Hash ring

Tooz provides a consistent hash ring implementation. It can be used to map objects (represented via binary keys) to one or several nodes. When the node list changes, the rebalancing of objects across the ring is kept minimal.

from tooz import hashring

hashring = hashring.HashRing({'node1', 'node2', 'node3'})

# Returns set(['node2'])
nodes_for_foo = hashring[b'foo']

# Returns set(['node2', 'node3'])
nodes_for_foo_with_replicas = hashring.get_nodes(b'foo',
                                                 replicas=2)

# Returns set(['node1', 'node3'])
nodes_for_foo_with_replicas = hashring.get_nodes(b'foo',
                                                 replicas=2,
                                                 ignore_nodes={'node2'})