Report trace sampler

Author: anna-git

include/datadog/trace_sampler_config.h

@@ -42,7 +42,9 @@ struct TraceSamplerConfig {
 
 class FinalizedTraceSamplerConfig {
   friend Expected<FinalizedTraceSamplerConfig> finalize_config(
-      const TraceSamplerConfig& config);
+      const TraceSamplerConfig& config,
+      std::unordered_map<ConfigName, std::vector<ConfigMetadata>>*
+          telemetry_configs);
   friend class FinalizedTracerConfig;
 
   FinalizedTraceSamplerConfig() = default;
@@ -58,7 +60,9 @@ class FinalizedTraceSamplerConfig {
 };
 
 Expected<FinalizedTraceSamplerConfig> finalize_config(
-    const TraceSamplerConfig& config);
+    const TraceSamplerConfig& config,
+    std::unordered_map<ConfigName, std::vector<ConfigMetadata>>*
+        telemetry_configs);
 
 }  // namespace tracing
 }  // namespace datadog

src/datadog/trace_sampler_config.cpp

@@ -150,7 +150,9 @@ std::string to_string(const std::vector<TraceSamplerConfig::Rule> &rules) {
 TraceSamplerConfig::Rule::Rule(const SpanMatcher &base) : SpanMatcher(base) {}
 
 Expected<FinalizedTraceSamplerConfig> finalize_config(
-    const TraceSamplerConfig &config) {
+    const TraceSamplerConfig &config,
+    std::unordered_map<ConfigName, std::vector<ConfigMetadata>>
+        *telemetry_configs) {
   Expected<TraceSamplerConfig> env_config = load_trace_sampler_env_config();
   if (auto error = env_config.if_error()) {
     return *error;
@@ -191,27 +193,15 @@ Expected<FinalizedTraceSamplerConfig> finalize_config(
     result.rules.emplace_back(std::move(finalized_rule));
   }
 
-  Optional<double> sample_rate;
-  if (env_config->sample_rate) {
-    sample_rate = env_config->sample_rate;
-    result.metadata[ConfigName::TRACE_SAMPLING_RATE] = ConfigMetadata(
-        ConfigName::TRACE_SAMPLING_RATE, to_string(*sample_rate, 1),
-        ConfigMetadata::Origin::ENVIRONMENT_VARIABLE);
-  } else if (config.sample_rate) {
-    sample_rate = config.sample_rate;
-    result.metadata[ConfigName::TRACE_SAMPLING_RATE] = ConfigMetadata(
-        ConfigName::TRACE_SAMPLING_RATE, to_string(*sample_rate, 1),
-        ConfigMetadata::Origin::CODE);
-  } else {
-    result.metadata[ConfigName::TRACE_SAMPLING_RATE] =
-        ConfigMetadata(ConfigName::TRACE_SAMPLING_RATE, "1.0",
-                       ConfigMetadata::Origin::DEFAULT);
-  }
+  Optional<double> sample_rate = resolve_and_record_config(
+      env_config->sample_rate, config.sample_rate, telemetry_configs,
+      &result.metadata, ConfigName::TRACE_SAMPLING_RATE, 1.0,
+      [](const double &d) { return to_string(d, 1); });
 
   // If `sample_rate` was specified, then it translates to a "catch-all" rule
   // appended to the end of `rules`. First, though, we have to make sure the
   // sample rate is valid.
-  if (sample_rate) {
+  if (sample_rate && (env_config->sample_rate || config.sample_rate)) {
     auto maybe_rate = Rate::from(*sample_rate);
     if (auto *error = maybe_rate.if_error()) {
       return error->with_prefix(
@@ -225,10 +215,8 @@ Expected<FinalizedTraceSamplerConfig> finalize_config(
     result.rules.emplace_back(std::move(finalized_rule));
   }
 
-  std::unordered_map<ConfigName, std::vector<ConfigMetadata>>
-      telemetry_configs_tmp;
   double max_per_second = resolve_and_record_config(
-      env_config->max_per_second, config.max_per_second, &telemetry_configs_tmp,
+      env_config->max_per_second, config.max_per_second, telemetry_configs,
       &result.metadata, ConfigName::TRACE_SAMPLING_LIMIT, 100.0,
       [](const double &d) { return std::to_string(d); });
 

src/datadog/tracer_config.cpp

@@ -421,7 +421,8 @@ Expected<FinalizedTracerConfig> finalize_config(const TracerConfig &user_config,
     return std::move(*error);
   }
 
-  if (auto trace_sampler_config = finalize_config(user_config.trace_sampler)) {
+  if (auto trace_sampler_config =
+          finalize_config(user_config.trace_sampler, &all_sources_configs)) {
     final_config.metadata.merge(trace_sampler_config->metadata);
     final_config.trace_sampler = std::move(*trace_sampler_config);
   } else {