def test_hash_ring(self):
num_nodes = 10
num_keys = 1000
nodes = [str(x) for x in range(num_nodes)]
hr = coordination.HashRing(nodes)
buckets = [0] * num_nodes
assignments = [-1] * num_keys
for k in range(num_keys):
n = int(hr.get_node(str(k)))
self.assertLessEqual(0, n)
self.assertLessEqual(n, num_nodes)
buckets[n] += 1
assignments[k] = n
# at least something in each bucket
self.assertTrue(all((c > 0 for c in buckets)))
# approximately even distribution
diff = max(buckets) - min(buckets)
self.assertLess(diff, 0.3 * (num_keys / num_nodes))
# consistency
num_nodes += 1
nodes.append(str(num_nodes + 1))
hr = coordination.HashRing(nodes)
for k in range(num_keys):
n = int(hr.get_node(str(k)))
assignments[k] -= n
reassigned = len([c for c in assignments if c != 0])
self.assertLess(reassigned, num_keys / num_nodes)
def test_partitioning(self):
all_resources = ['resource_%s' % i for i in range(1000)]
agents = ['agent_%s' % i for i in range(10)]
expected_resources = [list() for _ in range(len(agents))]
hr = coordination.HashRing(agents)
for r in all_resources:
key = agents.index(hr.get_node(r))
expected_resources[key].append(r)
agents_kwargs = []
for i, agent in enumerate(agents):
agents_kwargs.append(dict(agent_id=agent,
group_id='group',
all_resources=all_resources,
expected_resources=expected_resources[i]))
self._usage_simulation(*agents_kwargs)