Add Finish to Span destructor

Signed-off-by: Isaac Hier <ihier@uber.com>

Author: Isaac Hier

src/jaegertracing/Span.cpp

@@ -43,6 +43,10 @@ void Span::FinishWithOptions(
     std::shared_ptr<const Tracer> tracer;
     {
         std::lock_guard<std::mutex> lock(_mutex);
+        if (isFinished()) {
+            // Already finished, so return immediately.
+            return;
+        }
         _duration = finishSpanOptions.finish_steady_timestamp - _startTime;
         tracer = _tracer;
     }

src/jaegertracing/Span.h

@@ -76,6 +76,8 @@ class Span : public opentracing::Span {
         return *this;
     }
 
+    ~Span() { Finish(); }
+
     void swap(Span& span)
     {
         using std::swap;

src/jaegertracing/TracerTest.cpp

@@ -78,6 +78,8 @@ TEST(Tracer, testTracer)
     const SpanContext debugCtx(TraceID(),
                                0,
                                0,
+                               static_cast<unsigned char>(
+                                   SpanContext::Flag::kSampled) |
                                static_cast<unsigned char>(
                                    SpanContext::Flag::kDebug),
                                SpanContext::StrMap({
@@ -122,6 +124,8 @@ TEST(Tracer, testTracer)
         tracer->StartSpanWithOptions(
             "test-span-with-debug-parent", options).release()));
 
+    span.reset();
+
     opentracing::Tracer::InitGlobal(opentracing::MakeNoopTracer());
 }