metric: add Enabled method to synchronous instruments (#7763)

Fixes https://github.com/open-telemetry/opentelemetry-go/issues/7681

metric/noop/noop.go

@@ -191,6 +191,9 @@ type Int64Counter struct{ embedded.Int64Counter }
 // Add performs no operation.
 func (Int64Counter) Add(context.Context, int64, ...metric.AddOption) {}
 
+// Enabled performs no operation.
+func (Int64Counter) Enabled(context.Context) bool { return false }
+
 // Float64Counter is an OpenTelemetry Counter used to record float64
 // measurements. It produces no telemetry.
 type Float64Counter struct{ embedded.Float64Counter }
@@ -198,6 +201,9 @@ type Float64Counter struct{ embedded.Float64Counter }
 // Add performs no operation.
 func (Float64Counter) Add(context.Context, float64, ...metric.AddOption) {}
 
+// Enabled performs no operation.
+func (Float64Counter) Enabled(context.Context) bool { return false }
+
 // Int64UpDownCounter is an OpenTelemetry UpDownCounter used to record int64
 // measurements. It produces no telemetry.
 type Int64UpDownCounter struct{ embedded.Int64UpDownCounter }
@@ -205,6 +211,9 @@ type Int64UpDownCounter struct{ embedded.Int64UpDownCounter }
 // Add performs no operation.
 func (Int64UpDownCounter) Add(context.Context, int64, ...metric.AddOption) {}
 
+// Enabled performs no operation.
+func (Int64UpDownCounter) Enabled(context.Context) bool { return false }
+
 // Float64UpDownCounter is an OpenTelemetry UpDownCounter used to record
 // float64 measurements. It produces no telemetry.
 type Float64UpDownCounter struct{ embedded.Float64UpDownCounter }
@@ -212,6 +221,9 @@ type Float64UpDownCounter struct{ embedded.Float64UpDownCounter }
 // Add performs no operation.
 func (Float64UpDownCounter) Add(context.Context, float64, ...metric.AddOption) {}
 
+// Enabled performs no operation.
+func (Float64UpDownCounter) Enabled(context.Context) bool { return false }
+
 // Int64Histogram is an OpenTelemetry Histogram used to record int64
 // measurements. It produces no telemetry.
 type Int64Histogram struct{ embedded.Int64Histogram }
@@ -219,6 +231,9 @@ type Int64Histogram struct{ embedded.Int64Histogram }
 // Record performs no operation.
 func (Int64Histogram) Record(context.Context, int64, ...metric.RecordOption) {}
 
+// Enabled performs no operation.
+func (Int64Histogram) Enabled(context.Context) bool { return false }
+
 // Float64Histogram is an OpenTelemetry Histogram used to record float64
 // measurements. It produces no telemetry.
 type Float64Histogram struct{ embedded.Float64Histogram }
@@ -226,6 +241,9 @@ type Float64Histogram struct{ embedded.Float64Histogram }
 // Record performs no operation.
 func (Float64Histogram) Record(context.Context, float64, ...metric.RecordOption) {}
 
+// Enabled performs no operation.
+func (Float64Histogram) Enabled(context.Context) bool { return false }
+
 // Int64Gauge is an OpenTelemetry Gauge used to record instantaneous int64
 // measurements. It produces no telemetry.
 type Int64Gauge struct{ embedded.Int64Gauge }
@@ -233,6 +251,9 @@ type Int64Gauge struct{ embedded.Int64Gauge }
 // Record performs no operation.
 func (Int64Gauge) Record(context.Context, int64, ...metric.RecordOption) {}
 
+// Enabled performs no operation.
+func (Int64Gauge) Enabled(context.Context) bool { return false }
+
 // Float64Gauge is an OpenTelemetry Gauge used to record instantaneous float64
 // measurements. It produces no telemetry.
 type Float64Gauge struct{ embedded.Float64Gauge }
@@ -240,6 +261,9 @@ type Float64Gauge struct{ embedded.Float64Gauge }
 // Record performs no operation.
 func (Float64Gauge) Record(context.Context, float64, ...metric.RecordOption) {}
 
+// Enabled performs no operation.
+func (Float64Gauge) Enabled(context.Context) bool { return false }
+
 // Int64ObservableCounter is an OpenTelemetry ObservableCounter used to record
 // int64 measurements. It produces no telemetry.
 type Int64ObservableCounter struct {

metric/syncfloat64.go

@@ -25,6 +25,12 @@ type Float64Counter interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Add(ctx context.Context, incr float64, options ...AddOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Float64CounterConfig contains options for synchronous counter instruments that
@@ -78,6 +84,12 @@ type Float64UpDownCounter interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Add(ctx context.Context, incr float64, options ...AddOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Float64UpDownCounterConfig contains options for synchronous counter
@@ -131,6 +143,12 @@ type Float64Histogram interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Record(ctx context.Context, incr float64, options ...RecordOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Float64HistogramConfig contains options for synchronous histogram
@@ -189,6 +207,12 @@ type Float64Gauge interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Record(ctx context.Context, value float64, options ...RecordOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Float64GaugeConfig contains options for synchronous gauge instruments that

metric/syncint64.go

@@ -25,6 +25,12 @@ type Int64Counter interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Add(ctx context.Context, incr int64, options ...AddOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Int64CounterConfig contains options for synchronous counter instruments that
@@ -78,6 +84,12 @@ type Int64UpDownCounter interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Add(ctx context.Context, incr int64, options ...AddOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Int64UpDownCounterConfig contains options for synchronous counter
@@ -131,6 +143,12 @@ type Int64Histogram interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Record(ctx context.Context, incr int64, options ...RecordOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Int64HistogramConfig contains options for synchronous histogram instruments
@@ -189,6 +207,12 @@ type Int64Gauge interface {
 	// Use the WithAttributeSet (or, if performance is not a concern,
 	// the WithAttributes) option to include measurement attributes.
 	Record(ctx context.Context, value int64, options ...RecordOption)
+
+	// Enabled reports whether the instrument will process measurements for the given context.
+	//
+	// This function can be used in places where measuring an instrument
+	// would result in computationally expensive operations.
+	Enabled(context.Context) bool
 }
 
 // Int64GaugeConfig contains options for synchronous gauge instruments that