Small example of how golang metric sdk histograms behave with async i…

…nstruments

gometrictest/go.mod

@@ -0,0 +1,18 @@
+module github.com/aabmass/gometrictest
+
+go 1.22
+
+require (
+	go.opentelemetry.io/otel v1.21.0
+	go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v0.44.0
+	go.opentelemetry.io/otel/sdk v1.21.0
+	go.opentelemetry.io/otel/sdk/metric v1.21.0
+)
+
+require (
+	github.com/go-logr/logr v1.3.0 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	go.opentelemetry.io/otel/metric v1.21.0 // indirect
+	go.opentelemetry.io/otel/trace v1.21.0 // indirect
+	golang.org/x/sys v0.14.0 // indirect
+)

gometrictest/go.sum

@@ -0,0 +1,29 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.3.0 h1:2y3SDp0ZXuc6/cjLSZ+Q3ir+QB9T/iG5yYRXqsagWSY=
+github.com/go-logr/logr v1.3.0/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+go.opentelemetry.io/otel v1.21.0 h1:hzLeKBZEL7Okw2mGzZ0cc4k/A7Fta0uoPgaJCr8fsFc=
+go.opentelemetry.io/otel v1.21.0/go.mod h1:QZzNPQPm1zLX4gZK4cMi+71eaorMSGT3A4znnUvNNEo=
+go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v0.44.0 h1:dEZWPjVN22urgYCza3PXRUGEyCB++y1sAqm6guWFesk=
+go.opentelemetry.io/otel/exporters/stdout/stdoutmetric v0.44.0/go.mod h1:sTt30Evb7hJB/gEk27qLb1+l9n4Tb8HvHkR0Wx3S6CU=
+go.opentelemetry.io/otel/metric v1.21.0 h1:tlYWfeo+Bocx5kLEloTjbcDwBuELRrIFxwdQ36PlJu4=
+go.opentelemetry.io/otel/metric v1.21.0/go.mod h1:o1p3CA8nNHW8j5yuQLdc1eeqEaPfzug24uvsyIEJRWM=
+go.opentelemetry.io/otel/sdk v1.21.0 h1:FTt8qirL1EysG6sTQRZ5TokkU8d0ugCj8htOgThZXQ8=
+go.opentelemetry.io/otel/sdk v1.21.0/go.mod h1:Nna6Yv7PWTdgJHVRD9hIYywQBRx7pbox6nwBnZIxl/E=
+go.opentelemetry.io/otel/sdk/metric v1.21.0 h1:smhI5oD714d6jHE6Tie36fPx4WDFIg+Y6RfAY4ICcR0=
+go.opentelemetry.io/otel/sdk/metric v1.21.0/go.mod h1:FJ8RAsoPGv/wYMgBdUJXOm+6pzFY3YdljnXtv1SBE8Q=
+go.opentelemetry.io/otel/trace v1.21.0 h1:WD9i5gzvoUPuXIXH24ZNBudiarZDKuekPqi/E8fpfLc=
+go.opentelemetry.io/otel/trace v1.21.0/go.mod h1:LGbsEB0f9LGjN+OZaQQ26sohbOmiMR+BaslueVtS/qQ=
+golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
+golang.org/x/sys v0.14.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

gometrictest/main.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"log"
+	"os"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+	"go.opentelemetry.io/otel/metric"
+	sdkmetric "go.opentelemetry.io/otel/sdk/metric"
+	"go.opentelemetry.io/otel/sdk/resource"
+
+	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
+)
+
+func main() {
+	// Create resource.
+	res, err := resource.Merge(resource.Default(),
+		resource.NewWithAttributes(semconv.SchemaURL,
+			semconv.ServiceName("my-service"),
+			semconv.ServiceVersion("0.1.0"),
+		))
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	encoder := json.NewEncoder(os.Stdout)
+	encoder.SetIndent("", "  ")
+	exporter, err := stdoutmetric.New(
+		stdoutmetric.WithEncoder(encoder),
+	)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	reader := sdkmetric.NewPeriodicReader(exporter)
+
+	// Create a meter provider.
+	// You can pass this instance directly to your instrumented code if it
+	// accepts a MeterProvider instance.
+	meterProvider := sdkmetric.NewMeterProvider(
+		sdkmetric.WithResource(res),
+		sdkmetric.WithReader(reader),
+		sdkmetric.WithView(sdkmetric.NewView(
+			sdkmetric.Instrument{Name: "*"},
+			sdkmetric.Stream{Aggregation: sdkmetric.AggregationExplicitBucketHistogram{
+				Boundaries: []float64{0, 10, 100, 1000},
+			}},
+		)),
+	)
+
+	// Handle shutdown properly so that nothing leaks.
+	defer func() {
+		err := meterProvider.Shutdown(context.Background())
+		if err != nil {
+			log.Fatalln(err)
+		}
+	}()
+
+	// Register as global meter provider so that it can be used via otel.Meter
+	// and accessed using otel.GetMeterProvider.
+	// Most instrumentation libraries use the global meter provider as default.
+	// If the global meter provider is not set then a no-op implementation
+	// is used, which fails to generate data.
+	otel.SetMeterProvider(meterProvider)
+
+	_, err = otel.Meter("foo").Int64ObservableCounter(
+		"observableCounter",
+		metric.WithInt64Callback(callback),
+	)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	_, err = otel.Meter("foo").Int64ObservableGauge(
+		"obseravableGauge",
+		metric.WithInt64Callback(callback),
+	)
+	if err != nil {
+		log.Fatalln(err)
+	}
+}
+
+func callback(ctx context.Context, io metric.Int64Observer) error {
+	io.Observe(12)
+	io.Observe(112)
+	io.Observe(1112)
+	return nil
+}