def test_rebalance_stability_join(self):
num_services = 10
num_nodes = 10000
# Adding 1 service to a set of N should move 1/(N+1) of all nodes
# Eg, for a cluster of 10 nodes, adding one should move 1/11, or 9%
# We allow for 1/N to allow for rounding in tests.
redistribution_factor = 1.0 / num_services
nodes = [str(x) for x in range(num_nodes)]
services = [str(x) for x in range(num_services)]
new_services = services + ['new']
delta = self._compare_rings(
nodes, services, hash_ring.HashRing(services),
new_services, hash_ring.HashRing(new_services))
self.assertLess(len(delta), num_nodes * redistribution_factor)
def test_rebalance_stability_leave(self):
num_services = 10
num_nodes = 10000
# Removing 1 service from a set of N should move 1/(N) of all nodes
# Eg, for a cluster of 10 nodes, removing one should move 1/10, or 10%
# We allow for 1/(N-1) to allow for rounding in tests.
redistribution_factor = 1.0 / (num_services - 1)
nodes = [str(x) for x in range(num_nodes)]
services = [str(x) for x in range(num_services)]
new_services = services[:]
new_services.pop()
delta = self._compare_rings(
nodes, services, hash_ring.HashRing(services),
new_services, hash_ring.HashRing(new_services))
self.assertLess(len(delta), num_nodes * redistribution_factor)
def test_distribution_one_replica(self):
hosts = ['foo', 'bar', 'baz']
ring = hash_ring.HashRing(hosts)
fake_1_hosts = ring.get_hosts('fake')
fake_2_hosts = ring.get_hosts('fake-again')
# We should have one hosts for each thing
self.assertThat(fake_1_hosts, matchers.HasLength(1))
self.assertThat(fake_2_hosts, matchers.HasLength(1))
# And they must not be the same answers even on this simple data.
self.assertNotEqual(fake_1_hosts, fake_2_hosts)
def test__hash2int_returns_int(self, mock_md5):
r1 = 32 * 'a'
r2 = 32 * 'b'
# 2**PARTITION_EXPONENT calls to md5.update per host
# PARTITION_EXPONENT is currently always 5, so 32 calls each here
mock_md5.return_value.hexdigest.side_effect = [r1] * 32 + [r2] * 32
hosts = ['foo', 'bar']
ring = hash_ring.HashRing(hosts)
self.assertIn(int(r1, 16), ring._host_hashes)
self.assertIn(int(r2, 16), ring._host_hashes)
def test_ignore_hosts(self):
hosts = ['foo', 'bar', 'baz']
ring = hash_ring.HashRing(hosts)
equals_bar_or_baz = matchers.MatchesAny(
matchers.Equals(['bar']),
matchers.Equals(['baz']))
self.assertThat(
ring.get_hosts('fake', ignore_hosts=['foo']),
equals_bar_or_baz)
self.assertThat(
ring.get_hosts('fake', ignore_hosts=['foo', 'bar']),
equals_bar_or_baz)
self.assertEqual([], ring.get_hosts('fake', ignore_hosts=hosts))
def test_create_ring(self):
hosts = ['foo', 'bar']
ring = hash_ring.HashRing(hosts)
self.assertEqual(set(hosts), ring.hosts)
self.assertEqual(1, ring.replicas)
self.assertEqual(2 ** 5 * 2, len(ring._partitions))
def test_get_hosts_invalid_data(self):
hosts = ['foo', 'bar']
ring = hash_ring.HashRing(hosts)
self.assertRaises(exception.Invalid,
ring.get_hosts,
None)
def test_ignore_non_existent_host(self):
hosts = ['foo', 'bar']
ring = hash_ring.HashRing(hosts)
self.assertEqual(['foo'], ring.get_hosts('fake',
ignore_hosts=['baz']))