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from time import sleep |
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from mock.mock import patch, Mock |
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from pytest import raises |
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from circuitbreaker import CircuitBreaker, CircuitBreakerError, \ |
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CircuitBreakerMonitor, STATE_CLOSED, STATE_HALF_OPEN, STATE_OPEN |
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def pseudo_remote_call(): |
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return True |
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@CircuitBreaker() |
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def circuit_success(): |
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return pseudo_remote_call() |
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@CircuitBreaker(failure_threshold=1, name="circuit_failure") |
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def circuit_failure(): |
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raise ConnectionError() |
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@CircuitBreaker(failure_threshold=1, name="threshold_1") |
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def circuit_threshold_1(): |
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return pseudo_remote_call() |
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@CircuitBreaker(failure_threshold=2, recover_timeout=1, name="threshold_2") |
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def circuit_threshold_2_timeout_1(): |
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return pseudo_remote_call() |
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@CircuitBreaker(failure_threshold=3, recover_timeout=1, name="threshold_3") |
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def circuit_threshold_3_timeout_1(): |
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return pseudo_remote_call() |
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def test_circuit_pass_through(): |
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assert circuit_success() is True |
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def test_circuitbreaker_monitor(): |
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assert CircuitBreakerMonitor.all_closed() is True |
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assert len(list(CircuitBreakerMonitor.get_circuits())) == 5 |
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assert len(list(CircuitBreakerMonitor.get_closed())) == 5 |
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assert len(list(CircuitBreakerMonitor.get_open())) == 0 |
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with raises(ConnectionError): |
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circuit_failure() |
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assert CircuitBreakerMonitor.all_closed() is False |
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assert len(list(CircuitBreakerMonitor.get_circuits())) == 5 |
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assert len(list(CircuitBreakerMonitor.get_closed())) == 4 |
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assert len(list(CircuitBreakerMonitor.get_open())) == 1 |
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@patch('test_functional.pseudo_remote_call', return_value=True) |
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def test_threshold_hit_prevents_consequent_calls(mock_remote: Mock): |
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mock_remote.side_effect = ConnectionError('Connection refused') |
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circuitbreaker = CircuitBreakerMonitor.get('threshold_1') |
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assert circuitbreaker.closed |
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with raises(ConnectionError): |
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circuit_threshold_1() |
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assert circuitbreaker.opened |
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with raises(CircuitBreakerError): |
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circuit_threshold_1() |
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mock_remote.assert_called_once() |
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@patch('test_functional.pseudo_remote_call', return_value=True) |
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def test_circuitbreaker_recover_half_open(mock_remote: Mock): |
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circuitbreaker = CircuitBreakerMonitor.get('threshold_3') |
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# initial state: closed |
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assert circuitbreaker.closed |
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assert circuitbreaker.state == STATE_CLOSED |
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# no exception -> success |
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assert circuit_threshold_3_timeout_1() |
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# from now all subsequent calls will fail |
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mock_remote.side_effect = ConnectionError('Connection refused') |
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# 1. failed call -> original exception |
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with raises(ConnectionError): |
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circuit_threshold_3_timeout_1() |
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assert circuitbreaker.closed |
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assert circuitbreaker.failure_count == 1 |
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# 2. failed call -> original exception |
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with raises(ConnectionError): |
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circuit_threshold_3_timeout_1() |
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assert circuitbreaker.closed |
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assert circuitbreaker.failure_count == 2 |
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# 3. failed call -> original exception |
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with raises(ConnectionError): |
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circuit_threshold_3_timeout_1() |
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# Circuit breaker opens, threshold has been reached |
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assert circuitbreaker.opened |
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assert circuitbreaker.state == STATE_OPEN |
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assert circuitbreaker.failure_count == 3 |
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assert 0 < circuitbreaker.open_remaining <= 1 |
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# 4. failed call -> not passed to function -> CircuitBreakerError |
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with raises(CircuitBreakerError): |
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circuit_threshold_3_timeout_1() |
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assert circuitbreaker.opened |
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assert circuitbreaker.failure_count == 3 |
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assert 0 < circuitbreaker.open_remaining <= 1 |
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# 5. failed call -> not passed to function -> CircuitBreakerError |
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with raises(CircuitBreakerError): |
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circuit_threshold_3_timeout_1() |
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assert circuitbreaker.opened |
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assert circuitbreaker.failure_count == 3 |
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assert 0 < circuitbreaker.open_remaining <= 1 |
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# wait for 1 second (recover timeout) |
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sleep(1) |
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# circuit half-open -> next call will be passed through |
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assert circuitbreaker.closed |
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assert circuitbreaker.open_remaining < 0 |
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assert circuitbreaker.state == STATE_HALF_OPEN |
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# State half-open -> function is executed -> original exception |
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with raises(ConnectionError): |
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circuit_threshold_3_timeout_1() |
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assert circuitbreaker.opened |
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assert circuitbreaker.failure_count == 4 |
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assert 0 < circuitbreaker.open_remaining <= 1 |
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# State open > not passed to function -> CircuitBreakerError |
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with raises(CircuitBreakerError): |
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circuit_threshold_3_timeout_1() |
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@patch('test_functional.pseudo_remote_call', return_value=True) |
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def test_circuitbreaker_reopens_after_successful_call(mock_remote: Mock): |
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circuitbreaker = CircuitBreakerMonitor.get('threshold_2') |
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assert str(circuitbreaker) == 'threshold_2' |
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# initial state: closed |
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assert circuitbreaker.closed |
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assert circuitbreaker.state == STATE_CLOSED |
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assert circuitbreaker.failure_count == 0 |
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# successful call -> no exception |
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assert circuit_threshold_2_timeout_1() |
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# from now all subsequent calls will fail |
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mock_remote.side_effect = ConnectionError('Connection refused') |
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# 1. failed call -> original exception |
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with raises(ConnectionError): |
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circuit_threshold_2_timeout_1() |
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assert circuitbreaker.closed |
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assert circuitbreaker.failure_count == 1 |
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# 2. failed call -> original exception |
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with raises(ConnectionError): |
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circuit_threshold_2_timeout_1() |
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# Circuit breaker opens, threshold has been reached |
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assert circuitbreaker.opened |
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assert circuitbreaker.state == STATE_OPEN |
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assert circuitbreaker.failure_count == 2 |
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assert 0 < circuitbreaker.open_remaining <= 1 |
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# 4. failed call -> not passed to function -> CircuitBreakerError |
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with raises(CircuitBreakerError): |
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circuit_threshold_2_timeout_1() |
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assert circuitbreaker.opened |
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assert circuitbreaker.failure_count == 2 |
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assert 0 < circuitbreaker.open_remaining <= 1 |
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# from now all subsequent calls will succeed |
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mock_remote.side_effect = None |
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# but recover timeout has not been reached -> still open |
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# 5. failed call -> not passed to function -> CircuitBreakerError |
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with raises(CircuitBreakerError): |
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circuit_threshold_2_timeout_1() |
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assert circuitbreaker.opened |
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assert circuitbreaker.failure_count == 2 |
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assert 0 < circuitbreaker.open_remaining <= 1 |
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# wait for 1 second (recover timeout) |
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sleep(1) |
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# circuit half-open -> next call will be passed through |
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assert circuitbreaker.closed |
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assert circuitbreaker.failure_count == 2 |
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assert circuitbreaker.open_remaining < 0 |
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assert circuitbreaker.state == STATE_HALF_OPEN |
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# successful call |
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assert circuit_threshold_2_timeout_1() |
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# circuit closed and reset'ed |
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assert circuitbreaker.closed |
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assert circuitbreaker.state == STATE_CLOSED |
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assert circuitbreaker.failure_count == 0 |
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# some another successful calls |
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assert circuit_threshold_2_timeout_1() |
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assert circuit_threshold_2_timeout_1() |
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assert circuit_threshold_2_timeout_1() |
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# @CircuitBreaker(failure_threshold=2, recover_timeout=4) |
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# def external_call(call_id): |
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# if call_id in (2, 3, 6, 7, 10, 12, 15): |
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# raise ConnectionError('Connection refused') |
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# return 'SUCCESS' |
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# |
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# for i in range(0, 20): |
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# try: |
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# print('CALL: %d' % i) |
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# print(' ## %s ' % external_call(i)) |
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# except Exception as e: |
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# print(' \__ %s ' % e) |
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# |
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# sleep(0.5) |
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