add timer and meter clear

meter.go

@@ -16,6 +16,7 @@ type Meter interface {
 	RateMean() float64
 	Snapshot() Meter
 	Stop()
+	Clear()
 }
 
 // GetOrRegisterMeter returns an existing Meter or constructs and registers a
@@ -95,6 +96,9 @@ func (m *MeterSnapshot) Snapshot() Meter { return m }
 // Stop is a no-op.
 func (m *MeterSnapshot) Stop() {}
 
+// Clear is a no-op.
+func (m *MeterSnapshot) Clear(){}
+
 // NilMeter is a no-op Meter.
 type NilMeter struct{}
 
@@ -122,6 +126,9 @@ func (NilMeter) Snapshot() Meter { return NilMeter{} }
 // Stop is a no-op.
 func (NilMeter) Stop() {}
 
+// Clear is a no-op.
+func (NilMeter) Clear(){}
+
 // StandardMeter is the standard implementation of a Meter.
 type StandardMeter struct {
 	lock        sync.RWMutex
@@ -154,6 +161,18 @@ func (m *StandardMeter) Stop() {
 	}
 }
 
+// Clear resets the meter.
+func (m *StandardMeter) Clear(){
+	m.lock.Lock()
+	defer m.lock.Unlock()
+
+	m.snapshot = &MeterSnapshot{}
+	m.a1=NewEWMA1()
+	m.a5=NewEWMA5()
+	m.a15=NewEWMA15()
+	m.startTime = time.Now()
+}
+
 // Count returns the number of events recorded.
 func (m *StandardMeter) Count() int64 {
 	m.lock.RLock()

meter_test.go

@@ -71,3 +71,13 @@ func TestMeterZero(t *testing.T) {
 		t.Errorf("m.Count(): 0 != %v\n", count)
 	}
 }
+
+func TestMeterClear(t *testing.T) {
+	m := NewMeter()
+	m.Mark(1234)
+	m.Clear()
+
+	if m.Count()>0{
+		t.Errorf("meter clear error.")
+	}
+}

timer.go

@@ -25,6 +25,7 @@ type Timer interface {
 	Update(time.Duration)
 	UpdateSince(time.Time)
 	Variance() float64
+	Clear()
 }
 
 // GetOrRegisterTimer returns an existing Timer or constructs and registers a
@@ -137,6 +138,9 @@ func (NilTimer) UpdateSince(time.Time) {}
 // Variance is a no-op.
 func (NilTimer) Variance() float64 { return 0.0 }
 
+// Clear is a no-op.
+func (NilTimer) Clear(){}
+
 // StandardTimer is the standard implementation of a Timer and uses a Histogram
 // and Meter.
 type StandardTimer struct {
@@ -249,6 +253,14 @@ func (t *StandardTimer) Variance() float64 {
 	return t.histogram.Variance()
 }
 
+// Clear stops the meter and clear the histogram.
+func (t *StandardTimer) Clear(){
+	t.mutex.Lock()
+	t.mutex.Unlock()
+	t.meter.Clear()
+	t.histogram.Clear()
+}
+
 // TimerSnapshot is a read-only copy of another Timer.
 type TimerSnapshot struct {
 	histogram *HistogramSnapshot
@@ -327,3 +339,6 @@ func (*TimerSnapshot) UpdateSince(time.Time) {
 // Variance returns the variance of the values at the time the snapshot was
 // taken.
 func (t *TimerSnapshot) Variance() float64 { return t.histogram.Variance() }
+
+// Clear is a no-op.
+func (t *TimerSnapshot) Clear(){}

timer_test.go

@@ -93,6 +93,18 @@ func TestTimerZero(t *testing.T) {
 	}
 }
 
+func TestTimerClear(t *testing.T) {
+	tm := NewTimer()
+	tm.Time(func() { time.Sleep(50e6) })
+	if max := tm.Max(); 45e6 > max || max > 55e6 {
+		t.Errorf("tm.Max(): 45e6 > %v || %v > 55e6\n", max, max)
+	}
+	tm.Clear()
+	if tm.Count()>0{
+		t.Errorf("timer clear error.")
+	}
+}
+
 func ExampleGetOrRegisterTimer() {
 	m := "account.create.latency"
 	t := GetOrRegisterTimer(m, nil)