rcu-cache

The rcu module implements a multi-producer, multi-consumer thread-safe FIFO cache modeled after an OrderedDict. The object features lock-less reads and the writes are guarded by a lock leading to fast reads and thread-safe writes.

The module works with Python 2.7+/3.2+.

Example:

   >>> from rcu import RCUCache

# Setting the maxsize to 0 results in an unlimited sized cache. The constructor
# also accepts 
   >>> cache = RCUCache(maxsize=2, items=None)
   >>> print(cache)
   RCUCache(maxsize=2, items=OrderedDict())

   >>> cache[2] = 10
   >>> cache[10] = 200
   >>> print(cache)
   RCUCache(maxsize=2, items=OrderedDict([(2, 10), (10, 200)]))

# Adding another element will get rid of the first element that was added.
   >>> cache[50] = 1000
   >>> print(cache)
   RCUCache(maxsize=2, items=OrderedDict([(10, 200), (50, 1000)]))
   >>> len(cache)
   2

# Simply access the element and catch the `KeyError` if you need to test for
# membership.
   >>> try:
   ...     cache[20]
   ... except KeyError as e:
   ...     print("Key %s not found in the cache" % e)
   Key 20 not found in the cache

In addition to the above methods, the RCUCache object also has the following methods:

• clear() Remove all items from the cache.

• copy() Returns a shallow copy of the cache.

• items() Returns the dictionary's items ((key, value) pairs).

• popitem(last=True) The popitem() method for ordered dictionaries returns and removes a (key, value) pair. The pairs are returned in LIFO order if last is true or FIFO order if false.

• pop(key[, default]) If key is in the dictionary, remove it and return its value, else return default. If default is not given and key is not in the dictionary, a KeyError is raised.

• update([other]) Update the dictionary with the key/value pairs from other, overwriting existing keys. The maxsize is honored during an update.