From fa16a331137a68ff7dd8f7600bbca2ccd7ddef3f Mon Sep 17 00:00:00 2001
From: Chris Goller <goller@gmail.com>
Date: Wed, 20 Nov 2019 09:39:27 -0600
Subject: [PATCH 1/2] Add jaeger-debug-id as a tag

If the trace was started with a debugID, adding jaeger-debug-id
as tag ensures that the trace will be sampled in the "debug" mode.

Additionally, the root span will have this ID as a searchable tag.

Resolves: #136

Signed-off-by: Chris Goller <goller@gmail.com>
---
 src/jaegertracing/Tracer.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/jaegertracing/Tracer.cpp b/src/jaegertracing/Tracer.cpp
index 331d44b0..1fb6087a 100644
--- a/src/jaegertracing/Tracer.cpp
+++ b/src/jaegertracing/Tracer.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include "jaegertracing/Tag.h"
 #include "jaegertracing/Tracer.h"
 #include "jaegertracing/Reference.h"
 #include "jaegertracing/TraceID.h"
@@ -85,6 +86,7 @@ Tracer::StartSpanWithOptions(string_view operationName,
                 flags |=
                     (static_cast<unsigned char>(SpanContext::Flag::kSampled) |
                      static_cast<unsigned char>(SpanContext::Flag::kDebug));
+                samplerTags.push_back(Tag(kJaegerDebugHeader, parent->debugID()));
             }
             else {
                 const auto samplingStatus =

From 7d815276ed2ba925c2de926c61de83e3a9090f5f Mon Sep 17 00:00:00 2001
From: Chris Goller <goller@gmail.com>
Date: Fri, 22 Nov 2019 23:28:22 -0600
Subject: [PATCH 2/2] Add test for jaeger-debug-id correlation tag creation

Signed-off-by: Chris Goller <goller@gmail.com>
---
 src/jaegertracing/TracerTest.cpp | 44 +++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/src/jaegertracing/TracerTest.cpp b/src/jaegertracing/TracerTest.cpp
index 07291052..4a5a0057 100644
--- a/src/jaegertracing/TracerTest.cpp
+++ b/src/jaegertracing/TracerTest.cpp
@@ -118,7 +118,7 @@ absTimeDiff(const typename ClockType::time_point& lhs,
 TEST(Tracer, testTracer)
 {
     {
-    
+
     const auto handle = testutils::TracerUtil::installGlobalTracer();
     const auto tracer =
         std::static_pointer_cast<Tracer>(opentracing::Tracer::Global());
@@ -269,6 +269,48 @@ TEST(Tracer, testTracer)
     //std::this_thread::sleep_for(std::chrono::milliseconds(10000));
 }
 
+TEST(Tracer, testDebugSpan)
+{
+    const auto handle = testutils::TracerUtil::installGlobalTracer();
+    const auto tracer =
+        std::static_pointer_cast<Tracer>(opentracing::Tracer::Global());
+
+    // we force span sampling and require debug-id as the extracted
+    // jaeger-debug-id correlation value.
+    std::string correlationID = "debug-id";
+
+    StrMap headers ={
+        {kJaegerDebugHeader, correlationID},
+    };
+
+    WriterMock<opentracing::HTTPHeadersWriter> headerWriter(headers);
+    ReaderMock<opentracing::HTTPHeadersReader> headerReader(headers);
+
+    const FakeSpanContext fakeCtx;
+    tracer->Inject(fakeCtx, headerWriter);
+    auto ext = tracer->Extract(headerReader);
+
+    const SpanContext* ctx = dynamic_cast<SpanContext*>(ext->release());
+    opentracing::StartSpanOptions opts;
+    opts.references.emplace_back(opentracing::SpanReferenceType::ChildOfRef, ctx);
+
+    auto otspan = tracer->StartSpanWithOptions("name", opts);
+    // downcast to jaegertracing span implementation so we can inspect tags
+    const std::unique_ptr<Span> span(dynamic_cast<Span*>(otspan.release()));
+
+    const auto& spanTags = span->tags();
+    auto spanItr =
+        std::find_if(std::begin(spanTags), std::end(spanTags), [](const Tag& tag) {
+            return tag.key() == kJaegerDebugHeader;
+        });
+    ASSERT_NE(std::end(spanTags), spanItr);
+    ASSERT_TRUE(spanItr->value().is<std::string>());
+    ASSERT_EQ(spanItr->value().get<std::string>(), correlationID);
+
+    tracer->Close();
+    opentracing::Tracer::InitGlobal(opentracing::MakeNoopTracer());
+}
+
 TEST(Tracer, testConstructorFailure)
 {
     Config config;