Merge pull request #20329 from soheilhy/call-op-str

Avoid creating and copying strings when Status is OK in FinishOp.

include/grpcpp/impl/codegen/call_op_set.h

@@ -772,21 +772,25 @@ class CallOpClientRecvStatus {
 
   void FinishOp(bool* /*status*/) {
     if (recv_status_ == nullptr || hijacked_) return;
-    grpc::string binary_error_details = metadata_map_->GetBinaryErrorDetails();
+    if (status_code_ == StatusCode::OK) {
+      *recv_status_ = Status();
+      GPR_CODEGEN_DEBUG_ASSERT(GRPC_SLICE_IS_EMPTY(error_message_));
+      GPR_CODEGEN_DEBUG_ASSERT(debug_error_string_ == nullptr);
+    } else {
       *recv_status_ =
           Status(static_cast<StatusCode>(status_code_),
                  GRPC_SLICE_IS_EMPTY(error_message_)
                      ? grpc::string()
                      : grpc::string(GRPC_SLICE_START_PTR(error_message_),
                                     GRPC_SLICE_END_PTR(error_message_)),
-               binary_error_details);
-    client_context_->set_debug_error_string(
-        debug_error_string_ != nullptr ? debug_error_string_ : "");
+                 metadata_map_->GetBinaryErrorDetails());
       g_core_codegen_interface->grpc_slice_unref(error_message_);
       if (debug_error_string_ != nullptr) {
+        client_context_->set_debug_error_string(debug_error_string_);
         g_core_codegen_interface->gpr_free((void*)debug_error_string_);
       }
     }
+  }
 
   void SetInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {