Async API for wait_and_process

The following code :

auto main() -> int {
auto node = NodeBuilder().create().expect("successful node creation");

auto subscriber = CustomSubscriber::create(node, ServiceName::create("My/Funk/ServiceName").expect(""));

auto waitset = WaitSetBuilder().create().expect("");
// The subscriber is attached as a deadline, meaning that we expect some activity
// latest after the deadline has passed.
auto subscriber_guard = waitset.attach_deadline(subscriber, DEADLINE).expect("");
auto on_event = [&](WaitSetAttachmentId attachment_id) {
// If we have received a new event on the subscriber we handle it.
if (attachment_id.has_event_from(subscriber_guard)) {
subscriber.handle_event();
// If the subscriber did not receive an event until DEADLINE has
// passed, we print out a warning.
} else if (attachment_id.has_missed_deadline(subscriber_guard)) {
std::cout << "Contract violation! The subscriber did not receive a message for " << DEADLINE << std::endl;
}
return CallbackProgression::Continue;
};
waitset.wait_and_process(on_event).expect("");

//some other function
// ...
std::cout << "exit" << std::endl;

return 0;
}

In this code, “waitset.wait_and_process(on_event).expect(""); “ is a blocking function. If there are any other function calls after this, they will be blocked until the wait_and_process method finishes executing. Thus,does we have an async_wait_and_process, which is like to iceoryx1:

listener_ptr
->attachEvent(*subscriber_ptr,
iox::popo::SubscriberEvent::DATA_RECEIVED,
iox::popo::createNotificationCallback(OnReceivedCallback, *handle_ptr))
.or_else([](auto) {
std::cerr << "Unable to attach a subscriber!" << std::endl;
std::exit(EXIT_FAILURE);
});

Start with the waitset.wait_and_process(on_event) entry point shown in the example and compare it with the referenced iceoryx1 listener and attachEvent callback model. Clarify the async operation's execution and completion behavior, including how callers continue with subsequent work. Done means the proposed async API has defined behavior and validation for the non-blocking use case.

Written by the indexing model from the issue text.