feat(telemetry): instrument inference duration and frame age

pkg/metrics/metrics.go

@@ -0,0 +1,69 @@
+package metrics
+
+import (
+	"context"
+	stdout "go.opentelemetry.io/otel/exporters/stdout/stdoutmetric"
+	"go.opentelemetry.io/otel/metric"
+	"go.opentelemetry.io/otel/metric/global"
+	"go.opentelemetry.io/otel/metric/unit"
+	controller "go.opentelemetry.io/otel/sdk/metric/controller/basic"
+	processor "go.opentelemetry.io/otel/sdk/metric/processor/basic"
+	"go.opentelemetry.io/otel/sdk/metric/selector/simple"
+	"go.uber.org/zap"
+)
+
+var (
+	FrameAge          metric.Int64Histogram
+	InferenceDuration metric.Int64Histogram
+)
+
+func initMeter(ctx context.Context) func() {
+	zap.S().Info("init telemetry")
+	exporter, err := stdout.New(
+		stdout.WithPrettyPrint(),
+	)
+	if err != nil {
+		zap.S().Panicf("failed to initialize prometheus exporter %v", err)
+	}
+
+	pusher := controller.New(
+		processor.NewFactory(
+			simple.NewWithInexpensiveDistribution(),
+			//simple.NewWithHistogramDistribution(
+			//	histogram.WithExplicitBoundaries(
+			//		[]float64{.005, .5, 1, 2.5, 5, 10, 20, 50, 100},
+			//	),
+			//),
+			exporter,
+		),
+		controller.WithExporter(exporter),
+	)
+
+	if err = pusher.Start(ctx); err != nil {
+		zap.S().Fatalf("starting push controller: %v", err)
+	}
+	global.SetMeterProvider(pusher)
+	return func() {
+		if err := pusher.Stop(ctx); err != nil {
+			zap.S().Fatalf("stopping push controller: %v", err)
+		}
+	}
+
+}
+
+func Init(ctx context.Context) func() {
+	cleaner := initMeter(ctx)
+
+	meter := global.Meter("robocar/rc-steering")
+
+	FrameAge = metric.Must(meter).NewInt64Histogram(
+		"robocar.frame_age",
+		metric.WithUnit(unit.Milliseconds),
+		metric.WithDescription("time before frame processing"))
+	InferenceDuration = metric.Must(meter).NewInt64Histogram(
+		"robocar.inference_duration",
+		metric.WithUnit(unit.Milliseconds),
+		metric.WithDescription("tensorflow inference duration"))
+
+	return cleaner
+}