For a FrequencyBreaker, Failures() should return the count since the …

…duration start, even after resetting.

Using Failures() in a monitoring system will always show 0 if traffic is doing Reset() on successful attempts faster than your sampling rate.

CHANGELOG.md

@@ -1,6 +1,17 @@
 # Changelog
 All notable changes to this project will be documented in this file.
 
+### 1.1.2 - 2014-08-20
+
+### Added
+- Nothing
+
+### Deprecated
+- Nothing
+
+### Fixed
+- For a FrequencyBreaker, Failures() should return the count since the duration start, even after resetting.
+
 ## 1.1.1 - 2014-08-20
 
 ### Added

circuitbreaker.go

@@ -213,15 +213,16 @@ type FrequencyBreaker struct {
 	// Threshold is the number of failures Breaker will allow before tripping
 	Threshold int64
 
-	_failureTick unsafe.Pointer
+	_failureTick      unsafe.Pointer
+	failuresSinceTick int64
 	*TrippableBreaker
 }
 
 // NewFrequencyBreaker returns a new FrequencyBreaker with the given duration
 // and failure threshold. If a duration is specified as 0 then no duration will be used and
 // the behavior will be the same as a ThresholdBreaker
 func NewFrequencyBreaker(duration time.Duration, threshold int64) *FrequencyBreaker {
-	return &FrequencyBreaker{duration, threshold, nil, NewTrippableBreaker(time.Millisecond * 500)}
+	return &FrequencyBreaker{duration, threshold, nil, 0, NewTrippableBreaker(time.Millisecond * 500)}
 }
 
 // Fail records a failure. If the failure count meets the threshold within the duration,
@@ -232,6 +233,7 @@ func (cb *FrequencyBreaker) Fail() {
 	}
 
 	cb.TrippableBreaker.Fail()
+	atomic.AddInt64(&cb.failuresSinceTick, 1)
 	failures := atomic.AddInt64(&cb.failures, 1)
 	if failures == cb.Threshold {
 		cb.Trip()
@@ -241,10 +243,15 @@ func (cb *FrequencyBreaker) Fail() {
 // Failures returns the number of failures for this circuit breaker. The failure count
 // for a FrequencyBreaker resets when the duration expires.
 func (cb *FrequencyBreaker) Failures() int64 {
-	if cb.Duration > 0 && (time.Since(cb.failureTick()) > cb.Duration) {
+	if cb.Duration <= 0 {
+		return cb.TrippableBreaker.Failures()
+	}
+
+	if time.Since(cb.failureTick()) > cb.Duration {
+		atomic.StoreInt64(&cb.failuresSinceTick, 0)
 		return 0
 	}
-	return cb.TrippableBreaker.Failures()
+	return atomic.LoadInt64(&cb.failuresSinceTick)
 }
 
 func (cb *FrequencyBreaker) frequencyFail() {

circuitbreaker_test.go

@@ -109,8 +109,8 @@ func TestThresholdBreaker(t *testing.T) {
 	}
 
 	cb.Reset()
-	if cb.failures != 0 {
-		t.Fatalf("expected reset to set failures to 0, got %d", cb.failures)
+	if failures := cb.Failures(); failures != 0 {
+		t.Fatalf("expected reset to set failures to 0, got %d", failures)
 	}
 	if cb.Tripped() {
 		t.Fatal("expected threshold breaker to be open")
@@ -227,6 +227,12 @@ func TestFrequencyBreakerFailures(t *testing.T) {
 	if f := cb.Failures(); f != 1 {
 		t.Fatalf("expected failure count of 1, got %d", f)
 	}
+
+	cb.Reset()
+	if f := cb.Failures(); f != 1 {
+		t.Fatalf("expected failure count of 1, got %d", f)
+	}
+
 	time.Sleep(time.Millisecond)
 	if f := cb.Failures(); f != 0 {
 		t.Fatalf("expected failures count to be 0, got %d", f)