feat: allow ignore by condition (#32)

Signed-off-by: rogerogers <rogers@rogerogers.com>

tracing/middleware.go

@@ -129,6 +129,10 @@ func ClientMiddleware(opts ...Option) client.Middleware {
 
 func ServerMiddleware(cfg *Config) app.HandlerFunc {
 	return func(ctx context.Context, c *app.RequestContext) {
+		if cfg.shouldIgnore(ctx, c) {
+			c.Next(ctx)
+			return
+		}
 		// get tracer carrier
 		tc := internal.TraceCarrierFromContext(ctx)
 		if tc == nil {

tracing/options.go

@@ -40,6 +40,8 @@ func (fn option) apply(cfg *Config) {
 	fn(cfg)
 }
 
+type ConditionFunc func(ctx context.Context, c *app.RequestContext) bool
+
 type Config struct {
 	tracer trace.Tracer
 	meter  metric.Meter
@@ -54,6 +56,7 @@ type Config struct {
 	recordSourceOperation bool
 
 	customResponseHandler app.HandlerFunc
+	shouldIgnore          ConditionFunc
 }
 
 func newConfig(opts []Option) *Config {
@@ -95,6 +98,9 @@ func defaultConfig() *Config {
 			}
 			return route
 		},
+		shouldIgnore: func(ctx context.Context, c *app.RequestContext) bool {
+			return false
+		},
 	}
 }
 
@@ -132,3 +138,10 @@ func WithServerHttpRouteFormatter(serverHttpRouteFormatter func(c *app.RequestCo
 		cfg.serverHttpRouteFormatter = serverHttpRouteFormatter
 	})
 }
+
+// WithShouldIgnore allows you to define the condition for enabling distributed tracing
+func WithShouldIgnore(condition ConditionFunc) Option {
+	return option(func(cfg *Config) {
+		cfg.shouldIgnore = condition
+	})
+}

tracing/tracer_server.go

@@ -73,14 +73,20 @@ func (s *serverTracer) createMeasures() {
 	s.histogramRecorder[ServerLatency] = serverLatencyMeasure
 }
 
-func (s *serverTracer) Start(ctx context.Context, _ *app.RequestContext) context.Context {
+func (s *serverTracer) Start(ctx context.Context, c *app.RequestContext) context.Context {
+	if s.config.shouldIgnore(ctx, c) {
+		return ctx
+	}
 	tc := &internal.TraceCarrier{}
 	tc.SetTracer(s.config.tracer)
 
 	return internal.WithTraceCarrier(ctx, tc)
 }
 
 func (s *serverTracer) Finish(ctx context.Context, c *app.RequestContext) {
+	if s.config.shouldIgnore(ctx, c) {
+		return
+	}
 	// trace carrier from context
 	tc := internal.TraceCarrierFromContext(ctx)
 	if tc == nil {