Reviewer comments

src/core/lib/channel/call_tracer.h

@@ -51,6 +51,8 @@ class CallTracer {
     virtual void RecordSendTrailingMetadata(
         grpc_metadata_batch* send_trailing_metadata) = 0;
     virtual void RecordSendMessage(const ByteStream& send_message) = 0;
+    // The `RecordReceivedxx()` methods should only be invoked when the
+    // metadata/message was successfully received, i.e., without any error.
     // TODO(yashkt): We are using gpr_atm here instead of absl::string_view
     // since that's what the transport API uses, and performing an atomic load
     // is unnecessary if the census tracer does not need it at present. Fix this
@@ -62,9 +64,6 @@ class CallTracer {
     virtual void RecordReceivedTrailingMetadata(
         grpc_metadata_batch* recv_trailing_metadata) = 0;
     virtual void RecordCancel(grpc_error_handle cancel_error) = 0;
-    // Records annotations if supported by the attached tracer library, no-op
-    // otherwise.
-    virtual void RecordAnnotation(absl::string_view annotation) = 0;
     // Should be the last API call to the object. Once invoked, the tracer
     // library is free to destroy the object.
     virtual void RecordEnd(const grpc_call_final_info& final_info) = 0;
@@ -74,15 +73,12 @@ class CallTracer {
 
   // Records a new attempt for the associated call. \a transparent denotes
   // whether the attempt is being made as a transparent retry or as a
-  // non-transparent retry/heding attempt. (There will be atleast one attempt
+  // non-transparent retry/heding attempt. (There will be at least one attempt
   // even if the call is not being retried.) The `CallTracer` object retains
   // ownership to the newly created `CallAttemptTracer` object. RecordEnd()
   // serves as an indication that the call stack is done with all API calls, and
   // the tracer library is free to destroy it after that.
   virtual CallAttemptTracer* StartNewAttempt(bool is_transparent_retry) = 0;
-  // Records annotations if supported by the attached tracer library, no-op
-  // otherwise.
-  virtual void RecordAnnotation(absl::string_view annotation) = 0;
 };
 
 }  // namespace grpc_core

src/cpp/ext/filters/census/open_census_call_tracer.h

@@ -46,7 +46,6 @@ class OpenCensusCallTracer : public grpc_core::CallTracer {
     void RecordReceivedTrailingMetadata(
         grpc_metadata_batch* /* recv_trailing_metadata */) override {}
     void RecordCancel(grpc_error_handle /* cancel_error */) override {}
-    void RecordAnnotation(absl::string_view /* annotation */) override {}
     void RecordEnd(const grpc_call_final_info& /* final_info */) override {}
 
     CensusContext* context() { return &context_; }
@@ -59,7 +58,6 @@ class OpenCensusCallTracer : public grpc_core::CallTracer {
       bool /* is_transparent_retry */) override {
     return nullptr;
   }
-  void RecordAnnotation(absl::string_view /* annotation */) override {}
 
   CensusContext* context() { return &context_; }