Mastering C++ Multithreading

Packaged_task

A packaged_task is a wrapper for any callable target (function, bind, lambda, or other function object). It allows for asynchronous execution with the result available in a future object. It is similar to std::function, but automatically transfers its results to a future object.

For example:

#include <iostream> #include <future> #include <chrono>#include <thread> using namespace std;  int countdown (int from, int to) {    for (int i = from; i != to; --i) {          cout << i << '\n';          this_thread::sleep_for(chrono::seconds(1));    }     cout << "Finished countdown.\n";    return from - to; }  int main () {    packaged_task<int(int, int)> task(countdown);   future<int> result = task.get_future();   thread t (std::move(task), 10, 0);  // Other logic. ...