Function BM_EvalString_Trace

eval/tests/modern_benchmark_test.cc:251–283

Benchmark test Traces cel expression with an empty callback: '"a" + "a" + "a" .... + "a"'

// Traces cel expression with an empty callback:
// '"a" + "a" + "a" .... + "a"'
static void BM_EvalString_Trace(benchmark::State& state) {
  RuntimeOptions options = GetOptions();
  options.enable_recursive_tracing = true;

  auto runtime = StandardRuntimeOrDie(options);

  int len = state.range(0);

  Expr root_expr;
  Expr* cur_expr = &root_expr;

  for (int i = 0; i < len; i++) {
    Expr::Call* call = cur_expr->mutable_call_expr();
    call->set_function("_+_");
    call->add_args()->mutable_const_expr()->set_string_value("a");
    cur_expr = call->add_args();
  }

  cur_expr->mutable_const_expr()->set_string_value("a");

  SourceInfo source_info;
  ASSERT_OK_AND_ASSIGN(auto cel_expr, ProtobufRuntimeAdapter::CreateProgram(
                                          *runtime, root_expr));

  for (auto _ : state) {
    google::protobuf::Arena arena;
    Activation activation;
    ASSERT_OK_AND_ASSIGN(cel::Value result,
                         cel_expr->Trace(&arena, activation, EmptyCallback));
    ASSERT_TRUE(InstanceOf<StringValue>(result));
    ASSERT_TRUE(Cast<StringValue>(result).Size() == len + 1);
  }
}

// A number higher than 10k leads to a stack overflow due to the recursive
// nature of the proto to native type conversion.