How do I handle errors in C++ async libraries?

How do I handle errors in C++ async libraries?

In C++, error handling in async libraries can be done using try-catch blocks or by checking the future's status.

Can you give me an example of using futures for error handling?

Sure! You can use std::async to run a function asynchronously and then check the future for exceptions like this:

#include <future>
#include <iostream>
#include <stdexcept>

int riskyFunction() {
    throw std::runtime_error("An error occurred!");
}

int main() {
    std::future<int> result = std::async(std::launch::async, riskyFunction);
    try {
        result.get(); // This will throw if riskyFunction throws
    } catch (const std::exception& e) {
        std::cout << "Caught an exception: " << e.what() << std::endl;
    }
}

What about using promises for error handling?

You can use promises to handle errors by setting the promise's value or exception. Here's an example:

#include <iostream>
#include <future>
#include <stdexcept>

void asyncFunction(std::promise<int>&& prom) {
    try {
        // Simulate some work
        throw std::runtime_error("Error in async function");
    } catch (...) {
        prom.set_exception(std::current_exception());
    }
}

int main() {
    std::promise<int> prom;
    std::future<int> fut = prom.get_future();
    std::thread(asyncFunction, std::move(prom)).detach();
    try {
        fut.get(); // This will throw if the promise set an exception
    } catch (const std::exception& e) {
        std::cout << "Caught an exception: " << e.what() << std::endl;
    }
}