trace

type B3 struct {
	SingleHeader bool
}

type Decision struct {
	// Sampled is set true if the span should be sampled.
	Sampled bool

	// Attributes provides insight into Sample	r's decision process.
	// It could be empty slice or nil if no attributes are recorded by the sampler.
	Attributes []core.KeyValue
}

type EndConfig struct {
	EndTime time.Time
}

type EndOption func(*EndConfig)

type ErrorConfig struct {
	Timestamp  time.Time
	StatusCode codes.Code
}

type ErrorOption func(*ErrorConfig)

type Link struct {
	core.SpanContext
	Attributes []core.KeyValue
}

type NoopProvider struct{}

type NoopSpan struct {
}

type NoopTracer struct{}

type Provider interface {
	// Tracer creates a named tracer that implements Tracer interface.
	// If the name is an empty string then provider uses default name.
	Tracer(name string) Tracer
}

type Sampler interface {
	// ShouldSample returns a Decision that contains a decision whether to sample
	// or not sample the span to be created. Decision is based on a Sampler specific
	// algorithm that takes into account one or more input parameters.
	ShouldSample(
		sc core.SpanContext,
		remote bool,
		traceID core.TraceID,
		spanID core.SpanID,
		spanName string,
		spanKind SpanKind,
		attributes []core.KeyValue,
		links []Link,
	) Decision

	// Description returns of the sampler. It contains its name or short description
	// and its configured properties.
	// For example 'ProbabilitySampler:{0.00001}'
	Description() string
}

type Span interface {
	// Tracer returns tracer used to create this span. Tracer cannot be nil.
	Tracer() Tracer

	// End completes the span. No updates are allowed to span after it
	// ends. The only exception is setting status of the span.
	End(options ...EndOption)

	// AddEvent adds an event to the span.
	AddEvent(ctx context.Context, name string, attrs ...core.KeyValue)
	// AddEventWithTimestamp adds an event with a custom timestamp
	// to the span.
	AddEventWithTimestamp(ctx context.Context, timestamp time.Time, name string, attrs ...core.KeyValue)

	// IsRecording returns true if the span is active and recording events is enabled.
	IsRecording() bool

	// RecordError records an error as a span event.
	RecordError(ctx context.Context, err error, opts ...ErrorOption)

	// SpanContext returns span context of the span. Returned SpanContext is usable
	// even after the span ends.
	SpanContext() core.SpanContext

	// SetStatus sets the status of the span in the form of a code
	// and a message.  SetStatus overrides the value of previous
	// calls to SetStatus on the Span.
	//
	// The default span status is OK, so it is not necessary to
	// explicitly set an OK status on successful Spans unless it
	// is to add an OK message or to override a previous status on the Span.
	SetStatus(codes.Code, string)

	// SetName sets the name of the span.
	SetName(name string)

	// Set span attributes
	SetAttributes(...core.KeyValue)
}

type SpanKind int

type StartConfig struct {
	Attributes []core.KeyValue
	StartTime  time.Time
	Links      []Link
	Record     bool
	NewRoot    bool
	SpanKind   SpanKind
}

type StartOption func(*StartConfig)

type TraceContext struct{}

type Tracer interface {
	// Start a span.
	Start(ctx context.Context, spanName string, opts ...StartOption) (context.Context, Span)

	// WithSpan wraps the execution of the fn function with a span.
	// It starts a new span, sets it as an active span in the context,
	// executes the fn function and closes the span before returning the result of fn.
	WithSpan(
		ctx context.Context,
		spanName string,
		fn func(ctx context.Context) error,
		opts ...StartOption,
	) error
}