def test_with_remotes(self):
hosts = [Host(i, SimpleConvictionPolicy) for i in range(4)]
for h in hosts[:2]:
h.set_location_info("dc1", "rack1")
for h in hosts[2:]:
h.set_location_info("dc2", "rack1")
local_hosts = set(h for h in hosts if h.datacenter == "dc1")
remote_hosts = set(h for h in hosts if h.datacenter != "dc1")
# allow all of the remote hosts to be used
policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=2)
policy.populate(Mock(), hosts)
qplan = list(policy.make_query_plan())
self.assertEqual(set(qplan[:2]), local_hosts)
self.assertEqual(set(qplan[2:]), remote_hosts)
# allow only one of the remote hosts to be used
policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=1)
policy.populate(Mock(), hosts)
qplan = list(policy.make_query_plan())
self.assertEqual(set(qplan[:2]), local_hosts)
used_remotes = set(qplan[2:])
self.assertEqual(1, len(used_remotes))
self.assertIn(qplan[2], remote_hosts)
# allow no remote hosts to be used
policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=0)
policy.populate(Mock(), hosts)
qplan = list(policy.make_query_plan())
self.assertEqual(2, len(qplan))
self.assertEqual(local_hosts, set(qplan))
def test_no_nodes(self):
"""
Ensure query plan for an empty cluster will execute without errors
"""
policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=1)
policy.populate(None, [])
qplan = list(policy.make_query_plan())
self.assertEqual(qplan, [])
def test_no_remote(self):
hosts = []
for i in range(4):
h = Host(i, SimpleConvictionPolicy)
h.set_location_info("dc1", "rack1")
hosts.append(h)
policy = DCAwareRoundRobinPolicy("dc1")
policy.populate(None, hosts)
qplan = list(policy.make_query_plan())
self.assertEqual(sorted(qplan), sorted(hosts))
def test_status_updates(self):
hosts = [Host(i, SimpleConvictionPolicy) for i in range(4)]
for h in hosts[:2]:
h.set_location_info("dc1", "rack1")
for h in hosts[2:]:
h.set_location_info("dc2", "rack1")
policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=1)
policy.populate(Mock(), hosts)
policy.on_down(hosts[0])
policy.on_remove(hosts[2])
new_local_host = Host(4, SimpleConvictionPolicy)
new_local_host.set_location_info("dc1", "rack1")
policy.on_up(new_local_host)
new_remote_host = Host(5, SimpleConvictionPolicy)
new_remote_host.set_location_info("dc9000", "rack1")
policy.on_add(new_remote_host)
# we now have two local hosts and two remote hosts in separate dcs
qplan = list(policy.make_query_plan())
self.assertEqual(set(qplan[:2]), set([hosts[1], new_local_host]))
self.assertEqual(set(qplan[2:]), set([hosts[3], new_remote_host]))
# since we have hosts in dc9000, the distance shouldn't be IGNORED
self.assertEqual(policy.distance(new_remote_host), HostDistance.REMOTE)
policy.on_down(new_local_host)
policy.on_down(hosts[1])
qplan = list(policy.make_query_plan())
self.assertEqual(set(qplan), set([hosts[3], new_remote_host]))
policy.on_down(new_remote_host)
policy.on_down(hosts[3])
qplan = list(policy.make_query_plan())
self.assertEqual(qplan, [])
def test_no_live_nodes(self):
"""
Ensure query plan for a downed cluster will execute without errors
"""
hosts = []
for i in range(4):
h = Host(i, SimpleConvictionPolicy)
h.set_location_info("dc1", "rack1")
hosts.append(h)
policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=1)
policy.populate(Mock(), hosts)
for host in hosts:
policy.on_down(host)
qplan = list(policy.make_query_plan())
self.assertEqual(qplan, [])
def test_modification_during_generation(self):
hosts = [Host(i, SimpleConvictionPolicy) for i in range(4)]
for h in hosts[:2]:
h.set_location_info("dc1", "rack1")
for h in hosts[2:]:
h.set_location_info("dc2", "rack1")
policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=3)
policy.populate(Mock(), hosts)
# The general concept here is to change thee internal state of the
# policy during plan generation. In this case we use a grey-box
# approach that changes specific things during known phases of the
# generator.
new_host = Host(4, SimpleConvictionPolicy)
new_host.set_location_info("dc1", "rack1")
# new local before iteration
plan = policy.make_query_plan()
policy.on_up(new_host)
# local list is not bound yet, so we get to see that one
self.assertEqual(len(list(plan)), 3 + 2)
# remove local before iteration
plan = policy.make_query_plan()
policy.on_down(new_host)
# local list is not bound yet, so we don't see it
self.assertEqual(len(list(plan)), 2 + 2)
# new local after starting iteration
plan = policy.make_query_plan()
next(plan)
policy.on_up(new_host)
# local list was is bound, and one consumed, so we only see the other original
self.assertEqual(len(list(plan)), 1 + 2)
# remove local after traversing available
plan = policy.make_query_plan()
for _ in range(3):
next(plan)
policy.on_down(new_host)
# we should be past the local list
self.assertEqual(len(list(plan)), 0 + 2)
# REMOTES CHANGE
new_host.set_location_info("dc2", "rack1")
# new remote after traversing local, but not starting remote
plan = policy.make_query_plan()
for _ in range(2):
next(plan)
policy.on_up(new_host)
# list is updated before we get to it
self.assertEqual(len(list(plan)), 0 + 3)
# remove remote after traversing local, but not starting remote
plan = policy.make_query_plan()
for _ in range(2):
next(plan)
policy.on_down(new_host)
# list is updated before we get to it
self.assertEqual(len(list(plan)), 0 + 2)
# new remote after traversing local, and starting remote
plan = policy.make_query_plan()
for _ in range(3):
next(plan)
policy.on_up(new_host)
# slice is already made, and we've consumed one
self.assertEqual(len(list(plan)), 0 + 1)
# remove remote after traversing local, and starting remote
plan = policy.make_query_plan()
for _ in range(3):
next(plan)
policy.on_down(new_host)
# slice is created with all present, and we've consumed one
self.assertEqual(len(list(plan)), 0 + 2)
# local DC disappears after finishing it, but not starting remote
plan = policy.make_query_plan()
for _ in range(2):
next(plan)
policy.on_down(hosts[0])
policy.on_down(hosts[1])
# dict traversal starts as normal
self.assertEqual(len(list(plan)), 0 + 2)
policy.on_up(hosts[0])
policy.on_up(hosts[1])
# PYTHON-297 addresses the following cases, where DCs come and go
# during generation
# local DC disappears after finishing it, and starting remote
plan = policy.make_query_plan()
for _ in range(3):
next(plan)
policy.on_down(hosts[0])
policy.on_down(hosts[1])
# dict traversal has begun and consumed one
self.assertEqual(len(list(plan)), 0 + 1)
policy.on_up(hosts[0])
policy.on_up(hosts[1])
# remote DC disappears after finishing local, but not starting remote
plan = policy.make_query_plan()
for _ in range(2):
next(plan)
policy.on_down(hosts[2])
policy.on_down(hosts[3])
# nothing left
self.assertEqual(len(list(plan)), 0 + 0)
policy.on_up(hosts[2])
policy.on_up(hosts[3])
# remote DC disappears while traversing it
plan = policy.make_query_plan()
for _ in range(3):
next(plan)
policy.on_down(hosts[2])
policy.on_down(hosts[3])
# we continue with remainder of original list
self.assertEqual(len(list(plan)), 0 + 1)
policy.on_up(hosts[2])
policy.on_up(hosts[3])
another_host = Host(5, SimpleConvictionPolicy)
another_host.set_location_info("dc3", "rack1")
new_host.set_location_info("dc3", "rack1")
# new DC while traversing remote
plan = policy.make_query_plan()
for _ in range(3):
next(plan)
policy.on_up(new_host)
policy.on_up(another_host)
# we continue with remainder of original list
self.assertEqual(len(list(plan)), 0 + 1)
# remote DC disappears after finishing it
plan = policy.make_query_plan()
for _ in range(3):
next(plan)
last_host_in_this_dc = next(plan)
if last_host_in_this_dc in (new_host, another_host):
down_hosts = [new_host, another_host]
else:
down_hosts = hosts[2:]
for h in down_hosts:
policy.on_down(h)
# the last DC has two
self.assertEqual(len(list(plan)), 0 + 2)