api: remove json_fwd.h from the public API (#146)

Author: dmehala

BUILD.bazel

@@ -28,7 +28,6 @@ cc_library(
       "src/datadog/runtime_id.cpp",
       "src/datadog/span.cpp",
       "src/datadog/span_data.cpp",
-      "src/datadog/span_defaults.cpp",
       "src/datadog/span_matcher.cpp",
       "src/datadog/span_sampler_config.cpp",
       "src/datadog/span_sampler.cpp",
@@ -56,6 +55,7 @@ cc_library(
       "src/datadog/glob.h",
       "src/datadog/hex.h",
       "src/datadog/json.hpp",
+      "src/datadog/json_serializer.h",
       "src/datadog/limiter.h",
       "src/datadog/metrics.h",
       "src/datadog/msgpack.h",
@@ -88,7 +88,6 @@ cc_library(
       "include/datadog/http_client.h",
       "include/datadog/id_generator.h",
       "include/datadog/injection_options.h",
-      "include/datadog/json_fwd.hpp",
       "include/datadog/logger.h",
       "include/datadog/null_collector.h",
       "include/datadog/optional.h",

CMakeLists.txt

@@ -114,7 +114,6 @@ target_sources(dd_trace_cpp-objects
     src/datadog/runtime_id.cpp
     src/datadog/span.cpp
     src/datadog/span_data.cpp
-    src/datadog/span_defaults.cpp
     src/datadog/span_matcher.cpp
     src/datadog/span_sampler_config.cpp
     src/datadog/span_sampler.cpp

include/datadog/environment.h

@@ -17,8 +17,6 @@
 #include <datadog/optional.h>
 #include <datadog/string_view.h>
 
-#include "json_fwd.hpp"
-
 namespace datadog {
 namespace tracing {
 namespace environment {
@@ -80,7 +78,7 @@ StringView name(Variable variable);
 // `nullopt` if that variable is not set in the environment.
 Optional<StringView> lookup(Variable variable);
 
-nlohmann::json to_json();
+std::string to_json();
 
 }  // namespace environment
 }  // namespace tracing

include/datadog/json_fwd.hpp

@@ -7,8 +7,6 @@
 #include <string>
 #include <unordered_map>
 
-#include "json_fwd.hpp"
-
 namespace datadog {
 namespace tracing {
 
@@ -21,9 +19,12 @@ struct SpanDefaults {
   std::unordered_map<std::string, std::string> tags;
 };
 
-nlohmann::json to_json(const SpanDefaults&);
-
-bool operator==(const SpanDefaults&, const SpanDefaults&);
+inline bool operator==(const SpanDefaults& lhs, const SpanDefaults& rhs) {
+#define EQ(FIELD) lhs.FIELD == rhs.FIELD
+  return EQ(service) && EQ(service_type) && EQ(environment) && EQ(version) &&
+         EQ(name) && EQ(tags);
+#undef EQ
+}
 
 }  // namespace tracing
 }  // namespace datadog

include/datadog/span_defaults.h

@@ -13,7 +13,6 @@
 #include <unordered_map>
 
 #include "expected.h"
-#include "json_fwd.hpp"
 
 namespace datadog {
 namespace tracing {
@@ -29,9 +28,6 @@ struct SpanMatcher {
   std::unordered_map<std::string, std::string> tags;
 
   bool match(const SpanData&) const;
-  nlohmann::json to_json() const;
-
-  static Expected<SpanMatcher> from_json(const nlohmann::json&);
 
   bool operator==(const SpanMatcher& other) const {
     return (service == other.service && name == other.name &&

include/datadog/span_matcher.h

@@ -24,8 +24,6 @@ struct TraceSamplerRule final {
   Rate rate;
   SpanMatcher matcher;
   SamplingMechanism mechanism;
-
-  nlohmann::json to_json() const;
 };
 
 struct TraceSamplerConfig {

include/datadog/trace_sampler_config.h

@@ -1,5 +1,6 @@
 #include "config_manager.h"
 
+#include "json_serializer.h"
 #include "parse_util.h"
 #include "string_util.h"
 #include "trace_sampler.h"
@@ -8,6 +9,20 @@ namespace datadog {
 namespace tracing {
 namespace {
 
+nlohmann::json to_json(const SpanDefaults& defaults) {
+  auto result = nlohmann::json::object({});
+#define TO_JSON(FIELD) \
+  if (!defaults.FIELD.empty()) result[#FIELD] = defaults.FIELD
+  TO_JSON(service);
+  TO_JSON(service_type);
+  TO_JSON(environment);
+  TO_JSON(version);
+  TO_JSON(name);
+  TO_JSON(tags);
+#undef TO_JSON
+  return result;
+}
+
 using Rules = std::vector<TraceSamplerRule>;
 
 Expected<Rules> parse_trace_sampling_rules(const nlohmann::json& json_rules) {
@@ -20,7 +35,7 @@ Expected<Rules> parse_trace_sampling_rules(const nlohmann::json& json_rules) {
   }
 
   for (const auto& json_rule : json_rules) {
-    auto matcher = SpanMatcher::from_json(json_rule);
+    auto matcher = from_json(json_rule);
     if (auto* error = matcher.if_error()) {
       std::string prefix;
       return error->with_prefix(prefix);

src/datadog/config_manager.cpp

@@ -19,7 +19,7 @@ Optional<StringView> lookup(Variable variable) {
   return StringView{value};
 }
 
-nlohmann::json to_json() {
+std::string to_json() {
   auto result = nlohmann::json::object({});
 
   for (const char *name : variable_names) {
@@ -28,7 +28,7 @@ nlohmann::json to_json() {
     }
   }
 
-  return result;
+  return result.dump();
 }
 
 }  // namespace environment