#include <unistd.h>

#include <cstdlib>
#include <iostream>
#include <future>

using namespace std;

//---------------------------------------------------------------
// Async method
//---------------------------------------------------------------
chrono::microseconds asyncMethod(int delay) {

  auto t1 = chrono::high_resolution_clock::now();
  for (int i = 0; i < 4; i++) {
    cout << "  sleep(" << delay << ")" << endl;
    sleep(delay);
  }
  auto t2 = chrono::high_resolution_clock::now();

  return chrono::duration_cast<chrono::microseconds>(t2 - t1);
}

//---------------------------------------------------------------
// The (single) main thread starts executing here.
//---------------------------------------------------------------
int main(int argc, char **argv) {

  // Launch async procedure.  Returns a future.
  auto asyncFuture = async(asyncMethod, 1);

  // now main thread "does something"
  sleep(1);

  // Synchronize w/ async procedure by calling get() on the future
  // that was returned when we launched the async
  cout << asyncFuture.get().count() << endl;

  return EXIT_SUCCESS;
}