Python policies.DCAwareRoundRobinPolicy类代码示例

    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_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_default_dc(self):
        host_local = Host(1, SimpleConvictionPolicy, 'local')
        host_remote = Host(2, SimpleConvictionPolicy, 'remote')
        host_none = Host(1, SimpleConvictionPolicy)

        # contact point is '1'
        cluster = Mock(contact_points=[1])

        # contact DC first
        policy = DCAwareRoundRobinPolicy()
        policy.populate(cluster, [host_none])
        self.assertFalse(policy.local_dc)
        policy.on_add(host_local)
        policy.on_add(host_remote)
        self.assertNotEqual(policy.local_dc, host_remote.datacenter)
        self.assertEqual(policy.local_dc, host_local.datacenter)

        # contact DC second
        policy = DCAwareRoundRobinPolicy()
        policy.populate(cluster, [host_none])
        self.assertFalse(policy.local_dc)
        policy.on_add(host_remote)
        policy.on_add(host_local)
        self.assertNotEqual(policy.local_dc, host_remote.datacenter)
        self.assertEqual(policy.local_dc, host_local.datacenter)

        # no DC
        policy = DCAwareRoundRobinPolicy()
        policy.populate(cluster, [host_none])
        self.assertFalse(policy.local_dc)
        policy.on_add(host_none)
        self.assertFalse(policy.local_dc)

        # only other DC
        policy = DCAwareRoundRobinPolicy()
        policy.populate(cluster, [host_none])
        self.assertFalse(policy.local_dc)
        policy.on_add(host_remote)
        self.assertFalse(policy.local_dc)

    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
#.........这里部分代码省略.........

    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_get_distance(self):
        policy = DCAwareRoundRobinPolicy("dc1", used_hosts_per_remote_dc=0)
        host = Host("ip1", SimpleConvictionPolicy)
        host.set_location_info("dc1", "rack1")
        policy.populate(Mock(), [host])

        self.assertEqual(policy.distance(host), HostDistance.LOCAL)

        # used_hosts_per_remote_dc is set to 0, so ignore it
        remote_host = Host("ip2", SimpleConvictionPolicy)
        remote_host.set_location_info("dc2", "rack1")
        self.assertEqual(policy.distance(remote_host), HostDistance.IGNORED)

        # dc2 isn't registered in the policy's live_hosts dict
        policy.used_hosts_per_remote_dc = 1
        self.assertEqual(policy.distance(remote_host), HostDistance.IGNORED)

        # make sure the policy has both dcs registered
        policy.populate(Mock(), [host, remote_host])
        self.assertEqual(policy.distance(remote_host), HostDistance.REMOTE)

        # since used_hosts_per_remote_dc is set to 1, only the first
        # remote host in dc2 will be REMOTE, the rest are IGNORED
        second_remote_host = Host("ip3", SimpleConvictionPolicy)
        second_remote_host.set_location_info("dc2", "rack1")
        policy.populate(Mock(), [host, remote_host, second_remote_host])
        distances = set([policy.distance(remote_host), policy.distance(second_remote_host)])
        self.assertEqual(distances, set([HostDistance.REMOTE, HostDistance.IGNORED]))

    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))