public void IsAllowing_WhenBothForcePropertiesSet_Rejects()
{
// Arrange
// Most property values don't matter, IsAllowing() should reject before it tries to use them.
var manualClock = new ManualTestClock();
var mockMetrics = new Mock <ICommandMetrics>();
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
var mockEvents = new Mock <IMetricEvents>();
var mockConfig = new Mock <IFailurePercentageCircuitBreakerConfig>();
mockConfig.Setup(m => m.GetMinimumOperations(It.IsAny <GroupKey>())).Returns(1);
mockConfig.Setup(m => m.GetThresholdPercentage(It.IsAny <GroupKey>())).Returns(1);
mockConfig.Setup(m => m.GetTrippedDurationMillis(It.IsAny <GroupKey>())).Returns(30000);
mockConfig.Setup(m => m.GetForceTripped(It.IsAny <GroupKey>())).Returns(true); // The config we're testing here.
mockConfig.Setup(m => m.GetForceFixed(It.IsAny <GroupKey>())).Returns(true); // The config we're testing here.
var breaker = new FailurePercentageCircuitBreaker(AnyKey, manualClock, mockMetrics.Object, mockEvents.Object, mockConfig.Object, new DefaultMjolnirLogFactory());
// Act / Assert
Assert.False(breaker.IsAllowing());
}
public void ManualTestClock_GetMillisecondTimestamp_UpdatesAfterAddingMillis()
{
var clock = new ManualTestClock();
clock.AddMilliseconds(20);
Assert.Equal(20, clock.GetMillisecondTimestamp());
}
public void IsAllowing_AfterSuccessfulSingleTest_FixesBreaker()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(11000);
breaker.IsAllowing(); // Send the single test.
clock.AddMilliseconds(500); // Pretend the test operation took a bit (not really necessary here).
breaker.MarkSuccess(0); // The single test transaction marks a success.
// Metrics should be reset.
mockMetrics.Verify(m => m.Reset(), Times.Once);
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
// Should be fixed now.
// Test IsAllowing() twice to make sure it's not just the single test we're allowing.
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
public void ManualTestClock_GetMillisecondTimestamp_DoesntAdvanceAutomatically()
{
var clock = new ManualTestClock();
Thread.Sleep(10);
Assert.Equal(0, clock.GetMillisecondTimestamp());
}
public void MarkSuccess_ImmediatelyAfterTrippingButStartedBeforeTripped_DoesntImmediatelyFix()
{
// 1. Breaker is near tripping.
// 2. Operation A and B are Allowed and begin work.
// 3. Before Operation A completes
// a. Operation B has an error and updates metrics.
// b. Operation C calls IsAllowing(), which trips breaker.
// 4. Operation A completes successfully and calls MarkSuccess().
// 5. Since breaker is tripped but we haven't hit our wait duration yet,
// MarkSuccess() should result in the the breaker remaining tripped.
// Arrange
var manualClock = new ManualTestClock();
var mockMetrics = new Mock <ICommandMetrics>();
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(2, 100)); // 2 ops, 100% failing.
var mockEvents = new Mock <IMetricEvents>();
var mockConfig = new Mock <IFailurePercentageCircuitBreakerConfig>();
mockConfig.SetupSequence(m => m.GetMinimumOperations(It.IsAny <GroupKey>()))
.Returns(5) // First access should be > 1 so that the breaker doesn't trip.
.Returns(1); // Second access should be 1, so that we trip the breaker because we have the minimum met.
mockConfig.Setup(m => m.GetThresholdPercentage(It.IsAny <GroupKey>())).Returns(1);
mockConfig.Setup(m => m.GetTrippedDurationMillis(It.IsAny <GroupKey>())).Returns(30000);
mockConfig.Setup(m => m.GetForceTripped(It.IsAny <GroupKey>())).Returns(false);
mockConfig.Setup(m => m.GetForceFixed(It.IsAny <GroupKey>())).Returns(false);
// 5 ops, 1% failure required to break.
var breaker = new FailurePercentageCircuitBreaker(AnyKey, manualClock, mockMetrics.Object, mockEvents.Object, mockConfig.Object, new DefaultMjolnirLogFactory());
// Act / Assert
// #2. Operation A is allowed and begins.
Assert.True(breaker.IsAllowing()); // Haven't hit the 1-operation threshold yet, should be allowed.
// #3a. Operation B errors. This is easier to simulate by changing the breaker's trip
// conditions. The sequenced Mock (above) has the second MinimumOperations returning
// 1, which would now mean we have enough operations to trip (where we didn't before).
// #3b. Breaker exceeds metrics thresholds, Operation C tries to IsAllowing() and trips breaker.
Assert.False(breaker.IsAllowing());
// #4. Operation A completes successfully.
// Breaker's internal _lastTrippedTimestamp should be equal to zero (current clock time).
// Since we say the transaction took 100ms, that'll be before the breaker tripped, and should
// be ignored.
breaker.MarkSuccess(100);
// #5. Make sure we're still tripped and we didn't reset the metrics.
Assert.False(breaker.IsAllowing());
mockMetrics.Verify(m => m.Reset(), Times.Never);
}
public void MarkSuccess_ForLongRunningSingleTest_FixesBreaker()
{
// Since we use the elapsed time in MarkSuccess(), address the following situation:
// 1. Breaker trips
// 2. Window passes
// 3. Single test is allowed
// 4. Single test takes a long time (say, > 2 windows) to complete (even though it started after we tripped).
// Verify that:
// - No other requests are allowed while the single test is waiting.
// - The single test, if successful, fixes the breaker.
// This is somewhat unlikely since we probably wont have command timeouts
// that'd allow this. But worth verifying.
// Arrange
var manualClock = new ManualTestClock();
var mockMetrics = new Mock <ICommandMetrics>();
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(2, 100)); // 2 ops, 100% failing.
var mockEvents = new Mock <IMetricEvents>();
const long trippedDurationMillis = 30000;
var mockConfig = new Mock <IFailurePercentageCircuitBreakerConfig>();
mockConfig.Setup(m => m.GetMinimumOperations(It.IsAny <GroupKey>())).Returns(1);
mockConfig.Setup(m => m.GetThresholdPercentage(It.IsAny <GroupKey>())).Returns(1);
mockConfig.Setup(m => m.GetTrippedDurationMillis(It.IsAny <GroupKey>())).Returns(trippedDurationMillis);
mockConfig.Setup(m => m.GetForceTripped(It.IsAny <GroupKey>())).Returns(false);
mockConfig.Setup(m => m.GetForceFixed(It.IsAny <GroupKey>())).Returns(false);
// 1 ops, 1% failure required to break.
var breaker = new FailurePercentageCircuitBreaker(AnyKey, manualClock, mockMetrics.Object, mockEvents.Object, mockConfig.Object, new DefaultMjolnirLogFactory());
// Act / Assert
Assert.False(breaker.IsAllowing()); // Should immediately trip.
manualClock.AddMilliseconds(trippedDurationMillis + 10);
Assert.True(breaker.IsAllowing()); // Single test is allowed.
Assert.False(breaker.IsAllowing());
manualClock.AddMilliseconds(trippedDurationMillis * 2);
breaker.MarkSuccess(trippedDurationMillis * 2);
// Metrics will have been reset.
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
private ResettingNumbersBucket CreateBucket()
{
var mockConfig = new Mock <IFailurePercentageCircuitBreakerConfig>(MockBehavior.Strict);
mockConfig.Setup(m => m.GetWindowMillis(It.IsAny <GroupKey>())).Returns(10000);
var clock = new ManualTestClock();
return(new ResettingNumbersBucket(AnyGroupKey, clock, mockConfig.Object, new DefaultMjolnirLogFactory()));
}
public void Increment_AfterPeriodExceeded_ResetsBeforeIncrementing()
{
const long periodMillis = 1000;
var clock = new ManualTestClock();
var bucket = new ResettingNumbersBucket(clock, new TransientConfigurableValue<long>(periodMillis));
bucket.Increment(CounterMetric.CommandSuccess);
clock.AddMilliseconds(periodMillis + 1);
Assert.Equal(1, bucket.GetCount(CounterMetric.CommandSuccess));
bucket.Increment(CounterMetric.CommandSuccess); // Should reset and then count one.
Assert.Equal(1, bucket.GetCount(CounterMetric.CommandSuccess)); // Should be 1, not 2.
}
public void Increment_AfterPeriodExceeded_ResetsBeforeIncrementing()
{
const long periodMillis = 1000;
var clock = new ManualTestClock();
var bucket = new ResettingNumbersBucket(clock, new TransientConfigurableValue <long>(periodMillis));
bucket.Increment(CounterMetric.CommandSuccess);
clock.AddMilliseconds(periodMillis + 1);
Assert.Equal(1, bucket.GetCount(CounterMetric.CommandSuccess));
bucket.Increment(CounterMetric.CommandSuccess); // Should reset and then count one.
Assert.Equal(1, bucket.GetCount(CounterMetric.CommandSuccess)); // Should be 1, not 2.
}
public void IsAllowing_AfterTrippedAndWithinWaitPeriod_Rejects()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(5000); // Half the wait duration.
Assert.False(breaker.IsAllowing());
}
public void IsAllowing_AfterTrippedAndAfterWaitPeriod_SendsSingleTestAndRejectsOthers()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(11000);
Assert.True(breaker.IsAllowing()); // Allow the first one, it's the single test.
Assert.False(breaker.IsAllowing()); // Reject the next one, the test was already allowed.
}
public void IsAllowing_AfterFailedSingleTest_KeepsBreakerTrippedAndSendsAnotherTestAfterAnotherDuration()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(11000);
Assert.True(breaker.IsAllowing()); // Single test.
// Advance to halfway through the duration. We should still be rejecting.
clock.AddMilliseconds(6000);
Assert.False(breaker.IsAllowing());
// No mark success call here. Metrics will probably have a failure added to it.
clock.AddMilliseconds(5000); // 6000 + 5000 = 11000 > 10000 (the duration).
Assert.True(breaker.IsAllowing()); // It's been another duration, we should allow another single test.
// Advance to halfway through the duration. We should still be rejecting.
clock.AddMilliseconds(6000);
Assert.False(breaker.IsAllowing());
// No mark success call here. Metrics will probably have a failure added to it.
clock.AddMilliseconds(5000); // 6000 + 5000 = 11000 > 10000 (the duration).
Assert.True(breaker.IsAllowing()); // It's been another duration, we should allow another single test.
// Advance a second or so, pretend the single test took some time.
clock.AddMilliseconds(500);
// Let's pretend this test succeeds. Mark it and reset the metrics.
breaker.MarkSuccess(0);
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
// We should immediately be opened.
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
public void GetSnapshot_NotCachedAndCached()
{
var mockStats = new Mock<IStats>();
var clock = new ManualTestClock();
var metrics = CreateMetrics("Test", mockStats, clock, 30000, 10000);
clock.AddMilliseconds(10100); // Pass the snapshot TTL.
metrics.GetSnapshot(); // Should create new snapshot.
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test CreateSnapshot", null, It.IsAny<TimeSpan>()), Times.Once);
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test GetSnapshot", null, It.IsAny<TimeSpan>()), Times.Once);
metrics.GetSnapshot(); // Should grab the cached one without re-creating.
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test CreateSnapshot", null, It.IsAny<TimeSpan>()), Times.Once); // Still once.
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test GetSnapshot", null, It.IsAny<TimeSpan>()), Times.Exactly(2)); // One more time.
}
public void AllowSingleTest_TrippedAndNotPastWaitDuration()
{
var mockStats = new Mock <IStats>();
var clock = new ManualTestClock();
var breaker = new BreakerBuilder(0, 0, "Test")
.WithStats(mockStats.Object)
.WithClock(clock)
.WithWaitMillis(1000)
.Create();
breaker.IsAllowing(); // Trip.
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "NotEligible", It.IsAny <TimeSpan>()), Times.Once);
// Don't advance the clock.
breaker.IsAllowing();
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "NotEligible", It.IsAny <TimeSpan>()), Times.Exactly(2));
}
public void AllowSingleTest_TrippedAndPastWaitDuration()
{
var mockStats = new Mock <IStats>();
var clock = new ManualTestClock();
var breaker = new BreakerBuilder(0, 0, "Test")
.WithStats(mockStats.Object)
.WithClock(clock)
.WithWaitMillis(1000)
.Create();
breaker.IsAllowing(); // Trip.
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "NotEligible", It.IsAny <TimeSpan>()), Times.Once);
clock.AddMilliseconds(2000); // Advance past wait duration.
breaker.IsAllowing();
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "Allowed", It.IsAny <TimeSpan>()), Times.Once);
}
public void MarkSuccess_WhenTrippedAndAfterWaitDuration_ResetsMetrics()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(1, 100);
var breaker = new BreakerBuilder(1, 50)
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Trip the breaker first.
clock.AddMilliseconds(11000);
Assert.True(breaker.IsAllowing()); // Single test...
breaker.MarkSuccess(0); // ... that's successful.
mockMetrics.Verify(m => m.Reset(), Times.Once);
}
public void GetSnapshot_NotCachedAndCached()
{
var mockStats = new Mock <IStats>();
var clock = new ManualTestClock();
var metrics = CreateMetrics("Test", mockStats, clock, 30000, 10000);
clock.AddMilliseconds(10100); // Pass the snapshot TTL.
metrics.GetSnapshot(); // Should create new snapshot.
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test CreateSnapshot", null, It.IsAny <TimeSpan>()), Times.Once);
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test GetSnapshot", null, It.IsAny <TimeSpan>()), Times.Once);
metrics.GetSnapshot(); // Should grab the cached one without re-creating.
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test CreateSnapshot", null, It.IsAny <TimeSpan>()), Times.Once); // Still once.
mockStats.Verify(m => m.Elapsed("mjolnir metrics Test GetSnapshot", null, It.IsAny <TimeSpan>()), Times.Exactly(2)); // One more time.
}
public void MarkSuccess_WhenTrippedAndAfterWaitDuration_ResetsMetrics()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(1, 100);
var breaker = new BreakerBuilder(1, 50)
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Trip the breaker first.
clock.AddMilliseconds(11000);
Assert.True(breaker.IsAllowing()); // Single test...
breaker.MarkSuccess(0); // ... that's successful.
mockMetrics.Verify(m => m.Reset(), Times.Once);
}
public void Increment_AfterPeriodExceeded_ResetsBeforeIncrementing()
{
const long periodMillis = 1000;
var mockConfig = new Mock <IFailurePercentageCircuitBreakerConfig>(MockBehavior.Strict);
mockConfig.Setup(m => m.GetWindowMillis(It.IsAny <GroupKey>())).Returns(periodMillis);
var clock = new ManualTestClock();
var bucket = new ResettingNumbersBucket(AnyGroupKey, clock, mockConfig.Object, new DefaultMjolnirLogFactory());
bucket.Increment(CounterMetric.CommandSuccess);
clock.AddMilliseconds(periodMillis + 1);
Assert.Equal(1, bucket.GetCount(CounterMetric.CommandSuccess));
bucket.Increment(CounterMetric.CommandSuccess); // Should reset and then count one.
Assert.Equal(1, bucket.GetCount(CounterMetric.CommandSuccess)); // Should be 1, not 2.
}
public void IsAllowing_WhenPropertiesForceFixedButBreakerWouldNormallyTrip_SilentlyTripsTheBreaker()
{
// Arrange
// Most property values don't matter, IsAllowing() should reject before it tries to use them.
var manualClock = new ManualTestClock();
var mockMetrics = new Mock <ICommandMetrics>();
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(2, 50));
var mockEvents = new Mock <IMetricEvents>();
var mockConfig = new Mock <IFailurePercentageCircuitBreakerConfig>();
mockConfig.Setup(m => m.GetMinimumOperations(It.IsAny <GroupKey>())).Returns(1);
mockConfig.Setup(m => m.GetThresholdPercentage(It.IsAny <GroupKey>())).Returns(25);
mockConfig.Setup(m => m.GetTrippedDurationMillis(It.IsAny <GroupKey>())).Returns(30000);
mockConfig.Setup(m => m.GetForceTripped(It.IsAny <GroupKey>())).Returns(false);
mockConfig.Setup(m => m.GetForceFixed(It.IsAny <GroupKey>())).Returns(true);
// We'll call IsAllowing() three times. The first two should force the breaker fixed,
// the third should un-force it. The breaker should have tripped by then, so the third
// call should show the breaker disallowing the call.
mockConfig.SetupSequence(m => m.GetForceFixed(It.IsAny <GroupKey>()))
.Returns(true)
.Returns(true)
.Returns(false);
var breaker = new FailurePercentageCircuitBreaker(AnyKey, manualClock, mockMetrics.Object, mockEvents.Object, mockConfig.Object, new DefaultMjolnirLogFactory());
// Act / Assert
Assert.True(breaker.IsAllowing()); // Will have tripped internally.
Assert.True(breaker.IsAllowing()); // Continues to allow even when tripped.
// Test that when the the forced fix property is no longer true, IsAllowing() then rejects.
// The Mock sequencing enables this.
Assert.False(breaker.IsAllowing());
}
public void MarkSuccess_ForLongRunningSingleTest_FixesBreaker()
{
// Since we use the elapsed time in MarkSuccess(), address the following situation:
// 1. Breaker trips
// 2. Window passes
// 3. Single test is allowed
// 4. Single test takes a long time (say, > 2 windows) to complete (even though it started after we tripped).
// Verify that:
// - No other requests are allowed while the single test is waiting.
// - The single test, if successful, fixes the breaker.
// This is somewhat unlikely since we probably wont have command timeouts
// that'd allow this. But worth verifying.
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(2, 100); // 2 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1)
.WithMockMetrics(mockMetrics)
.WithClock(clock)
.Create(); // 1 ops, 1% failure required to break.
var duration = breaker.Properties.TrippedDurationMillis;
Assert.False(breaker.IsAllowing()); // Should immediately trip.
clock.AddMilliseconds(duration.Value + 10);
Assert.True(breaker.IsAllowing()); // Single test is allowed.
Assert.False(breaker.IsAllowing());
clock.AddMilliseconds(duration.Value * 2);
breaker.MarkSuccess(duration.Value * 2);
// Metrics will have been reset.
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
public void GetSnapshot_WithinCachePeriod_ReturnsPreviousSnapshot()
{
var clock = new ManualTestClock();
// Within the metrics, the last snapshot timestamp will probably be zero.
// Let's start our clock with something far away from zero.
clock.AddMilliseconds(new SystemClock().GetMillisecondTimestamp());
var metrics = new StandardCommandMetrics(
GroupKey.Named("Test"),
new TransientConfigurableValue <long>(10000),
new TransientConfigurableValue <long>(1000),
clock,
new IgnoringStats());
metrics.MarkCommandSuccess();
metrics.GetSnapshot(); // Take the first snapshot to cache it.
metrics.MarkCommandSuccess();
clock.AddMilliseconds(500); // Still within the snapshot TTL (1000).
Assert.Equal(1, metrics.GetSnapshot().Total);
clock.AddMilliseconds(1000); // Push time past the TTL.
Assert.Equal(2, metrics.GetSnapshot().Total);
}
public void GetSnapshot_WithinCachePeriod_ReturnsPreviousSnapshot()
{
var clock = new ManualTestClock();
// Within the metrics, the last snapshot timestamp will probably be zero.
// Let's start our clock with something far away from zero.
clock.AddMilliseconds(new SystemClock().GetMillisecondTimestamp());
var metrics = new StandardCommandMetrics(
GroupKey.Named("Test"),
new TransientConfigurableValue<long>(10000),
new TransientConfigurableValue<long>(1000),
clock,
new IgnoringStats());
metrics.MarkCommandSuccess();
metrics.GetSnapshot(); // Take the first snapshot to cache it.
metrics.MarkCommandSuccess();
clock.AddMilliseconds(500); // Still within the snapshot TTL (1000).
Assert.Equal(1, metrics.GetSnapshot().Total);
clock.AddMilliseconds(1000); // Push time past the TTL.
Assert.Equal(2, metrics.GetSnapshot().Total);
}
public void MarkSuccess_ImmediatelyAfterTrippingButStartedBeforeTripped_DoesntImmediatelyFix()
{
// 1. Breaker is near tripping.
// 2. Operation A and B are Allowed and begin work.
// 3. Before Operation A completes
// a. Operation B has an error and updates metrics.
// b. Operation C calls IsAllowing(), which trips breaker.
// 4. Operation A completes successfully and calls MarkSuccess().
// 5. Since breaker is tripped but we haven't hit our wait duration yet,
// MarkSuccess() should result in the the breaker remaining tripped.
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(2, 100); // 2 ops, 100% failing.
var breaker = new BreakerBuilder(5, 1)
.WithMockMetrics(mockMetrics)
.WithClock(clock)
.Create(); // 5 ops, 1% failure required to break.
// #2. Operation A is allowed and begins.
Assert.True(breaker.IsAllowing()); // Haven't hit the 1-operation threshold yet, should be allowed.
// #3a. Operation B errors
breaker.Properties.MinimumOperations.Value = 1; // Easier to test by changing the breaker conditions.
// #3b. Breaker exceeds metrics thresholds, Operation C tries to IsAllowing() and trips breaker.
Assert.False(breaker.IsAllowing());
// #4. Operation A completes successfully.
// Breaker's internal _lastTrippedTimestamp should be equal to zero (current clock time).
// Since we say the transaction took 100ms, that'll be before the breaker tripped, and should
// be ignored.
breaker.MarkSuccess(100);
// #5. Make sure we're still tripped and we didn't reset the metrics.
Assert.False(breaker.IsAllowing());
mockMetrics.Verify(m => m.Reset(), Times.Never);
}
public void MarkSuccess_ImmediatelyAfterTrippingButStartedBeforeTripped_DoesntImmediatelyFix()
{
// 1. Breaker is near tripping.
// 2. Operation A and B are Allowed and begin work.
// 3. Before Operation A completes
// a. Operation B has an error and updates metrics.
// b. Operation C calls IsAllowing(), which trips breaker.
// 4. Operation A completes successfully and calls MarkSuccess().
// 5. Since breaker is tripped but we haven't hit our wait duration yet,
// MarkSuccess() should result in the the breaker remaining tripped.
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(2, 100); // 2 ops, 100% failing.
var breaker = new BreakerBuilder(5, 1)
.WithMockMetrics(mockMetrics)
.WithClock(clock)
.Create(); // 5 ops, 1% failure required to break.
// #2. Operation A is allowed and begins.
Assert.True(breaker.IsAllowing()); // Haven't hit the 1-operation threshold yet, should be allowed.
// #3a. Operation B errors
breaker.Properties.MinimumOperations.Value = 1; // Easier to test by changing the breaker conditions.
// #3b. Breaker exceeds metrics thresholds, Operation C tries to IsAllowing() and trips breaker.
Assert.False(breaker.IsAllowing());
// #4. Operation A completes successfully.
// Breaker's internal _lastTrippedTimestamp should be equal to zero (current clock time).
// Since we say the transaction took 100ms, that'll be before the breaker tripped, and should
// be ignored.
breaker.MarkSuccess(100);
// #5. Make sure we're still tripped and we didn't reset the metrics.
Assert.False(breaker.IsAllowing());
mockMetrics.Verify(m => m.Reset(), Times.Never);
}
public void IsAllowing_MultipleDurationsBetweenFailureAndNextFailure_KeepsBreakerTripped()
{
const long durationMillis = 10000;
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(durationMillis)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Trip the breaker.
clock.AddMilliseconds(durationMillis * 5);
Assert.True(breaker.IsAllowing()); // Single test, but it won't MarkSuccess().
Assert.False(breaker.IsAllowing()); // Make sure the last one was the single test.
clock.AddMilliseconds(durationMillis * 5);
Assert.True(breaker.IsAllowing()); // Single test, but it won't MarkSuccess().
Assert.False(breaker.IsAllowing()); // Make sure the last one was the single test.
}
public void GetSnapshot_WithinCachePeriod_ReturnsPreviousSnapshot()
{
var clock = new ManualTestClock();
var key = AnyGroupKey;
var mockConfig = new Mock <IFailurePercentageCircuitBreakerConfig>(MockBehavior.Strict);
mockConfig.Setup(m => m.GetWindowMillis(key)).Returns(10000);
mockConfig.Setup(m => m.GetSnapshotTtlMillis(key)).Returns(1000);
// Within the metrics, the last snapshot timestamp will probably be zero.
// Let's start our clock with something far away from zero.
clock.AddMilliseconds(new UtcSystemClock().GetMillisecondTimestamp());
var metrics = new StandardCommandMetrics(key, mockConfig.Object, clock, new DefaultMjolnirLogFactory());
metrics.MarkCommandSuccess();
metrics.GetSnapshot(); // Take the first snapshot to cache it.
metrics.MarkCommandSuccess();
clock.AddMilliseconds(500); // Still within the snapshot TTL (1000).
Assert.Equal(1, metrics.GetSnapshot().Total);
clock.AddMilliseconds(1000); // Push time past the TTL.
Assert.Equal(2, metrics.GetSnapshot().Total);
}
public void IsAllowing_MultipleDurationsBetweenFailureAndNextSuccess_FixesBreakerOnSuccess()
{
const long durationMillis = 10000;
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(durationMillis)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Trip the breaker.
clock.AddMilliseconds(durationMillis * 5);
Assert.True(breaker.IsAllowing()); // Single test.
breaker.MarkSuccess(0);
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
public void AllowSingleTest_TrippedAndPastWaitDuration()
{
var mockStats = new Mock<IStats>();
var clock = new ManualTestClock();
var breaker = new BreakerBuilder(0, 0, "Test")
.WithStats(mockStats.Object)
.WithClock(clock)
.WithWaitMillis(1000)
.Create();
breaker.IsAllowing(); // Trip.
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "NotEligible", It.IsAny<TimeSpan>()), Times.Once);
clock.AddMilliseconds(2000); // Advance past wait duration.
breaker.IsAllowing();
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "Allowed", It.IsAny<TimeSpan>()), Times.Once);
}
public void IsAllowing_MultipleDurationsBetweenFailureAndNextSuccess_FixesBreakerOnSuccess()
{
const long durationMillis = 10000;
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(durationMillis)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Trip the breaker.
clock.AddMilliseconds(durationMillis * 5);
Assert.True(breaker.IsAllowing()); // Single test.
breaker.MarkSuccess(0);
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
private ResettingNumbersBucket CreateBucket()
{
var clock = new ManualTestClock();
return(new ResettingNumbersBucket(clock, new TransientConfigurableValue <long>(10000)));
}
public void IsAllowing_MultipleDurationsBetweenFailureAndNextFailure_KeepsBreakerTripped()
{
const long durationMillis = 10000;
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(durationMillis)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Trip the breaker.
clock.AddMilliseconds(durationMillis * 5);
Assert.True(breaker.IsAllowing()); // Single test, but it won't MarkSuccess().
Assert.False(breaker.IsAllowing()); // Make sure the last one was the single test.
clock.AddMilliseconds(durationMillis * 5);
Assert.True(breaker.IsAllowing()); // Single test, but it won't MarkSuccess().
Assert.False(breaker.IsAllowing()); // Make sure the last one was the single test.
}
public void IsAllowing_AfterFailedSingleTest_KeepsBreakerTrippedAndSendsAnotherTestAfterAnotherDuration()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(11000);
Assert.True(breaker.IsAllowing()); // Single test.
// Advance to halfway through the duration. We should still be rejecting.
clock.AddMilliseconds(6000);
Assert.False(breaker.IsAllowing());
// No mark success call here. Metrics will probably have a failure added to it.
clock.AddMilliseconds(5000); // 6000 + 5000 = 11000 > 10000 (the duration).
Assert.True(breaker.IsAllowing()); // It's been another duration, we should allow another single test.
// Advance to halfway through the duration. We should still be rejecting.
clock.AddMilliseconds(6000);
Assert.False(breaker.IsAllowing());
// No mark success call here. Metrics will probably have a failure added to it.
clock.AddMilliseconds(5000); // 6000 + 5000 = 11000 > 10000 (the duration).
Assert.True(breaker.IsAllowing()); // It's been another duration, we should allow another single test.
// Advance a second or so, pretend the single test took some time.
clock.AddMilliseconds(500);
// Let's pretend this test succeeds. Mark it and reset the metrics.
breaker.MarkSuccess(0);
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
// We should immediately be opened.
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
private ResettingNumbersBucket CreateBucket()
{
var clock = new ManualTestClock();
return new ResettingNumbersBucket(clock, new TransientConfigurableValue<long>(10000));
}
public void ManualTestClock_GetMillisecondTimestamp_StartsAtZero()
{
var clock = new ManualTestClock();
Assert.Equal(0, clock.GetMillisecondTimestamp());
}
public void MarkSuccess_ForLongRunningSingleTest_FixesBreaker()
{
// Since we use the elapsed time in MarkSuccess(), address the following situation:
// 1. Breaker trips
// 2. Window passes
// 3. Single test is allowed
// 4. Single test takes a long time (say, > 2 windows) to complete (even though it started after we tripped).
// Verify that:
// - No other requests are allowed while the single test is waiting.
// - The single test, if successful, fixes the breaker.
// This is somewhat unlikely since we probably wont have command timeouts
// that'd allow this. But worth verifying.
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(2, 100); // 2 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1)
.WithMockMetrics(mockMetrics)
.WithClock(clock)
.Create(); // 1 ops, 1% failure required to break.
var duration = breaker.Properties.TrippedDurationMillis;
Assert.False(breaker.IsAllowing()); // Should immediately trip.
clock.AddMilliseconds(duration.Value + 10);
Assert.True(breaker.IsAllowing()); // Single test is allowed.
Assert.False(breaker.IsAllowing());
clock.AddMilliseconds(duration.Value * 2);
breaker.MarkSuccess(duration.Value * 2);
// Metrics will have been reset.
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}
public void ManualTestClock_AddMilliseconds_DisallowsNegatives()
{
var clock = new ManualTestClock();
Assert.Throws <ArgumentException>(() => clock.AddMilliseconds(-10));
}
public void IsAllowing_AfterTrippedAndWithinWaitPeriod_Rejects()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(5000); // Half the wait duration.
Assert.False(breaker.IsAllowing());
}
public void IsAllowing_AfterTrippedAndAfterWaitPeriod_SendsSingleTestAndRejectsOthers()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(11000);
Assert.True(breaker.IsAllowing()); // Allow the first one, it's the single test.
Assert.False(breaker.IsAllowing()); // Reject the next one, the test was already allowed.
}
public void AllowSingleTest_TrippedAndNotPastWaitDuration()
{
var mockStats = new Mock<IStats>();
var clock = new ManualTestClock();
var breaker = new BreakerBuilder(0, 0, "Test")
.WithStats(mockStats.Object)
.WithClock(clock)
.WithWaitMillis(1000)
.Create();
breaker.IsAllowing(); // Trip.
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "NotEligible", It.IsAny<TimeSpan>()), Times.Once);
// Don't advance the clock.
breaker.IsAllowing();
mockStats.Verify(m => m.Elapsed("mjolnir breaker Test AllowSingleTest", "NotEligible", It.IsAny<TimeSpan>()), Times.Exactly(2));
}
public void IsAllowing_AfterSuccessfulSingleTest_FixesBreaker()
{
var clock = new ManualTestClock();
var mockMetrics = CreateMockMetricsWithSnapshot(10, 100); // 10 ops, 100% failing.
var breaker = new BreakerBuilder(1, 1) // Trip at 1 op, 1% failing.
.WithMockMetrics(mockMetrics)
.WithWaitMillis(10000)
.WithClock(clock)
.Create();
Assert.False(breaker.IsAllowing()); // Should reject and trip.
clock.AddMilliseconds(11000);
breaker.IsAllowing(); // Send the single test.
clock.AddMilliseconds(500); // Pretend the test operation took a bit (not really necessary here).
breaker.MarkSuccess(0); // The single test transaction marks a success.
// Metrics should be reset.
mockMetrics.Verify(m => m.Reset(), Times.Once);
mockMetrics.Setup(m => m.GetSnapshot()).Returns(new MetricsSnapshot(0, 0));
// Should be fixed now.
// Test IsAllowing() twice to make sure it's not just the single test we're allowing.
Assert.True(breaker.IsAllowing());
Assert.True(breaker.IsAllowing());
}