Verify compliant metric API specification implementation: Meter

[MrAlias]

• Identify all the normative requirements, recommendations, and options the specification defines as comments to this issue
• Ensure the current metric API implementation is compliant with these normative requirements, recommendations, and options in those comments.

[MrAlias]

Meter SHOULD NOT be responsible for the configuration. This should be the responsibility of the MeterProvider instead.

This is an implementation of the API concern, but we do comply FWIW.

[MrAlias]

The Meter MUST provide functions to create new Instruments:

• Create a new Counter
• Create a new Asynchronous Counter
• Create a new Histogram]
• Create a new Asynchronous Gauge
• Create a new UpDownCounter
• Create a new Asynchronous UpDownCounter

With the resolution of #3454 our API is compliant with this requirement.

opentelemetry-go/metric/meter.go

Lines 43 to 110 in a54167d

	type Meter interface {
	// Int64Counter returns a new instrument identified by name and configured
	// with options. The instrument is used to synchronously record increasing
	// int64 measurements during a computational operation.
	Int64Counter(name string, options ...instrument.Option) (syncint64.Counter, error)
	// Int64UpDownCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// int64 measurements during a computational operation.
	Int64UpDownCounter(name string, options ...instrument.Option) (syncint64.UpDownCounter, error)
	// Int64Histogram returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// the distribution of int64 measurements during a computational operation.
	Int64Histogram(name string, options ...instrument.Option) (syncint64.Histogram, error)
	// Int64ObservableCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// increasing int64 measurements once per a measurement collection cycle.
	Int64ObservableCounter(name string, options ...instrument.Option) (asyncint64.Counter, error)
	// Int64ObservableUpDownCounter returns a new instrument identified by name
	// and configured with options. The instrument is used to asynchronously
	// record int64 measurements once per a measurement collection cycle.
	Int64ObservableUpDownCounter(name string, options ...instrument.Option) (asyncint64.UpDownCounter, error)
	// Int64ObservableGauge returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// instantaneous int64 measurements once per a measurement collection
	// cycle.
	Int64ObservableGauge(name string, options ...instrument.Option) (asyncint64.Gauge, error)
	// Float64Counter returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// increasing float64 measurements during a computational operation.
	Float64Counter(name string, options ...instrument.Option) (syncfloat64.Counter, error)
	// Float64UpDownCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// float64 measurements during a computational operation.
	Float64UpDownCounter(name string, options ...instrument.Option) (syncfloat64.UpDownCounter, error)
	// Float64Histogram returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// the distribution of float64 measurements during a computational
	// operation.
	Float64Histogram(name string, options ...instrument.Option) (syncfloat64.Histogram, error)
	// Float64ObservableCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// increasing float64 measurements once per a measurement collection cycle.
	Float64ObservableCounter(name string, options ...instrument.Option) (asyncfloat64.Counter, error)
	// Float64ObservableUpDownCounter returns a new instrument identified by
	// name and configured with options. The instrument is used to
	// asynchronously record float64 measurements once per a measurement
	// collection cycle.
	Float64ObservableUpDownCounter(name string, options ...instrument.Option) (asyncfloat64.UpDownCounter, error)
	// Float64ObservableGauge returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// instantaneous float64 measurements once per a measurement collection
	// cycle.
	Float64ObservableGauge(name string, options ...instrument.Option) (asyncfloat64.Gauge, error)
	// RegisterCallback registers f to be called during the collection of a
	// measurement cycle.
	//
	// If Unregister of the returned Registration is called, f needs to be
	// unregistered and not called during collection.
	//
	// The instruments f is registered with are the only instruments that f may
	// observe values for.
	//
	// If no instruments are passed, f should not be registered nor called
	// during collection.
	RegisterCallback(instruments []instrument.Asynchronous, f func(context.Context)) (Registration, error)
	}

[MrAlias]

Every normative clause from the MeterProvider section of the v1.16.0 specification has been identified and our API has been validated that it complies. Closing.