meter = gmetric.GetGlobalProvider().Meter(gmetric.MeterOption{
    Instrument:        "github.com/gogf/gf/example/metric/basic",
    InstrumentVersion: "v1.0",
})

// MeterOption holds the creation option for a Meter.
type MeterOption struct {
	// Instrument is the instrumentation name to bind this Metric to a global MeterProvider.
	// This is an optional configuration for a metric.
	Instrument string

	// InstrumentVersion is the instrumentation version to bind this Metric to a global MeterProvider.
	// This is an optional configuration for a metric.
	InstrumentVersion string

	// Attributes holds the constant key-value pair description metadata for all metrics of Meter.
	// This is an optional configuration for a meter.
	Attributes Attributes
}

// Meter hold the functions for kinds of Metric creating.
type Meter interface {
	// Counter creates and returns a new Counter.
	Counter(name string, option MetricOption) (Counter, error)

	// UpDownCounter creates and returns a new UpDownCounter.
	UpDownCounter(name string, option MetricOption) (UpDownCounter, error)

	// Histogram creates and returns a new Histogram.
	Histogram(name string, option MetricOption) (Histogram, error)

	// ObservableCounter creates and returns a new ObservableCounter.
	ObservableCounter(name string, option MetricOption) (ObservableCounter, error)

	// ObservableUpDownCounter creates and returns a new ObservableUpDownCounter.
	ObservableUpDownCounter(name string, option MetricOption) (ObservableUpDownCounter, error)

	// ObservableGauge creates and returns a new ObservableGauge.
	ObservableGauge(name string, option MetricOption) (ObservableGauge, error)

	// MustCounter creates and returns a new Counter.
	// It panics if any error occurs.
	MustCounter(name string, option MetricOption) Counter

	// MustUpDownCounter creates and returns a new UpDownCounter.
	// It panics if any error occurs.
	MustUpDownCounter(name string, option MetricOption) UpDownCounter

	// MustHistogram creates and returns a new Histogram.
	// It panics if any error occurs.
	MustHistogram(name string, option MetricOption) Histogram

	// MustObservableCounter creates and returns a new ObservableCounter.
	// It panics if any error occurs.
	MustObservableCounter(name string, option MetricOption) ObservableCounter

	// MustObservableUpDownCounter creates and returns a new ObservableUpDownCounter.
	// It panics if any error occurs.
	MustObservableUpDownCounter(name string, option MetricOption) ObservableUpDownCounter

	// MustObservableGauge creates and returns a new ObservableGauge.
	// It panics if any error occurs.
	MustObservableGauge(name string, option MetricOption) ObservableGauge

	// RegisterCallback registers callback on certain metrics.
	// A callback is bound to certain component and version, it is called when the associated metrics are read.
	// Multiple callbacks on the same component and version will be called by their registered sequence.
	RegisterCallback(callback Callback, canBeCallbackMetrics ...ObservableMetric) error

	// MustRegisterCallback performs as RegisterCallback, but it panics if any error occurs.
	MustRegisterCallback(callback Callback, canBeCallbackMetrics ...ObservableMetric)
}

// MetricOption holds the basic options for creating a metric.
type MetricOption struct {
	// Help provides information about this Histogram.
	// This is an optional configuration for a metric.
	Help string

	// Unit is the unit for metric value.
	// This is an optional configuration for a metric.
	Unit string

	// Attributes holds the constant key-value pair description metadata for this metric.
	// This is an optional configuration for a metric.
	Attributes Attributes

	// Buckets defines the buckets into which observations are counted.
	// For Histogram metric only.
	// A histogram metric uses default buckets if no explicit buckets configured.
	Buckets []float64

	// Callback function for metric, which is called when metric value changes.
	// For observable metric only.
	// If an observable metric has either Callback attribute nor global callback configured, it does nothing.
	Callback MetricCallback
}

provider := otelmetric.MustProvider(metric.WithReader(reader))
provider.SetAsGlobal()
defer provider.Shutdown(ctx)

// Counter is a Metric that represents a single numerical value that can ever
// goes up.
type Counter interface {
	Metric
	CounterPerformer
}

// CounterPerformer performs operations for Counter metric.
type CounterPerformer interface {
	// Inc increments the counter by 1. Use Add to increment it by arbitrary
	// non-negative values.
	Inc(ctx context.Context, option ...Option)

	// Add adds the given value to the counter. It panics if the value is < 0.
	Add(ctx context.Context, increment float64, option ...Option)
}

// Metric models a single sample value with its metadata being exported.
type Metric interface {
	// Info returns the basic information of a Metric.
	Info() MetricInfo
}

// MetricInfo exports information of the Metric.
type MetricInfo interface {
	Key() string                // Key returns the unique string key of the metric.
	Name() string               // Name returns the name of the metric.
	Help() string               // Help returns the help description of the metric.
	Unit() string               // Unit returns the unit name of the metric.
	Type() MetricType           // Type returns the type of the metric.
	Attributes() Attributes     // Attributes returns the constant attribute slice of the metric.
	Instrument() InstrumentInfo // InstrumentInfo returns the instrument info of the metric.
}

// InstrumentInfo exports the instrument information of a metric.
type InstrumentInfo interface {
	Name() string    // Name returns the instrument name of the metric.
	Version() string // Version returns the instrument version of the metric.
}