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Fix TokenAwarePolicy to call child.make_query_plan once #634

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Fix TokenAwarePolicy to call child.make_query_plan once #634

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3481055
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Copilot Dec 27, 2025
507b252
Optimize TokenAwarePolicy to call child.make_query_plan only once
Copilot Dec 29, 2025
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10 changes: 6 additions & 4 deletions cassandra/policies.py
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Original file line number Diff line number Diff line change
Expand Up @@ -505,8 +505,12 @@ def make_query_plan(self, working_keyspace=None, query=None):
keyspace = query.keyspace if query and query.keyspace else working_keyspace

child = self._child_policy

# Call child.make_query_plan only once and convert to list for reuse
child_plan = list(child.make_query_plan(keyspace, query))

if query is None or query.routing_key is None or keyspace is None:
for host in child.make_query_plan(keyspace, query):
for host in child_plan:
yield host
return

Expand All @@ -517,8 +521,6 @@ def make_query_plan(self, working_keyspace=None, query=None):

if tablet is not None:
replicas_mapped = set(map(lambda r: r[0], tablet.replicas))
child_plan = child.make_query_plan(keyspace, query)

replicas = [host for host in child_plan if host.host_id in replicas_mapped]
else:
replicas = self._cluster_metadata.get_replicas(keyspace, query.routing_key)
Expand All @@ -535,7 +537,7 @@ def yield_in_order(hosts):
# yield replicas: local_rack, local, remote
yield from yield_in_order(replicas)
# yield rest of the cluster: local_rack, local, remote
yield from yield_in_order([host for host in child.make_query_plan(keyspace, query) if host not in replicas])
yield from yield_in_order([host for host in child_plan if host not in replicas])

def on_up(self, *args, **kwargs):
return self._child_policy.on_up(*args, **kwargs)
Expand Down
67 changes: 62 additions & 5 deletions tests/unit/test_policies.py
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Original file line number Diff line number Diff line change
Expand Up @@ -945,13 +945,70 @@ def _assert_shuffle(self, patched_shuffle, cluster, keyspace, routing_key):
else:
assert set(replicas) == set(qplan[:2])
assert hosts[:2] == qplan[2:]
if is_tablets:
child_policy.make_query_plan.assert_called_with(keyspace, query)
assert child_policy.make_query_plan.call_count == 2
else:
child_policy.make_query_plan.assert_called_once_with(keyspace, query)
# After optimization, child.make_query_plan should be called once for both tablets and vnodes
child_policy.make_query_plan.assert_called_once_with(keyspace, query)
assert patched_shuffle.call_count == 1

def test_child_make_query_plan_called_once(self):
"""
Test to validate that child.make_query_plan is called only once
in all scenarios (with/without tablets, with/without routing key)

@test_category policy
"""
# Test with vnodes (no tablets)
hosts = [Host(DefaultEndPoint(str(i)), SimpleConvictionPolicy) for i in range(4)]
for host in hosts:
host.set_up()

cluster = Mock(spec=Cluster)
cluster.metadata = Mock(spec=Metadata)
cluster.metadata._tablets = Mock(spec=Tablets)
cluster.metadata._tablets.table_has_tablets.return_value = False
replicas = hosts[2:]
cluster.metadata.get_replicas.return_value = replicas

child_policy = Mock()
child_policy.make_query_plan.return_value = hosts
child_policy.distance.return_value = HostDistance.LOCAL

policy = TokenAwarePolicy(child_policy)
policy.populate(cluster, hosts)

# Test case 1: With routing key and keyspace (should call once)
child_policy.reset_mock()
keyspace = 'keyspace'
routing_key = 'routing_key'
query = Statement(routing_key=routing_key, keyspace=keyspace)
qplan = list(policy.make_query_plan(keyspace, query))
child_policy.make_query_plan.assert_called_once_with(keyspace, query)

# Test case 2: Without routing key (should call once)
child_policy.reset_mock()
query = Statement(routing_key=None, keyspace=keyspace)
qplan = list(policy.make_query_plan(keyspace, query))
child_policy.make_query_plan.assert_called_once_with(keyspace, query)

# Test case 3: Without keyspace (should call once)
child_policy.reset_mock()
query = Statement(routing_key=routing_key, keyspace=None)
qplan = list(policy.make_query_plan(None, query))
child_policy.make_query_plan.assert_called_once_with(None, query)

# Test case 4: With tablets (should call once)
cluster.metadata._tablets.table_has_tablets.return_value = True
tablet = Mock(spec=Tablet)
tablet.replicas = [(hosts[0].host_id, None), (hosts[1].host_id, None)]
cluster.metadata._tablets.get_tablet_for_key.return_value = tablet
cluster.metadata.token_map = Mock()
cluster.metadata.token_map.token_class = Mock()
cluster.metadata.token_map.token_class.from_key.return_value = 'token'

child_policy.reset_mock()
query = Statement(routing_key=routing_key, keyspace=keyspace, table='test_table')
qplan = list(policy.make_query_plan(keyspace, query))
child_policy.make_query_plan.assert_called_once_with(keyspace, query)


class ConvictionPolicyTest(unittest.TestCase):
def test_not_implemented(self):
Expand Down