Function TestSafeCallIntoR

r/src/safe-call-into-r-impl.cpp:51–100

[[arrow::export]]

// [[arrow::export]]
std::string TestSafeCallIntoR(cpp11::function r_fun_that_returns_a_string,
                              std::string opt) {
  if (opt == "async_with_executor") {
    std::thread thread;

    auto result = RunWithCapturedR<std::string>([&thread, r_fun_that_returns_a_string]() {
      auto fut = arrow::Future<std::string>::Make();
      thread = std::thread([&fut, r_fun_that_returns_a_string]() {
        auto result = SafeCallIntoR<std::string>(
            [&] { return cpp11::as_cpp<std::string>(r_fun_that_returns_a_string()); });

        fut.MarkFinished(result);
      });

      return fut;
    });

    if (thread.joinable()) {
      thread.join();
    }

    return arrow::ValueOrStop(result);
  } else if (opt == "async_without_executor") {
    auto fut = arrow::Future<std::string>::Make();
    std::thread thread([&fut, r_fun_that_returns_a_string]() {
      auto result = SafeCallIntoR<std::string>(
          [&] { return cpp11::as_cpp<std::string>(r_fun_that_returns_a_string()); });

      if (result.ok()) {
        fut.MarkFinished(result.ValueUnsafe());
      } else {
        fut.MarkFinished(result.status());
      }
    });

    thread.join();

    // We should be able to get this far, but fut will contain an error
    // because it tried to evaluate R code from another thread
    return arrow::ValueOrStop(fut.result());

  } else if (opt == "on_main_thread") {
    auto result = SafeCallIntoR<std::string>(
        [&]() { return cpp11::as_cpp<std::string>(r_fun_that_returns_a_string()); });
    arrow::StopIfNotOk(result.status());
    return result.ValueUnsafe();
  } else {
    cpp11::stop("Unknown `opt`");
  }
}