auto whenAllTuple()

in dispenso/detail/future_impl2.h [142:179]

• 31 lines of code
• 5 McCabe index (conditional complexity)

auto whenAllTuple(Invoker& invoker, Futures&&... futures)
    -> Future<std::tuple<std::decay_t<Futures>...>> {
  using TupleType = std::tuple<std::decay_t<Futures>...>;
  using ResultFuture = Future<TupleType>;

  // TODO(bbudge): Can write something faster than make_shared using SmallBufferAllocator.
  auto shared =
      std::make_shared<detail::WhenAllSharedTuple<TupleType>>(std::forward<Futures>(futures)...);

  auto whenComplete = [shared]() -> TupleType {
    forEach(shared->tuple, [&shared](auto& future) {
      if (0 == shared->count.load(std::memory_order_acquire)) {
        return false;
      }
      future.wait();
      return true;
    });
    return std::move(shared->tuple);
  };

  ResultFuture res(std::move(whenComplete), invoker);

  shared->f = std::move(invoker.savedOffFn);
  // Avoid sequencing issue by getting the reference prior to the std::move.
  auto& tuple = shared->tuple;
  forEach(tuple, [shared = std::move(shared)](auto& future) {
    future.then(
        [shared](auto&&) {
          if (shared->count.fetch_sub(1, std::memory_order_release) == 1) {
            shared->f();
          }
        },
        kImmediateInvoker);
    return true;
  });

  return res;
}