repoze.lru 0.5

A tiny LRU cache implementation and decorator

repoze.lru

repoze.lru is a LRU (least recently used) cache implementation. Keys and values that are not used frequently will be evicted from the cache faster than keys and values that are used frequently. It works under Python 2.5, Python 2.6, Python 2.7, and Python 3.2.

API

Creating an LRUCache object:

from repoze.lru import LRUCache
cache = LRUCache(100) # 100 max length

Retrieving from an LRUCache object:

cache.get('nonexisting', 'foo') # will return 'foo'
cache.get('nonexisting') # will return None
cache.get('existing') # will return the value for existing

Adding to an LRUCache object:

cache.put('key', 'value') # will add the key 'key' with the value 'value'

Clearing an LRUCache:

cache.clear()

Decorator

A lru_cache decorator exists. All values passed to the decorated function must be hashable. It does not support keyword arguments:

from repoze.lru import lru_cache

@lru_cache(500)
def expensive_function(*arg):
    pass

Each function decorated with the lru_cache decorator uses its own cache related to that function.

Changelog

After 0.5

• Bug: Remove potential race condition on lock in face of interrupts (Issue #10).

0.5 (2012-03-24)

• Feature: added a new “invalidate()” method to allow removal of items from the cache (issue #8).

• Bug: LRUCache.put() could take multiple seconds on large caches (Issue #7).

• Bug: LRUCache was not thread safe (Issue #6).

• Bug: LRUCache.clock would waste RAM (Issue #4).

• Bug: repeated pushing of an entry would remove other cache entries (Issue #3).

• Bug: LRUCache would evict entries even when not full (Issue #2).

0.4 (2011-09-04)

• Moved to GitHub (https://github.com/repoze/repoze.lru).

• Added Python 3.2 support.

• Python 2.4 no longer supported.

• Added tox.ini for easier testing.

0.3 (2009/06/16)

• Add a thread lock around clear logic.

0.2 (2009/06/15)

• Add a clear method.

0.1 (2009/06/14)

• Initial release.