict,OrderedDict,ExpiringDict]) -> None
 
         if not self.__is_instance_of_expiring_dict(items):
@@ -38,6 +38,7 @@ def __init__(self, max_len, max_age_seconds, items=None):
         self.max_len = max_len
         self.max_age = max_age_seconds
         self.lock = RLock()
+        self.auto_refresh = auto_refresh
 
         if sys.version_info >= (3, 5):
             self._safe_keys = lambda: list(self.keys())
@@ -55,6 +56,21 @@ def __init__(self, max_len, max_age_seconds, items=None):
             else:
                 raise ValueError('can not unpack items')
 
+        if auto_expired:
+            self.thread = Thread(target=self._expiring_key, args=())
+            self.thread.setDaemon(True)
+            self.thread.start()
+
+    def _expiring_key(self):
+        while True:
+            for key in self._safe_keys():
+                try:
+                    self.__getitem__(key, expired_check=True)
+                except KeyError:
+                    pass
+
+            time.sleep(0.1)
+
     def __contains__(self, key):
         """ Return True if the dict has a key, else return False. """
         try:
@@ -68,7 +84,7 @@ def __contains__(self, key):
             pass
         return False
 
-    def __getitem__(self, key, with_age=False):
+    def __getitem__(self, key, with_age=False, expired_check=False):
         """ Return the item of the dict.
 
         Raises a KeyError if key is not in the map.
@@ -77,6 +93,10 @@ def __getitem__(self, key, with_age=False):
             item = OrderedDict.__getitem__(self, key)
             item_age = time.time() - item[1]
             if item_age < self.max_age:
+                if self.auto_refresh and not expired_check:
+                    set_time = time.time()
+                    OrderedDict.__setitem__(self, key, (item[0], set_time))
+
                 if with_age:
                     return item[0], item_age
                 else:

tests/expiringdict_test.py

@@ -4,7 +4,11 @@
 from nose.tools import assert_raises, eq_, ok_
 
 from expiringdict import ExpiringDict
-
+try:
+    from collections import OrderedDict
+except ImportError:
+    # Python < 2.7
+    from ordereddict import OrderedDict
 
 def test_create():
     assert_raises(AssertionError, ExpiringDict, max_len=1, max_age_seconds=-1)
@@ -51,6 +55,37 @@ def test_basics():
     del d['e']
     ok_('e' not in d)
 
+def test_auto_refresh():
+    d = ExpiringDict(max_len=3, max_age_seconds=0.01, auto_refresh=True)
+    d['a'] = 'x'
+    eq_(d.get('a'), 'x')
+    sleep(0.005)
+    d['a']
+    sleep(0.005)
+    eq_(d.get('a'), 'x')
+    sleep(0.01)
+    eq_(d.get('a'), None)
+
+    d = ExpiringDict(max_len=3, max_age_seconds=0.01, auto_refresh=False)
+    d['a'] = 'x'
+    eq_(d.get('a'), 'x')
+    sleep(0.005)
+    d['a']
+    sleep(0.005)
+    eq_(d.get('a'), None)
+    sleep(0.01)
+    eq_(d.get('a'), None)
+
+def test_auto_expired():
+    d = ExpiringDict(max_len=3, max_age_seconds=0.1, auto_expired=True)
+    d['a'] = 'x'
+    d['b'] = 'y'
+    sleep(1)
+    ok_('a' not in d._safe_keys())
+    ok_('b' not in d._safe_keys())
+    eq_(d.get('a'), None)
+    eq_(d.get('b'), None)
+
 
 def test_pop():
     d = ExpiringDict(max_len=3, max_age_seconds=0.01)