Hash load balance to a sub set of nodes

lb_hash_subset.py

import collections
import random
from hash_ring import HashRing

from pprint import pprint

nodes = range(10)
nodes_dist = []

for i in range(len(nodes)):
    c = tuple(random.choice(nodes) for j in range(3))
    nodes_dist.append(c)
    
weights = dict()
for i in range(len(nodes)):
    weights[nodes_dist[i]] = 1
    
pprint(nodes_dist)
pprint(weights)

ring = HashRing(nodes_dist, weights)

for i in range(10):
    print random.choice(ring.get_node("test"))

Cool, after looking at hash_ring I think it uses the string representation of each nodes_dist entry to compute its key. So if you later add or remove a node from a group then its key could change and the list of sorted keys _sorted_keys could change. It may be more convenient to pass to HashRing a list of group names and keep a separate dict of group_name -> [nodes].

import collections
import random
from hash_ring import HashRing

from pprint import pprint

nodes = range(10)
groups_dist = []

groups_count = 10
for i in range(groups_count):
    groups_dist.append("group %d" % i)

group_nodes = dict()
for i in range(groups_count):
    group_nodes["group %d" % i] = [random.choice(nodes) for j in range(3)]
    
weights = dict()
for i in range(len(nodes)):
    weights[groups_dist[i]] = 1
    
pprint(groups_dist)
pprint(weights)

ring = HashRing(groups_dist, weights)

for i in range(10):
    print random.choice(group_nodes[ring.get_node("test")])