public void testTripCircuit()
{
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter();
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
metrics.MarkSuccess(1000);
metrics.MarkSuccess(1000);
metrics.MarkSuccess(1000);
metrics.MarkSuccess(1000);
// this should still allow requests as everything has been successful
Assert.True(cb.AllowRequest);
Assert.False(cb.IsOpen());
// fail
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
// everything has failed in the test window so we should return false now
Assert.False(cb.AllowRequest);
Assert.True(cb.IsOpen());
}
public void testSingleTestOnOpenCircuitAfterTimeWindow()
{
int sleepWindow = 200;
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter().WithCircuitBreakerSleepWindowInMilliseconds(sleepWindow);
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
// fail
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
// everything has failed in the test window so we should return false now
Assert.False(cb.AllowRequest);
Assert.True(cb.IsOpen());
// wait for sleepWindow to pass
clock.Increment(sleepWindow + 50);
// we should now allow 1 request
Assert.True(cb.AllowRequest);
// but the circuit should still be open
Assert.True(cb.IsOpen());
// and further requests are still blocked
Assert.False(cb.AllowRequest);
}
public void testTripCircuitOnTimeoutsAboveThreshold()
{
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter();
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
// this should start as allowing requests
Assert.True(cb.AllowRequest);
Assert.False(cb.IsOpen());
// success with high latency
metrics.MarkSuccess(400);
metrics.MarkSuccess(400);
metrics.MarkTimeout(10);
metrics.MarkSuccess(400);
metrics.MarkTimeout(10);
metrics.MarkTimeout(10);
metrics.MarkSuccess(400);
metrics.MarkTimeout(10);
metrics.MarkTimeout(10);
// this should trip the circuit as the error percentage is above the threshold
Assert.False(cb.AllowRequest);
Assert.True(cb.IsOpen());
}
public void testCircuitDoesNotTripOnFailuresBelowThreshold()
{
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter();
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
// this should start as allowing requests
Assert.True(cb.AllowRequest);
Assert.False(cb.IsOpen());
// success with high latency
metrics.MarkSuccess(400);
metrics.MarkSuccess(400);
metrics.MarkFailure(10);
metrics.MarkSuccess(400);
metrics.MarkSuccess(40);
metrics.MarkSuccess(400);
metrics.MarkFailure(10);
metrics.MarkFailure(10);
// this should remain open as the failure threshold is below the percentage limit
Assert.True(cb.AllowRequest);
Assert.False(cb.IsOpen());
}
public void testCircuitClosedAfterSuccessAndClearsStatisticalWindow()
{
int statisticalWindow = 200;
int sleepWindow = 10; // this is set very low so that returning from a retry still ends up having data in the buckets for the statisticalWindow
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter()
.WithCircuitBreakerSleepWindowInMilliseconds(sleepWindow)
.WithMetricsRollingStatisticalWindowInMilliseconds(statisticalWindow);
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
// fail
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
// everything has failed in the test window so we should return false now
Assert.False(cb.AllowRequest);
Assert.True(cb.IsOpen());
// wait for sleepWindow to pass
clock.Increment(sleepWindow + 50);
// we should now allow 1 request
Assert.True(cb.AllowRequest);
// but the circuit should still be open
Assert.True(cb.IsOpen());
// and further requests are still blocked
Assert.False(cb.AllowRequest);
// the 'singleTest' succeeds so should cause the circuit to be closed
metrics.MarkSuccess(500);
cb.MarkSuccess();
// all requests should be open again
Assert.True(cb.AllowRequest);
Assert.True(cb.AllowRequest);
Assert.True(cb.AllowRequest);
// and the circuit should be closed again
Assert.False(cb.IsOpen());
}
public void testTripCircuitOnTimeouts()
{
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter();
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
// this should start as allowing requests
Assert.True(cb.AllowRequest);
Assert.False(cb.IsOpen());
// timeouts
metrics.MarkTimeout(2000);
metrics.MarkTimeout(2000);
metrics.MarkTimeout(2000);
metrics.MarkTimeout(2000);
// everything has been a timeout so we should not allow any requests
Assert.False(cb.AllowRequest);
Assert.True(cb.IsOpen());
}
public void testLowVolumeDoesNotTripCircuit()
{
int sleepWindow = 200;
int lowVolume = 5;
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter().WithCircuitBreakerSleepWindowInMilliseconds(sleepWindow).WithCircuitBreakerRequestVolumeThreshold(lowVolume);
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
// fail
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
// even though it has all failed we won't trip the circuit because the volume is low
Assert.True(cb.AllowRequest);
Assert.False(cb.IsOpen());
}
public void testMultipleTimeWindowRetriesBeforeClosingCircuit()
{
int sleepWindow = 200;
var properties = CommandPropertiesTest.GetUnitTestPropertiesSetter().WithCircuitBreakerSleepWindowInMilliseconds(sleepWindow);
var clock = new MockedClock();
CommandMetrics metrics = getMetrics(properties, clock);
ICircuitBreaker cb = getCircuitBreaker("KEY_ONE", "OWNER_TWO", metrics, properties, clock);
// fail
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
metrics.MarkFailure(1000);
// everything has failed in the test window so we should return false now
Assert.False(cb.AllowRequest);
Assert.True(cb.IsOpen());
// wait for sleepWindow to pass
clock.Increment(sleepWindow + 50);
// we should now allow 1 request
Assert.True(cb.AllowRequest);
// but the circuit should still be open
Assert.True(cb.IsOpen());
// and further requests are still blocked
Assert.False(cb.AllowRequest);
// the 'singleTest' fails so it should go back to Sleep and not allow any requests again until another 'singleTest' after the Sleep
metrics.MarkFailure(1000);
Assert.False(cb.AllowRequest);
Assert.False(cb.AllowRequest);
Assert.False(cb.AllowRequest);
// wait for sleepWindow to pass
clock.Increment(sleepWindow + 50);
// we should now allow 1 request
Assert.True(cb.AllowRequest);
// but the circuit should still be open
Assert.True(cb.IsOpen());
// and further requests are still blocked
Assert.False(cb.AllowRequest);
// the 'singleTest' fails again so it should go back to Sleep and not allow any requests again until another 'singleTest' after the Sleep
metrics.MarkFailure(1000);
Assert.False(cb.AllowRequest);
Assert.False(cb.AllowRequest);
Assert.False(cb.AllowRequest);
// wait for sleepWindow to pass
clock.Increment(sleepWindow + 50);
// we should now allow 1 request
Assert.True(cb.AllowRequest);
// but the circuit should still be open
Assert.True(cb.IsOpen());
// and further requests are still blocked
Assert.False(cb.AllowRequest);
// now it finally succeeds
metrics.MarkSuccess(200);
cb.MarkSuccess();
// all requests should be open again
Assert.True(cb.AllowRequest);
Assert.True(cb.AllowRequest);
Assert.True(cb.AllowRequest);
// and the circuit should be closed again
Assert.False(cb.IsOpen());
}
