Add AfterFunc configuration option to hystrix.ConfigureCloser (#111)

* Add AfterFunc configuration option to hystrix.ConfigureCloser

* Add AfterFunc field to ConfigureCloser Merge function

* Add json tag to omit AfterFunc from json encoding

Signed-off-by: Chris Guiney <chrisg@tune.com>

Co-authored-by: Chris Guiney <chrisg@tune.com>

v3/closers/hystrix/closer.go

@@ -36,6 +36,9 @@ var _ circuit.OpenToClosed = &Closer{}
 
 // ConfigureCloser configures values for Closer
 type ConfigureCloser struct {
+	// AfterFunc should simulate time.AfterFunc
+	AfterFunc func(time.Duration, func()) *time.Timer `json:"-"`
+
 	// SleepWindow is https://github.com/Netflix/Hystrix/wiki/Configuration#circuitbreakersleepwindowinmilliseconds
 	SleepWindow time.Duration
 	// HalfOpenAttempts is how many attempts to allow per SleepWindow
@@ -55,6 +58,9 @@ func (c *ConfigureCloser) Merge(other ConfigureCloser) {
 	if c.RequiredConcurrentSuccessful == 0 {
 		c.RequiredConcurrentSuccessful = other.RequiredConcurrentSuccessful
 	}
+	if c.AfterFunc == nil {
+		c.AfterFunc = other.AfterFunc
+	}
 }
 
 var defaultConfigureCloser = ConfigureCloser{
@@ -141,6 +147,7 @@ func (s *Closer) SetConfigThreadSafe(config ConfigureCloser) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 	s.config = config
+	s.reopenCircuitCheck.TimeAfterFunc = config.AfterFunc
 	s.reopenCircuitCheck.SetSleepDuration(config.SleepWindow)
 	s.reopenCircuitCheck.SetEventCountToAllow(config.HalfOpenAttempts)
 	s.closeOnCurrentCount.Set(config.RequiredConcurrentSuccessful)

v3/closers/hystrix/closer_test.go

@@ -70,3 +70,68 @@ func TestCloser_ConcurrentAttempts(t *testing.T) {
 	// Should reset closer
 	assertBool(t, !c.ShouldClose(now), "Expected the circuit to not yet close")
 }
+
+func TestCloser_AfterFunc(t *testing.T) {
+	t.Run("afterfunc is used", func(t *testing.T) {
+		var invocations int
+		c := Closer{}
+		c.SetConfigNotThreadSafe(ConfigureCloser{
+			AfterFunc: func(d time.Duration, f func()) *time.Timer {
+				invocations++
+				return time.AfterFunc(d, f)
+			},
+			RequiredConcurrentSuccessful: 3,
+		})
+
+		now := time.Now()
+		c.Opened(now)
+		c.Success(now, time.Second)
+		c.Success(now, time.Second)
+		c.Success(now, time.Second)
+		c.Success(now, time.Second)
+
+		if invocations == 0 {
+			t.Error("Expected mock AfterFunc to be used")
+		}
+		t.Log("invocations: ", invocations)
+	})
+	t.Run("afterfunc is set if previously nil", func(t *testing.T) {
+		var (
+			countD int
+			c      = ConfigureCloser{AfterFunc: nil}
+			d      = ConfigureCloser{AfterFunc: func(d time.Duration, f func()) *time.Timer {
+				countD++
+				return time.AfterFunc(d+1, f)
+			}}
+		)
+		c.Merge(d)
+		_ = c.AfterFunc(time.Second, func() {})
+
+		if countD != 1 {
+			t.Errorf("expected merge to assign newer AfterFunc")
+		}
+	})
+	t.Run("afterfunc is not merged if already set", func(t *testing.T) {
+		var (
+			countC, countD int
+
+			c = ConfigureCloser{AfterFunc: func(d time.Duration, f func()) *time.Timer {
+				countC++
+				return time.AfterFunc(d, f)
+			}}
+			d = ConfigureCloser{AfterFunc: func(d time.Duration, f func()) *time.Timer {
+				countD++
+				return time.AfterFunc(d+1, f)
+			}}
+		)
+		c.Merge(d)
+		_ = c.AfterFunc(time.Second, func() {})
+
+		if countD > 0 {
+			t.Errorf("expected merge to maintain an already set AfterFunc")
+		}
+		if countC != 1 {
+			t.Errorf("expected post-merge to invoke initially set AfterFunc")
+		}
+	})
+}