meter: add option helper and provide default metric name and label prefix

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

meter/context.go

@@ -0,0 +1,34 @@
+package meter
+
+import (
+	"context"
+)
+
+type meterKey struct{}
+
+// FromContext get meter from context
+func FromContext(ctx context.Context) (Meter, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	c, ok := ctx.Value(meterKey{}).(Meter)
+	return c, ok
+}
+
+// NewContext put meter in context
+func NewContext(ctx context.Context, c Meter) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, meterKey{}, c)
+}
+
+// SetOption returns a function to setup a context with given value
+func SetOption(k, v interface{}) Option {
+	return func(o *Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}

meter/meter.go

@@ -8,7 +8,18 @@ import (
 )
 
 var (
-	DefaultReporter Meter = NewMeter()
+	// DefaultMeter is the default meter
+	DefaultMeter Meter = NewMeter()
+	// DefaultAddress data will be made available on this host:port
+	DefaultAddress = ":9090"
+	// DefaultPath the meter endpoint where the Meter data will be made available
+	DefaultPath = "/metrics"
+	// timingObjectives is the default spread of stats we maintain for timings / histograms:
+	//defaultTimingObjectives = map[float64]float64{0.0: 0, 0.5: 0.05, 0.75: 0.04, 0.90: 0.03, 0.95: 0.02, 0.98: 0.001, 1: 0}
+	// default metric prefix
+	DefaultMetricPrefix = "micro_"
+	// default label prefix
+	DefaultLabelPrefix = "micro_"
 )
 
 // Meter is an interface for collecting and instrumenting metrics

meter/options.go

@@ -7,15 +7,6 @@ import (
 	"github.com/unistack-org/micro/v3/metadata"
 )
 
-var (
-	// The Meter data will be made available on this port
-	DefaultAddress = ":9090"
-	// This is the endpoint where the Meter data will be made available ("/metrics" is the default)
-	DefaultPath = "/metrics"
-	// timingObjectives is the default spread of stats we maintain for timings / histograms:
-	//defaultTimingObjectives = map[float64]float64{0.0: 0, 0.5: 0.05, 0.75: 0.04, 0.90: 0.03, 0.95: 0.02, 0.98: 0.001, 1: 0}
-)
-
 // Option powers the configuration for metrics implementations:
 type Option func(*Options)
 
@@ -27,6 +18,8 @@ type Options struct {
 	//TimingObjectives map[float64]float64
 	Logger       logger.Logger
 	Context      context.Context
+	MetricPrefix string
+	LabelPrefix  string
 }
 
 // NewOptions prepares a set of options:
@@ -35,9 +28,10 @@ func NewOptions(opt ...Option) Options {
 		Address:      DefaultAddress,
 		Metadata:     metadata.New(3), // 3 elements contains service name, version and id
 		Path:         DefaultPath,
-		//	TimingObjectives: defaultTimingObjectives,
 		Context:      context.Background(),
 		Logger:       logger.DefaultLogger,
+		MetricPrefix: DefaultMetricPrefix,
+		LabelPrefix:  DefaultLabelPrefix,
 	}
 
 	for _, o := range opt {
@@ -47,7 +41,7 @@ func NewOptions(opt ...Option) Options {
 	return opts
 }
 
-// Cntext sets the metrics context
+// Context sets the metrics context
 func Context(ctx context.Context) Option {
 	return func(o *Options) {
 		o.Context = ctx