C++ std::async wait is taking forever

std::async is a function in C++ that allows you to execute a function asynchronously, meaning it runs in the background while the rest of your program continues executing. When you call std::async, it returns a std::future object that you can use to obtain the result of the asynchronous operation.

In order to wait for the result of the asynchronous operation, you can call the get member function on the std::future object. The get function will block the current thread until the result is available. However, if the asynchronous operation takes a long time to complete, it can cause your program to appear unresponsive.

To address this issue, you can use the std::future::wait_for or std::future::wait_until member functions to wait for the result of the asynchronous operation for a specified amount of time. These functions allow you to set a timeout period, after which they will return and you can check if the operation has completed or not.

Here are the steps involved in using std::async and waiting for the result:

  1. Call std::async and pass the function you want to execute asynchronously as an argument. This will return a std::future object.
  2. Call the wait_for or wait_until member function on the std::future object and specify the desired timeout duration.
  3. The wait_for or wait_until function will return after the specified timeout duration has elapsed or when the asynchronous operation completes, whichever comes first.
  4. Check the return value of the wait_for or wait_until function to determine the status of the asynchronous operation. If it returns std::future_status::ready, it means the operation has completed. If it returns std::future_status::timeout, it means the timeout period elapsed before the operation completed.
  5. If the operation completed, you can obtain the result by calling the get member function on the std::future object.

By using the wait_for or wait_until functions, you can prevent your program from becoming unresponsive while waiting for the result of the asynchronous operation.