fix: dd.p parsing

examples/http-server/common/tracingutil.h

@@ -16,7 +16,12 @@ class HeaderWriter final : public datadog::tracing::DictWriter {
   explicit HeaderWriter(httplib::Headers& headers) : headers_(headers) {}
 
   void set(std::string_view key, std::string_view value) override {
-    headers_.emplace(key, value);
+    auto found = headers_.find(std::string(key));
+    if (found == headers_.cend()) {
+      headers_.emplace(key, value);
+    } else {
+      found->second = value;
+    }
   }
 };
 

examples/http-server/proxy/proxy.cpp

@@ -43,43 +43,44 @@ int main() {
 
   dd::Tracer tracer{*finalized_config};
 
-  httplib::Client upstream_client("server", 80);
+  httplib::Client upstream_client("server", 8080);
 
   // Configure the HTTP server.
   auto forward_handler = [&tracer, &upstream_client](
                              const httplib::Request& req,
                              httplib::Response& res) {
-    auto span = tracer.create_span();
-    span.set_name("forward.request");
-    span.set_resource_name(req.method + " " + req.path);
-    span.set_tag("network.origin.ip", req.remote_addr);
-    span.set_tag("network.origin.port", std::to_string(req.remote_port));
-    span.set_tag("http.url_details.path", req.target);
-    span.set_tag("http.route", req.path);
-    span.set_tag("http.method", req.method);
+    tracingutil::HeaderReader reader(req.headers);
+    auto span = tracer.extract_or_create_span(reader);
+    span->set_name("forward.request");
+    span->set_resource_name(req.method + " " + req.path);
+    span->set_tag("network.origin.ip", req.remote_addr);
+    span->set_tag("network.origin.port", std::to_string(req.remote_port));
+    span->set_tag("http.url_details.path", req.target);
+    span->set_tag("http.route", req.path);
+    span->set_tag("http.method", req.method);
 
     httplib::Error er;
     httplib::Request forward_request(req);
     forward_request.path = req.target;
 
     tracingutil::HeaderWriter writer(forward_request.headers);
-    span.inject(writer);
+    span->inject(writer);
 
     upstream_client.send(forward_request, res, er);
     if (er != httplib::Error::Success) {
       res.status = 500;
-      span.set_error_message(httplib::to_string(er));
+      span->set_error_message(httplib::to_string(er));
       std::cerr << "Error occurred while proxying request: " << req.target
                 << "\n";
     } else {
       tracingutil::HeaderReader reader(res.headers);
-      auto status = span.read_sampling_delegation_response(reader);
+      auto status = span->read_sampling_delegation_response(reader);
       if (auto error = status.if_error()) {
         std::cerr << error << "\n";
       }
     }
 
-    span.set_tag("http.status_code", std::to_string(res.status));
+    span->set_tag("http.status_code", std::to_string(res.status));
   };
 
   httplib::Server server;

src/datadog/tags.cpp

@@ -1,7 +1,5 @@
 #include "tags.h"
 
-#include "string_util.h"
-
 namespace datadog {
 namespace tracing {
 namespace tags {
@@ -32,11 +30,10 @@ const std::string process_id = "process_id";
 const std::string language = "language";
 const std::string runtime_id = "runtime-id";
 const std::string sampling_decider = "_dd.is_sampling_decider";
+const std::string w3c_parent_id = "_dd.parent_id";
 
 }  // namespace internal
 
-bool is_internal(StringView tag_name) { return starts_with(tag_name, "_dd."); }
-
 }  // namespace tags
 }  // namespace tracing
 }  // namespace datadog

src/datadog/tags.h

@@ -5,6 +5,7 @@
 
 #include <string>
 
+#include "string_util.h"
 #include "string_view.h"
 
 namespace datadog {
@@ -36,11 +37,14 @@ extern const std::string process_id;
 extern const std::string language;
 extern const std::string runtime_id;
 extern const std::string sampling_decider;
+extern const std::string w3c_parent_id;
 }  // namespace internal
 
 // Return whether the specified `tag_name` is reserved for use internal to this
 // library.
-bool is_internal(StringView tag_name);
+inline bool is_internal(StringView tag_name) {
+  return starts_with(tag_name, "_dd.");
+}
 
 }  // namespace tags
 }  // namespace tracing

src/datadog/tracer.cpp

@@ -278,7 +278,7 @@ Expected<Span> Tracer::extract_span(const DictReader& reader,
   }
 
   if (datadog_w3c_parent_id) {
-    span_data->tags["_dd.parent_id"] = *datadog_w3c_parent_id;
+    span_data->tags[tags::internal::w3c_parent_id] = *datadog_w3c_parent_id;
   }
 
   Optional<SamplingDecision> sampling_decision;

src/datadog/w3c_propagation.cpp

@@ -228,7 +228,7 @@ void parse_datadog_tracestate(ExtractedData& result, StringView datadog_value) {
         continue;
       }
 
-      const auto maybe_id = parse_int(value, 16);
+      const auto maybe_id = parse_uint64(value, 16);
       if (!maybe_id || *maybe_id == 0) {
         // chaff!
         pair_begin = pair_end == end ? end : pair_end + 1;