hash_ring 0.95

About hash_ring

Implements consistent hashing that can be used when the number of server nodes can increase or decrease (like in memcached).

Consistent hashing is a scheme that provides a hash table functionality in a way that the adding or removing of one slot does not significantly change the mapping of keys to slots.

More about hash_ring can be read in a blog post (that explains the idea in greater details):

• Consistent hashing implemented simply in python <http://amix.dk/blog/viewEntry/19367>

More information about consistent hashing can be read in these articles:

• Web Caching with Consistent Hashing <http://www8.org/w8-papers/2a-webserver/caching/paper2.html>

• Consistent hashing and random trees <http://citeseerx.ist.psu.edu/legacymapper?did=38148>

Example

Basic example of usage (for managing memcached instances):

memcache_servers = ['192.168.0.246:11212',
                    '192.168.0.247:11212',
                    '192.168.0.249:11212']

ring = HashRing(memcache_servers)
server = ring.get_node('my_key')

The code should be clean and simple. Feel free to concat the author if you detect bugs.