add 'Must' style methods for different components

examples/acme/main.go

@@ -63,35 +63,17 @@ func main() {
 		panic(err)
 	}
 
-	err = writer.RegisterIndom(indom)
-	if err != nil {
-		panic(err)
-	}
-
-	err = writer.Register(countmetric)
-	if err != nil {
-		panic(err)
-	}
-
-	err = writer.Register(timemetric)
-	if err != nil {
-		panic(err)
-	}
+	writer.MustRegisterIndom(indom)
+	writer.MustRegister(countmetric)
+	writer.MustRegister(timemetric)
 
-	err = writer.Start()
-	if err != nil {
-		panic(err)
-	}
+	writer.MustStart()
+	defer writer.MustStop()
 
 	time.Sleep(time.Second * 5)
 	err = countmetric.SetInstance("Anvils", 42)
 	if err != nil {
 		panic(err)
 	}
 	time.Sleep(time.Second * 5)
-
-	err = writer.Stop()
-	if err != nil {
-		panic(err)
-	}
 }

examples/http_counter/server.go

@@ -8,10 +8,11 @@ import (
 	"github.com/performancecopilot/speed"
 )
 
-var metric *speed.PCPSingletonMetric
+// TODO: replace the raw metric with a Counter once defined
 
-func main() {
+var metric speed.SingletonMetric
 
+func main() {
 	var err error
 	metric, err = speed.NewPCPSingletonMetric(
 		0,
@@ -31,16 +32,10 @@ func main() {
 		panic(err)
 	}
 
-	err = writer.Register(metric)
-	if err != nil {
-		panic(err)
-	}
+	writer.MustRegister(metric)
 
-	err = writer.Start()
-	if err != nil {
-		panic(err)
-	}
-	defer writer.Stop()
+	writer.MustStart()
+	defer writer.MustStop()
 
 	http.HandleFunc("/increment", handleIncrement)
 	go http.ListenAndServe(":8080", nil)
@@ -53,6 +48,6 @@ func main() {
 func handleIncrement(w http.ResponseWriter, r *http.Request) {
 	v := metric.Val().(int32)
 	v++
-	metric.Set(v)
+	metric.MustSet(v)
 	fmt.Fprintf(w, "incremented\n")
 }

examples/instance_string/main.go

@@ -26,27 +26,20 @@ func main() {
 		panic(err)
 	}
 
-	err = w.Start()
-	if err != nil {
-		panic(err)
-	}
+	w.MustStart()
+	defer w.MustStop()
 
 	metric := m.(speed.InstanceMetric)
 	for i := 0; i < *timelimit; i++ {
 		v, _ := metric.ValInstance("go")
-		metric.SetInstance("go", v.(uint64)*2)
+		metric.MustSetInstance("go", v.(uint64)*2)
 
 		v, _ = metric.ValInstance("javascript")
-		metric.SetInstance("javascript", v.(uint64)+10)
+		metric.MustSetInstance("javascript", v.(uint64)+10)
 
 		v, _ = metric.ValInstance("php")
-		metric.SetInstance("php", v.(uint64)+1)
+		metric.MustSetInstance("php", v.(uint64)+1)
 
 		time.Sleep(time.Second)
 	}
-
-	err = w.Stop()
-	if err != nil {
-		panic(err)
-	}
 }

examples/simple/main.go

@@ -26,18 +26,11 @@ func main() {
 		panic(err)
 	}
 
-	err = writer.Register(metric)
-	if err != nil {
-		panic(err)
-	}
+	writer.MustRegister(metric)
 
-	err = writer.Start()
-	if err != nil {
-		panic(err)
-	}
+	writer.MustStart()
+	defer writer.MustStop()
 
 	fmt.Println("The metric is currently mapped as mmv.simple.simple.counter, to stop the mapping, press enter")
 	os.Stdin.Read(make([]byte, 1))
-
-	writer.Stop()
 }

examples/singleton_counter/main.go

@@ -38,18 +38,14 @@ func main() {
 		panic(err)
 	}
 
-	err = writer.Start()
-	if err != nil {
-		panic(err)
-	}
+	writer.MustStart()
+	defer writer.MustStop()
 
 	fmt.Println("The metric should be visible as mmv.singletoncounter.counter")
 	for i := 0; i < *timelimit; i++ {
 		v := metric.Val().(int32)
 		v++
+		metric.MustSet(v)
 		time.Sleep(time.Second)
-		metric.Set(v)
 	}
-
-	writer.Stop()
 }

examples/singleton_string/main.go

@@ -23,21 +23,14 @@ func main() {
 		panic(err)
 	}
 
-	err = w.Start()
-	if err != nil {
-		panic(err)
-	}
+	w.MustStart()
+	defer w.MustStop()
 
 	metric := m.(speed.SingletonMetric)
 	for i := 0; i < *timelimit; i++ {
 		val := metric.Val().(int32)
 		val++
-		metric.Set(val)
+		metric.MustSet(val)
 		time.Sleep(time.Second)
 	}
-
-	err = w.Stop()
-	if err != nil {
-		panic(err)
-	}
 }

metrics.go

@@ -256,8 +256,11 @@ type SingletonMetric interface {
 	// gets the value of the metric
 	Val() interface{}
 
-	// Sets the value of the metric to a value, optionally returns an error on failure
+	// sets the value of the metric to a value, optionally returns an error on failure
 	Set(interface{}) error
+
+	// tries to set and panics on error
+	MustSet(interface{})
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -272,6 +275,9 @@ type InstanceMetric interface {
 
 	// sets the value of a particular instance
 	SetInstance(string, interface{}) error
+
+	// tries to set the value of a particular instance and panics on error
+	MustSetInstance(string, interface{})
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -424,6 +430,13 @@ func (m *PCPSingletonMetric) Set(val interface{}) error {
 	return nil
 }
 
+// MustSet is a Set that panics
+func (m *PCPSingletonMetric) MustSet(val interface{}) {
+	if err := m.Set(val); err != nil {
+		panic(err)
+	}
+}
+
 // Indom returns the instance domain for a PCPSingletonMetric
 func (m *PCPSingletonMetric) Indom() *PCPInstanceDomain { return nil }
 
@@ -523,3 +536,10 @@ func (m *PCPInstanceMetric) SetInstance(instance string, val interface{}) error
 	m.vals[instance].val = val
 	return nil
 }
+
+// MustSetInstance is a SetInstance that panics
+func (m *PCPInstanceMetric) MustSetInstance(instance string, val interface{}) {
+	if err := m.SetInstance(instance, val); err != nil {
+		panic(err)
+	}
+}