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