change(metric): metric instruments & instrument provider enhanced wit…

…h generics

metric/example_test.go

@@ -22,7 +22,6 @@ import (
 
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/metric/instrument"
-	"go.opentelemetry.io/otel/metric/instrument/syncfloat64"
 	"go.opentelemetry.io/otel/metric/unit"
 )
 
@@ -110,4 +109,5 @@ func ExampleMeter_asynchronous_multiple() {
 }
 
 // This is just an example, see the the contrib runtime instrumentation for real implementation.
-func computeGCPauses(ctx context.Context, recorder syncfloat64.Histogram, pauseBuff []uint64) {}
+func computeGCPauses(ctx context.Context, recorder instrument.SyncHistogram[float64], pauseBuff []uint64) {
+}

metric/instrument/type.go

@@ -0,0 +1,79 @@
+package instrument
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/attribute"
+)
+
+// SyncInstrumentProvider provides access to synchronous instruments.
+type SyncInstrumentProvider[T int64 | float64] interface {
+	// Counter creates an instrument for recording increasing values.
+	Counter(name string, opts ...Option) (SyncCounter[T], error)
+	// UpDownCounter creates an instrument for recording changes of a value.
+	UpDownCounter(name string, opts ...Option) (SyncUpDownCounter[T], error)
+	// Histogram creates an instrument for recording a distribution of values.
+	Histogram(name string, opts ...Option) (SyncHistogram[T], error)
+}
+
+// Counter is an instrument that records increasing values.
+type SyncCounter[T int64 | float64] interface {
+	// Add records a change to the counter.
+	Add(ctx context.Context, incr T, attrs ...attribute.KeyValue)
+
+	Synchronous
+}
+
+// UpDownCounter is an instrument that records increasing or decreasing values.
+type SyncUpDownCounter[T int64 | float64] interface {
+	// Add records a change to the counter.
+	Add(ctx context.Context, incr T, attrs ...attribute.KeyValue)
+
+	Synchronous
+}
+
+// Histogram is an instrument that records a distribution of values.
+type SyncHistogram[T int64 | float64] interface {
+	// Record adds an additional value to the distribution.
+	Record(ctx context.Context, incr T, attrs ...attribute.KeyValue)
+
+	Synchronous
+}
+
+// AsyncInstrumentProvider provides access to asynchronous instruments.
+type AsyncInstrumentProvider[T int64 | float64] interface {
+	// Counter creates an instrument for recording increasing values.
+	Counter(name string, opts ...Option) (AsyncCounter[T], error)
+	// UpDownCounter creates an instrument for recording changes of a value.
+	UpDownCounter(name string, opts ...Option) (AsyncUpDownCounter[T], error)
+	// Histogram creates an instrument for recording a distribution of values.
+	Gauge(name string, opts ...Option) (AsyncGauge[T], error)
+}
+
+// Counter is an instrument that records increasing values.
+type AsyncCounter[T int64 | float64] interface {
+	// Add records a change to the counter.
+	Observe(ctx context.Context, x T, attrs ...attribute.KeyValue)
+
+	Asynchronous
+}
+
+// UpDownCounter is an instrument that records increasing or decreasing values.
+type AsyncUpDownCounter[T int64 | float64] interface {
+	// Add records a change to the counter.
+	Observe(ctx context.Context, x T, attrs ...attribute.KeyValue)
+
+	Asynchronous
+}
+
+// Gauge is an instrument that records independent readings.
+type AsyncGauge[T int64 | float64] interface {
+	// Observe records the state of the instrument to be x.
+	//
+	// It is only valid to call this within a callback. If called outside of the
+	// registered callback it should have no effect on the instrument, and an
+	// error will be reported via the error handler.
+	Observe(ctx context.Context, x T, attrs ...attribute.KeyValue)
+
+	Asynchronous
+}