Allocate SpanContext to deal with lifetime issues

raw.go

@@ -10,7 +10,7 @@ import (
 type RawSpan struct {
 	// The RawSpan embeds its SpanContext. Those recording the RawSpan
 	// should also record the contents of its SpanContext.
-	SpanContext
+	*SpanContext
 
 	// The SpanID of this SpanContext's first intra-trace reference (i.e.,
 	// "parent"), or 0 if there is no parent.

recorder_test.go

@@ -12,7 +12,7 @@ func TestInMemoryRecorderSpans(t *testing.T) {
 	recorder := NewInMemoryRecorder()
 	var apiRecorder SpanRecorder = recorder
 	span := RawSpan{
-		SpanContext: SpanContext{},
+		SpanContext: &SpanContext{},
 		Operation:   "test-span",
 		Start:       time.Now(),
 		Duration:    -1,

span.go

@@ -51,7 +51,9 @@ func (s *spanImpl) reset() {
 	// a buffer pool when GC considers them unreachable, which should ease
 	// some of the load. Hard to say how quickly that would be in practice
 	// though.
-	s.raw = RawSpan{}
+	s.raw = RawSpan{
+		SpanContext: &SpanContext{},
+	}
 }
 
 func (s *spanImpl) SetOperationName(operationName string) opentracing.Span {
@@ -153,7 +155,7 @@ func (s *spanImpl) Tracer() opentracing.Tracer {
 }
 
 func (s *spanImpl) Context() opentracing.SpanContext {
-	return &s.raw.SpanContext
+	return s.raw.SpanContext
 }
 
 func (s *spanImpl) Operation() string {

tracer.go

@@ -133,7 +133,11 @@ func (t *tracerImpl) getSpan() *spanImpl {
 		sp.reset()
 		return sp
 	}
-	return &spanImpl{}
+	return &spanImpl{
+		raw: RawSpan{
+			SpanContext: &SpanContext{},
+		},
+	}
 }
 
 func (t *tracerImpl) StartSpanWithOptions(