cpp-concurrency/Async.cpp at main · ashutoshdhande/cpp-concurrency · GitHub

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#include <iostream>
#include <thread>
#include <chrono>
#include <future>

using namespace std;

void timeTakingFunc(int duration)
{
    cout << "Started time consuming task thread: " << this_thread::get_id() << endl;
    this_thread::sleep_for(chrono::seconds(duration));
    cout << "Done with time consuming task: " << this_thread::get_id() << endl;
}

void square(int x)
{
    cout << x * x << " : " << this_thread::get_id() << endl;
}

int main()
{

    cout << "Starting program... : " << this_thread::get_id() << endl;

    /*
    - Offload time taking func to another thread
    - this prevents blocking of main thread of execution
    */
    future<void> fut = async(timeTakingFunc, 5);
    /*
    - below func taking same duration as above
    - here by the time this func is finished above func is also finished in another thread
    */
    timeTakingFunc(5);
    for (int i = 1; i < 10; i++)
    {
        square(i);
    }

    fut.get(); // synchronization point

    cout << "Finished program...: " << this_thread::get_id() << endl;

    return 0;
}

/*

OUTPUT BEFORE USING ASYNC
Starting program... : 140645445473216
Started time consuming task thread: 140645445473216
Done with time consuming task: 140645445473216
1
4
9
16
25
36
49
64
81
Finished program...: 140645445473216

=================================================================================================================

Starting program... : 140661222073280
1 : 140661222073280
4 : 140661222073280
9 : 140661222073280
16 : 140661222073280
25 : 140661222073280
36 : 140661222073280
49 : 140661222073280
64 : 140661222073280
81 : 140661222073280
Started time consuming task thread: 140661222057536
Done with time consuming task: 140661222057536
Finished program...: 140661222073280


*/