type Counter interface {
	// Observe records the state of the instrument.
	//
	// 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 int64, attrs ...attribute.KeyValue)

	instrument.Asynchronous
}

type Gauge interface {
	// Observe records the state of the instrument.
	//
	// 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 int64, attrs ...attribute.KeyValue)

	instrument.Asynchronous
}

type InstrumentProvider interface {
	// Counter creates an instrument for recording increasing values.
	Counter(name string, opts ...instrument.Option) (Counter, error)

	// UpDownCounter creates an instrument for recording changes of a value.
	UpDownCounter(name string, opts ...instrument.Option) (UpDownCounter, error)

	// Gauge creates an instrument for recording the current value.
	Gauge(name string, opts ...instrument.Option) (Gauge, error)
}

type UpDownCounter interface {
	// Observe records the state of the instrument.
	//
	// 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 int64, attrs ...attribute.KeyValue)

	instrument.Asynchronous
}