// The program demonstrates how to cancel a submitted taskflow
// graph and wait until the cancellation completes.

#include <taskflow/taskflow.hpp>

int main() {

 tf::Executor executor;
 tf::Taskflow taskflow("cancel");

 // We create a taskflow graph of 1000 tasks each of 1 second.
 // Ideally, the taskflow completes in 1000/P seconds, where P
 // is the number of workers.
 for(int i=0; i<1000; i++) {
 taskflow.emplace([](){
 std::this_thread::sleep_for(std::chrono::seconds(1));
 });
 }

 // submit the taskflow
 auto beg = std::chrono::steady_clock::now();
 tf::Future fu = executor.run(taskflow);

 // submit a cancel request to cancel all 1000 tasks.
 fu.cancel();

 // wait until the cancellation finishes
 fu.get();
 auto end = std::chrono::steady_clock::now();

 // the duration should be much less than 1000 seconds
 std::cout << "taskflow completes in "
 << std::chrono::duration_cast<std::chrono::milliseconds>(end-beg).count()
 << " milliseconds\n";

 return 0;
}