Function main

examples/async.cc:165–291

} // namespace

int main() {
  // A thread that will async perform host function calls.
  std::thread printer_thread([]() {
    int32_t value_to_print = printer_state.get_value_to_print();
    std::cout << "received value to print!" << std::endl;
    std::this_thread::sleep_for(std::chrono::milliseconds(500));
    std::cout << "printing: " << value_to_print << std::endl;
    std::this_thread::sleep_for(std::chrono::milliseconds(500));
    std::cout << "signaling that value is printed" << std::endl;
    printer_state.set_print_success();
  });

  handle<wasmtime_error_t, wasmtime_error_delete> error;

  auto engine = create_engine();
  auto store = create_store(engine.get());
  // This pointer is unowned.
  auto *context = wasmtime_store_context(store.get());
  // Configure the store to periodically yield control
  wasmtime_context_set_fuel(context, 100000);
  wasmtime_context_fuel_async_yield_interval(context, /*interval=*/10000);

  auto compiled_module =
      compile_wat_module_from_file(engine.get(), "examples/async.wat");

  auto linker = create_linker(engine.get());
  static std::string host_module_name = "host";
  static std::string host_func_name = "print";

  // Declare our async host function's signature and definition.
  wasm_valtype_vec_t arg_types;
  wasm_valtype_vec_t result_types;
  wasm_valtype_vec_new_uninitialized(&arg_types, 1);
  arg_types.data[0] = wasm_valtype_new_i32();
  wasm_valtype_vec_new_empty(&result_types);
  handle<wasm_functype_t, wasm_functype_delete> functype{
      wasm_functype_new(&arg_types, &result_types)};

  error.reset(wasmtime_linker_define_async_func(
      linker.get(), host_module_name.data(), host_module_name.size(),
      host_func_name.data(), host_func_name.size(), functype.get(),
      [](void *, wasmtime_caller_t *, const wasmtime_val_t *args, size_t,
         wasmtime_val_t *, size_t, wasm_trap_t **trap_ret,
         wasmtime_async_continuation_t *continuation_ret) {
        std::cout << "invoking async host function" << std::endl;
        printer_state.set_value_to_print(args[0].of.i32);

        continuation_ret->callback = &poll_print_finished_state;
        continuation_ret->env = new async_call_env{trap_ret};
        continuation_ret->finalizer = [](void *env) {
          std::cout << "deleting async_call_env" << std::endl;
          delete static_cast<async_call_env *>(env);
        };
      },
      /*env=*/nullptr, /*finalizer=*/nullptr));
  if (error) {
    exit_with_error("failed to define host function", error.get(), nullptr);
  }