add tracer enabled status

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

tracer/memory/memory.go

@@ -46,6 +46,10 @@ func (s memoryStringer) String() string {
 	return s.s
 }
 
+func (t *Tracer) Enabled() bool {
+	return t.opts.Enabled
+}
+
 func (t *Tracer) Flush(_ context.Context) error {
 	return nil
 }

tracer/noop.go

@@ -20,6 +20,10 @@ func (t *noopTracer) Spans() []Span {
 
 var uuidNil = uuid.Nil.String()
 
+func (t *noopTracer) Enabled() bool {
+	return t.opts.Enabled
+}
+
 func (t *noopTracer) Start(ctx context.Context, name string, opts ...SpanOption) (context.Context, Span) {
 	options := NewSpanOptions(opts...)
 	span := &noopSpan{

tracer/options.go

@@ -142,6 +142,8 @@ type Options struct {
 	Name string
 	// ContextAttrFuncs contains funcs that provides tracing
 	ContextAttrFuncs []ContextAttrFunc
+	// Enabled specify trace status
+	Enabled bool
 }
 
 // Option func signature
@@ -181,6 +183,7 @@ func NewOptions(opts ...Option) Options {
 		Logger:           logger.DefaultLogger,
 		Context:          context.Background(),
 		ContextAttrFuncs: DefaultContextAttrFuncs,
+		Enabled:          true,
 	}
 	for _, o := range opts {
 		o(&options)
@@ -194,3 +197,10 @@ func Name(n string) Option {
 		o.Name = n
 	}
 }
+
+// Disabled disable tracer
+func Disabled(b bool) Option {
+	return func(o *Options) {
+		o.Enabled = !b
+	}
+}

tracer/tracer.go

@@ -51,6 +51,8 @@ type Tracer interface {
 	// Extract(ctx context.Context)
 	// Flush flushes spans
 	Flush(ctx context.Context) error
+	// Enabled returns tracer status
+	Enabled() bool
 }
 
 type Span interface {