TTLDict

Python dictionary with key expiry time

OrderedTTLDict - behaves like an ordered dict you know. The methods items and values return a list of objects after purging expired objects. The method keys returns odict_keys as the parent class, but it does so after purging expired keys. Python's own OrderedDict and other dictionaries return a dictionary views whereas the methods here do not.

Expired keys are not removed, instead they are expired. You can remove expired keys by calling keys() or any other method that iterates over the dictionary instance. Expired keys will be removed when you try to access them.

Demo:

In [1]: from ttldict import  TTLOrderedDict

In [2]: mydict = TTLOrderedDict(default_ttl=3)  # expire keys after 3 second

In [3]: mydict['foo'] = 'bar'

In [4]: mydict.is_expired('foo')  # not yet expired

In [5]: mydict.is_expired('foo')  # not yet expired

In [6]: mydict.is_expired('foo')  # expired !!!
Out[6]: 'foo'


In [7]: mydict['foo']
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-55-ed0618fdfbab> in <module>()
----> 1 mydict['foo']

/..../ttldict/__init__.py in __getitem__(self, key)
     95             if self.is_expired(key):
     96                 self.__delitem__(key)
---> 97                 raise KeyError
     98             item = super().__getitem__(key)[1]
     99             return item

KeyError:

In [8]: mydict.is_expired('foo')  # not available anymore
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-56-351121feac66> in <module>()
----> 1 mydict.is_expired('foo')  # not available anymore

.../ttldict/__init__.py in is_expired(self, key, now)
     59                 now = time.time()
     60
---> 61             expire, _value = super().__getitem__(key)
     62
     63             if expire:

KeyError: 'foo'

Testing

Use pytest to run the tests:

make test

Credits and Thanks:

• mailgun for expiringdict

• Thomas Kemmer for https://github.com/tkem/cachetools

and for Jyrki Muukkonen for ttldict published in https://github.com/jvtm/ttldict.

This library contains fixes for his TTLDict class and my own OrderedTTLDict.

Without all those this work would not have been possible.