Adding locks where context is accessed

This commit addresses data race issues where span.context is accessed without locks in methods which can be called concurrently with method setBaggageItem which modifies context

Per issue #526

Signed-off-by: Keerthana Selvakumar <keerukeerthana8@gmail.com>

span.go

@@ -120,8 +120,8 @@ func (s *Span) setTagInternal(key string, value interface{}, lock bool) opentrac
 
 // SpanContext returns span context
 func (s *Span) SpanContext() SpanContext {
-	s.Lock()
-	defer s.Unlock()
+	s.RLock()
+	defer s.RUnlock()
 	return s.context
 }
 
@@ -345,7 +345,7 @@ func (s *Span) FinishWithOptions(options opentracing.FinishOptions) {
 		decision := s.tracer.sampler.OnFinishSpan(s)
 		s.applySamplingDecision(decision, true)
 	}
-	if s.context.IsSampled() {
+	if s.SpanContext().IsSampled() {
 		s.Lock()
 		s.fixLogsIfDropped()
 		if len(options.LogRecords) > 0 || len(options.BulkLogData) > 0 {
@@ -366,8 +366,8 @@ func (s *Span) FinishWithOptions(options opentracing.FinishOptions) {
 
 // Context implements opentracing.Span API
 func (s *Span) Context() opentracing.SpanContext {
-	s.Lock()
-	defer s.Unlock()
+	s.RLock()
+	defer s.RUnlock()
 	return s.context
 }
 
@@ -427,10 +427,10 @@ func (s *Span) serviceName() string {
 
 func (s *Span) applySamplingDecision(decision SamplingDecision, lock bool) {
 	if !decision.Retryable {
-		s.context.samplingState.setFinal()
+		s.SpanContext().samplingState.setFinal()
 	}
 	if decision.Sample {
-		s.context.samplingState.setSampled()
+		s.SpanContext().samplingState.setSampled()
 		if len(decision.Tags) > 0 {
 			if lock {
 				s.Lock()
@@ -445,12 +445,12 @@ func (s *Span) applySamplingDecision(decision SamplingDecision, lock bool) {
 
 // Span can be written to if it is sampled or the sampling decision has not been finalized.
 func (s *Span) isWriteable() bool {
-	state := s.context.samplingState
+	state := s.SpanContext().samplingState
 	return !state.isFinal() || state.isSampled()
 }
 
 func (s *Span) isSamplingFinalized() bool {
-	return s.context.samplingState.isFinal()
+	return s.SpanContext().samplingState.isFinal()
 }
 
 // setSamplingPriority returns true if the flag was updated successfully, false otherwise.
@@ -469,6 +469,8 @@ func setSamplingPriority(s *Span, value interface{}) bool {
 	if !ok {
 		return false
 	}
+	s.RLock()
+	defer s.RUnlock()
 	if val == 0 {
 		s.context.samplingState.unsetSampled()
 		s.context.samplingState.setFinal()

span_test.go

@@ -363,7 +363,6 @@ func TestSpan_References(t *testing.T) {
 }
 
 func TestSpanContextRaces(t *testing.T) {
-	t.Skip("Skipped: test will panic with -race, see https://github.com/jaegertracing/jaeger-client-go/issues/526")
 	tracer, closer := NewTracer("test", NewConstSampler(true), NewNullReporter())
 	defer closer.Close()