if(argc != 2) {

std::cerr << "usage: ./for_loop num_iterations" << std::endl;

std::exit(EXIT_FAILURE);

}

const size_t N = std::atoi(argv[1]);

// expressing loop using Taskflow's control taskflow graph programming model

tf::Executor executor;

tf::Taskflow taskflow;

auto X = taskflow.emplace([](){});

auto Y = taskflow.emplace([&, i=size_t(0)]() mutable {

loop_body();

return (i++ < N) ? 0 : 1;

});

auto Z = taskflow.emplace([](){});

X.precede(Y);

Y.precede(Y, Z);

auto tbeg = std::chrono::steady_clock::now();

executor.run(taskflow).wait();

auto tend = std::chrono::steady_clock::now();

std::cout << "in-graph control flow time : " << std::chrono::duration_cast<std::chrono::microseconds>(tend-tbeg).count()

<< " us\n";

// expressing the loop without using cointrol taskflow graph

tf::Taskflow taskflow_x, taskflow_y, taskflow_z;

taskflow_x.emplace([](){});

taskflow_y.emplace(loop_body);

taskflow_z.emplace([](){});

tbeg = std::chrono::steady_clock::now();

executor.run(taskflow_x).wait();

for(size_t i=0; i<N; ++i) {

executor.run(taskflow_y).wait();

}

executor.run(taskflow_z).wait();

tend = std::chrono::steady_clock::now();

std::cout << "out-of-graph control flow time: " << std::chrono::duration_cast<std::chrono::microseconds>(tend-tbeg).count()

<< " us\n";

return 0;