def test_transition_events(storage):
"""It should call the appropriate functions on every state transition."""
class Listener(CircuitBreakerListener):
def __init__(self):
self.out = []
def state_change(self, breaker, old, new):
assert breaker
self.out.append((old.state, new.state))
listener = Listener()
breaker = CircuitBreaker(listeners=(listener, ), state_storage=storage)
assert CircuitBreakerState.CLOSED == breaker.current_state
breaker.open()
assert CircuitBreakerState.OPEN == breaker.current_state
breaker.half_open()
assert CircuitBreakerState.HALF_OPEN == breaker.current_state
breaker.close()
assert CircuitBreakerState.CLOSED == breaker.current_state
assert [(CircuitBreakerState.CLOSED, CircuitBreakerState.OPEN),
(CircuitBreakerState.OPEN, CircuitBreakerState.HALF_OPEN),
(CircuitBreakerState.HALF_OPEN, CircuitBreakerState.CLOSED)
] == listener.out
def test_close(storage):
"""It should allow the circuit to be closed manually."""
breaker = CircuitBreaker(fail_max=3, state_storage=storage)
breaker.open()
assert 0 == breaker.fail_counter
assert CircuitBreakerState.OPEN == breaker.current_state
breaker.close()
assert 0 == breaker.fail_counter
assert CircuitBreakerState.CLOSED == breaker.current_state
def test_half_open_thread_safety(self):
"""
it should allow only one trial call when the circuit is half-open.
"""
breaker = CircuitBreaker(fail_max=1,
timeout_duration=timedelta(seconds=0.01))
breaker.open()
sleep(0.01)
@breaker
def err():
raise DummyException()
def trigger_failure():
try:
err()
except DummyException:
pass
except CircuitBreakerError:
pass
class StateListener(CircuitBreakerListener):
def __init__(self):
self._count = 0
def before_call(self, breaker, func, *args, **kwargs):
sleep(0.00005)
def state_change(self, breaker, old, new):
if new.name == STATE_HALF_OPEN:
self._count += 1
state_listener = StateListener()
breaker.add_listener(state_listener)
self._start_threads(trigger_failure, 5)
self.assertEqual(1, state_listener._count)
