Added comments and small refactoring.

src/tracer.cc

@@ -438,14 +438,14 @@ TraceManager::Trace::ReportToOpenTelemetry(
     TRITONSERVER_InferenceTrace* trace,
     TRITONSERVER_InferenceTraceActivity activity, uint64_t timestamp_ns)
 {
-  auto current_span_key = GetSpanNameForActivity(activity);
-  if (current_span_key.empty()) {
-    return;
-  }
   uint64_t id;
   LOG_TRITONSERVER_ERROR(
       TRITONSERVER_InferenceTraceId(trace, &id), "getting trace id");
-  current_span_key = current_span_key + std::to_string(id);
+
+  auto current_span_key = GetSpanKeyForActivity(activity, id);
+  if (current_span_key.empty()) {
+    return;
+  }
 
   MaybeStartSpan(current_span_key, trace, activity, timestamp_ns, id);
 
@@ -460,23 +460,23 @@ TraceManager::Trace::ReportToOpenTelemetry(
 }
 
 std::string
-TraceManager::Trace::GetSpanNameForActivity(
-    TRITONSERVER_InferenceTraceActivity activity)
+TraceManager::Trace::GetSpanKeyForActivity(
+    TRITONSERVER_InferenceTraceActivity activity, uint64_t trace_id)
 {
   std::string span_name;
   switch (activity) {
     case TRITONSERVER_TRACE_REQUEST_START:
     case TRITONSERVER_TRACE_QUEUE_START:
     case TRITONSERVER_TRACE_REQUEST_END: {
-      span_name = kRequestSpan;
+      span_name = kRequestSpan + std::to_string(trace_id);
       break;
     }
 
     case TRITONSERVER_TRACE_COMPUTE_START:
     case TRITONSERVER_TRACE_COMPUTE_INPUT_END:
     case TRITONSERVER_TRACE_COMPUTE_OUTPUT_START:
     case TRITONSERVER_TRACE_COMPUTE_END: {
-      span_name = kComputeSpan;
+      span_name = kComputeSpan + std::to_string(trace_id);
       break;
     }
     case TRITONSERVER_TRACE_TENSOR_QUEUE_INPUT:
@@ -509,7 +509,7 @@ void
 TraceManager::Trace::MaybeStartSpan(
     std::string span_key, TRITONSERVER_InferenceTrace* trace,
     TRITONSERVER_InferenceTraceActivity activity, uint64_t timestamp_ns,
-    uint64_t id)
+    uint64_t trace_id)
 {
   if (activity != TRITONSERVER_TRACE_REQUEST_START &&
       activity != TRITONSERVER_TRACE_COMPUTE_START) {
@@ -550,7 +550,7 @@ TraceManager::Trace::MaybeStartSpan(
         "getting model version");
     span->SetAttribute("triton.model_name", model_name);
     span->SetAttribute("triton.model_version", model_version);
-    span->SetAttribute("triton.trace_id", id);
+    span->SetAttribute("triton.trace_id", trace_id);
     span->SetAttribute("triton.trace_parent_id", parent_id);
   }
 

src/tracer.h

@@ -55,7 +55,8 @@ namespace triton { namespace server {
 using TraceConfig = std::vector<std::pair<std::string, std::string>>;
 using TraceConfigMap = std::unordered_map<std::string, TraceConfig>;
 
-// Common OTel span types.
+// Common OTel span keys to store in OTel context
+// with the corresponding trace id.
 constexpr char kRootSpan[] = "root_span";
 constexpr char kRequestSpan[] = "request_span";
 constexpr char kComputeSpan[] = "compute_span";
@@ -171,18 +172,28 @@ class TraceManager {
     void CaptureTimestamp(const std::string& name, uint64_t timestamp_ns);
 
 #if !defined(_WIN32) && defined(TRITON_ENABLE_TRACING)
-    // Initializes Opentelemetry exporter, processor, provider and context
+    /// Initializes Opentelemetry exporter, processor, provider and context.
+    ///
+    /// \param config_map A config map, which stores all parameters, specified
+    /// by user.
     void InitTracer(const TraceConfigMap& config_map);
 
-    // Reports TRITONSERVER_InferenceTraceActivity as event to
-    // the currently active span. If activity is an instance of
-    // `TRITONSERVER_TRACE_REQUEST_START` or
-    // `TRITONSERVER_TRACE_COMPUTE_START`,
-    // it starts a new request or compute span. For the request span it
-    // adds some triton related attributes, and adds this span to
-    // `otel_context_`. Alternatively, if activity is
-    // `TRITONSERVER_TRACE_REQUEST_END` or `TRITONSERVER_TRACE_COMPUTE_END`,
-    // it ends the corresponding span.
+    /// Reports TRITONSERVER_InferenceTraceActivity as event to
+    /// the currently active span. If activity is an instance of
+    /// `TRITONSERVER_TRACE_REQUEST_START` or
+    /// `TRITONSERVER_TRACE_COMPUTE_START`,
+    /// it starts a new request or compute span. For the request span it
+    /// adds some triton related attributes, and adds this span to
+    /// `otel_context_`. Alternatively, if activity is
+    /// `TRITONSERVER_TRACE_REQUEST_END` or `TRITONSERVER_TRACE_COMPUTE_END`,
+    /// it ends the corresponding span.
+    ///
+    /// \param trace TRITONSERVER_InferenceTrace instance.
+    /// \param activity  Trace activity.
+    /// \param timestamp_ns Steady timestamp, which is used to calculate
+    /// OpenTelemetry SystemTimestamp to display span on a timeline, and
+    /// OpenTelemetry SteadyTimestamp to calculate the duration on the span
+    /// with better precision.
     void ReportToOpenTelemetry(
         TRITONSERVER_InferenceTrace* trace,
         TRITONSERVER_InferenceTraceActivity activity, uint64_t timestamp_ns);
@@ -213,34 +224,74 @@ class TraceManager {
     // OTel context to store spans, created in the current trace
     opentelemetry::context::Context otel_context_;
 
-    // Starts a span with the provided timestamp
+    /// Starts a span with the provided timestamp.
+    ///
+    /// \param display_name Span's name, which will be shown in the trace.
+    /// \param raw_timestamp_ns Steady timestamp, which is used to calculate
+    /// OpenTelemetry SystemTimestamp to display span on a timeline, and
+    /// OpenTelemetry SteadyTimestamp to calculate the duration on the span
+    /// with better precision.
+    /// \param is_root_span If true, a root span will be started,
+    /// i.e. with no parent span specified. If false, a new child span will
+    /// be started.
+    /// \param parent_span_key A span key, to find a parent span in the
+    /// OpenTelemetry context.
+    /// \return A shared pointer to a newly created OpenTelemetry span.
     opentelemetry::nostd::shared_ptr<otel_trace_api::Span> StartSpan(
         std::string display_name, const uint64_t& raw_timestamp_ns,
         bool is_root_span, std::string parent_span_key = "");
 
-    // Ends the provided span
+    /// Ends the provided span.
+    ///
+    /// \param span_key Span's key to retrieve the corresponding span from the
+    /// OpenTelemetry context.
     void EndSpan(std::string span_key);
 
-    // Ends the provided span at specified steady timestamp
+    /// Ends the provided span at specified steady timestamp.
+    ///
+    /// \param span_key Span's key to retrieve the corresponding span from the
+    /// OpenTelemetry context.
+    /// \param raw_timestamp_ns Steady timestamp to use as
+    /// `EndSpanOptions::end_steady_time`.
     void EndSpan(std::string span_key, const uint64_t& raw_timestamp_ns);
 
-    // Returns the span key, for which the activity belongs
-    std::string GetSpanNameForActivity(
-        TRITONSERVER_InferenceTraceActivity activity);
-
-    // Adds event to a span
+    /// Returns the span key, for which the activity belongs.
+    ///
+    /// \param activity reported activity.
+    /// \param trace_id Trace id.
+    /// \return A key to identify span, stored in the OpenTelemetry context.
+    std::string GetSpanKeyForActivity(
+        TRITONSERVER_InferenceTraceActivity activity, uint64_t trace_id);
+
+    /// Adds event to the span.
+    ///
+    /// \param span_key Span's key to retrieve the corresponding span from the
+    /// OpenTelemetry context.
+    /// \param event An event to add to the span.
+    /// \param timestamp_ns Timestamp of the provided event.
     void AddEvent(
         std::string span_key, std::string event, uint64_t timestamp_ns);
 
-    // If activity is TRITONSERVER_TRACE_REQUEST_START, or
-    // TRITONSERVER_TRACE_COMPUTE_START, starts a new span and adds it to
-    // `otel_context_`. If the newly started span is a request span, then
-    // it will set `model_name`, `model_version`, `trace_id`, `trace_parent_id`,
-    // as span's attributes.
+    /// If activity is TRITONSERVER_TRACE_REQUEST_START, or
+    /// TRITONSERVER_TRACE_COMPUTE_START, starts a new span and adds it to
+    /// `otel_context_`. If the newly started span is a request span, then
+    /// it will set `model_name`, `model_version`, `trace_id`,
+    /// `trace_parent_id`, as span's attributes.
+    ///
+    /// \param span_key Span's key to retrieve the corresponding span from the
+    /// OpenTelemetry context.
+    /// \param trace TRITONSERVER_InferenceTrace, used to request model's name,
+    /// version, trace parent_id from the backend.
+    /// \param activity Trace activity.
+    /// \param timestamp_ns Steady timestamp, which is used to calculate
+    /// OpenTelemetry SystemTimestamp to display span on a timeline, and
+    /// OpenTelemetry SteadyTimestamp to calculate the duration on the span
+    /// with better precision.
+    /// \param trace_id Trace id.
     void MaybeStartSpan(
         std::string span_key, TRITONSERVER_InferenceTrace* trace,
         TRITONSERVER_InferenceTraceActivity activity, uint64_t timestamp_ns,
-        uint64_t id);
+        uint64_t trace_id);
 #endif
   };