def test_fallback_logic() -> None:
state.set_config("use_fallback_host_in_native_connection_pool", 1)
network_failure_connection = mock.Mock()
network_failure_connection.execute.side_effect = EOFError()
verification_connection = mock.Mock()
verification_connection.execute.return_value = []
pool = ClickhousePool(CLUSTER_HOST, CLUSTER_PORT, "test", "test",
TEST_DB_NAME)
# The execute method will try to reuse a single slot in the connection
# pool but reestablish new connections with _create_conn if a connection
# fails with a network-related error. It may be cleaner to move connection
# negotation/establishment into another class for separation of concerns.
with mock.patch.object(pool,
"_create_conn",
lambda x, y=False: network_failure_connection):
pool.pool = queue.LifoQueue(1)
pool.pool.put(network_failure_connection, block=False)
pool.fallback_pool = queue.LifoQueue(1)
pool.fallback_pool.put(verification_connection, block=False)
pool.execute("SELECT something")
assert (network_failure_connection.execute.call_count == 3
), "Expected three (failed) attempts with main connection pool"
assert (
verification_connection.execute.call_count == 1
), "Expected one (successful) attempt with fallback connection pool"
def test_concurrency_limit() -> None:
connection = mock.Mock()
connection.execute.side_effect = TestError("some error")
state.set_config("simultaneous_queries_sleep_seconds", 0.5)
pool = ClickhousePool("host", 100, "test", "test", "test")
pool.pool = queue.LifoQueue(1)
pool.pool.put(connection, block=False)
with pytest.raises(ClickhouseError):
pool.execute("SELECT something")
connection.execute.assert_called_once()
connection.reset_mock(side_effect=True)
connection.execute.side_effect = TestConcurrentError("some error")
with pytest.raises(ClickhouseError):
pool.execute("SELECT something")
assert connection.execute.call_count == 2, "Expected two attempts"
def test_robust_concurrency_limit() -> None:
connection = mock.Mock()
connection.execute.side_effect = ClickhouseError("some error",
extra_data={"code": 1})
pool = ClickhousePool("host", 100, "test", "test", "test")
pool.pool = queue.LifoQueue(1)
pool.pool.put(connection, block=False)
with pytest.raises(ClickhouseError):
pool.execute_robust("SELECT something")
connection.execute.assert_called_once()
connection.reset_mock(side_effect=True)
connection.execute.side_effect = ClickhouseError(
"some error",
code=errors.ErrorCodes.TOO_MANY_SIMULTANEOUS_QUERIES,
)
with pytest.raises(ClickhouseError):
pool.execute_robust("SELECT something")
assert connection.execute.call_count == 3, "Expected three attempts"