Create child spans for mixer check calls

src/envoy/http/mixer/control.cc

@@ -32,7 +32,8 @@ Control::Control(const Config& config, Upstream::ClusterManager& cm,
                  config_.config_pb().transport().stats_update_interval(),
                  [this](::istio::mixerclient::Statistics* stat) -> bool {
                    return GetStats(stat);
-                 }) {
+                 }),
+      random_(random) {
   ::istio::control::http::Controller::Options options(config_.config_pb());
 
   Utils::CreateEnvironment(dispatcher, random, *check_client_factory_,
@@ -43,7 +44,8 @@ Control::Control(const Config& config, Upstream::ClusterManager& cm,
 
 Utils::CheckTransport::Func Control::GetCheckTransport(
     const HeaderMap* headers) {
-  return Utils::CheckTransport::GetFunc(*check_client_factory_, headers);
+  return Utils::CheckTransport::GetFunc(*check_client_factory_, random_,
+                                        headers);
 }
 
 // Call controller to get statistics.

src/envoy/http/mixer/control.h

@@ -56,6 +56,8 @@ class Control final : public ThreadLocal::ThreadLocalObject {
   Grpc::AsyncClientFactoryPtr report_client_factory_;
   // The stats object.
   Utils::MixerStatsObject stats_obj_;
+  // Random number generator for remote check span id.
+  Runtime::RandomGenerator& random_;
 };
 
 }  // namespace Mixer

src/envoy/utils/grpc_transport.cc

@@ -50,10 +50,11 @@ template <class RequestType, class ResponseType>
 GrpcTransport<RequestType, ResponseType>::GrpcTransport(
     Grpc::AsyncClientPtr async_client, const RequestType &request,
     const Http::HeaderMap *headers, ResponseType *response,
-    istio::mixerclient::DoneFunc on_done)
+    Runtime::RandomGenerator &random, istio::mixerclient::DoneFunc on_done)
     : async_client_(std::move(async_client)),
       headers_(headers),
       response_(response),
+      random_(random),
       on_done_(on_done),
       request_(async_client_->send(
           descriptor(), request, *this, Tracing::NullSpan::instance(),
@@ -69,10 +70,11 @@ void GrpcTransport<RequestType, ResponseType>::onCreateInitialMetadata(
 
   CopyHeaderEntry(headers_->RequestId(), kRequestId, metadata);
   CopyHeaderEntry(headers_->XB3TraceId(), kB3TraceId, metadata);
-  CopyHeaderEntry(headers_->XB3SpanId(), kB3SpanId, metadata);
-  CopyHeaderEntry(headers_->XB3ParentSpanId(), kB3ParentSpanId, metadata);
   CopyHeaderEntry(headers_->XB3Sampled(), kB3Sampled, metadata);
   CopyHeaderEntry(headers_->XB3Flags(), kB3Flags, metadata);
+  // Create a child span for mixer call.
+  CopyHeaderEntry(headers_->XB3SpanId(), kB3ParentSpanId, metadata);
+  metadata.addReferenceKey(kB3SpanId, Hex::uint64ToHex(random_.random()));
 
   // This one is NOT inline, need to do linar search.
   CopyHeaderEntry(headers_->get(kOtSpanContext), kOtSpanContext, metadata);
@@ -107,12 +109,14 @@ void GrpcTransport<RequestType, ResponseType>::Cancel() {
 template <class RequestType, class ResponseType>
 typename GrpcTransport<RequestType, ResponseType>::Func
 GrpcTransport<RequestType, ResponseType>::GetFunc(
-    Grpc::AsyncClientFactory &factory, const Http::HeaderMap *headers) {
-  return [&factory, headers](const RequestType &request, ResponseType *response,
-                             istio::mixerclient::DoneFunc on_done)
+    Grpc::AsyncClientFactory &factory, Runtime::RandomGenerator &random,
+    const Http::HeaderMap *headers) {
+  return [&factory, &random, headers](const RequestType &request,
+                                      ResponseType *response,
+                                      istio::mixerclient::DoneFunc on_done)
              -> istio::mixerclient::CancelFunc {
     auto transport = new GrpcTransport<RequestType, ResponseType>(
-        factory.create(), request, headers, response, on_done);
+        factory.create(), request, headers, response, random, on_done);
     return [transport]() { transport->Cancel(); };
   };
 }
@@ -137,9 +141,11 @@ const google::protobuf::MethodDescriptor &ReportTransport::descriptor() {
 
 // explicitly instantiate CheckTransport and ReportTransport
 template CheckTransport::Func CheckTransport::GetFunc(
-    Grpc::AsyncClientFactory &factory, const Http::HeaderMap *headers);
+    Grpc::AsyncClientFactory &factory, Runtime::RandomGenerator &random,
+    const Http::HeaderMap *headers);
 template ReportTransport::Func ReportTransport::GetFunc(
-    Grpc::AsyncClientFactory &factory, const Http::HeaderMap *headers);
+    Grpc::AsyncClientFactory &factory, Runtime::RandomGenerator &random,
+    const Http::HeaderMap *headers);
 
 }  // namespace Utils
 }  // namespace Envoy

src/envoy/utils/grpc_transport.h

@@ -39,10 +39,12 @@ class GrpcTransport : public Grpc::TypedAsyncRequestCallbacks<ResponseType>,
       istio::mixerclient::DoneFunc on_done)>;
 
   static Func GetFunc(Grpc::AsyncClientFactory& factory,
+                      Runtime::RandomGenerator& random,
                       const Http::HeaderMap* headers = nullptr);
 
   GrpcTransport(Grpc::AsyncClientPtr async_client, const RequestType& request,
                 const Http::HeaderMap* headers, ResponseType* response,
+                Runtime::RandomGenerator& random,
                 istio::mixerclient::DoneFunc on_done);
 
   // Grpc::AsyncRequestCallbacks<ResponseType>
@@ -62,6 +64,7 @@ class GrpcTransport : public Grpc::TypedAsyncRequestCallbacks<ResponseType>,
   Grpc::AsyncClientPtr async_client_;
   const Http::HeaderMap* headers_;
   ResponseType* response_;
+  Runtime::RandomGenerator& random_;
   ::istio::mixerclient::DoneFunc on_done_;
   Grpc::AsyncRequest* request_{};
 };

src/envoy/utils/mixer_control.cc

@@ -61,8 +61,10 @@ void CreateEnvironment(Event::Dispatcher &dispatcher,
                        Grpc::AsyncClientFactory &check_client_factory,
                        Grpc::AsyncClientFactory &report_client_factory,
                        ::istio::mixerclient::Environment *env) {
-  env->check_transport = CheckTransport::GetFunc(check_client_factory, nullptr);
-  env->report_transport = ReportTransport::GetFunc(report_client_factory);
+  env->check_transport =
+      CheckTransport::GetFunc(check_client_factory, random, nullptr);
+  env->report_transport =
+      ReportTransport::GetFunc(report_client_factory, random);
 
   env->timer_create_func = [&dispatcher](std::function<void()> timer_cb)
       -> std::unique_ptr<::istio::mixerclient::Timer> {