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

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#include <iostream>
#include <thread>
#include <string>
#include <vector>
#include <mutex>
#include <functional>
#include <condition_variable>
#include <atomic>

using namespace std;

bool pFirst = true;
bool pSecond = true;
bool pThird = true;
condition_variable cv;
mutex mtx;

void printOne(int n)
{
    for (int i = 0; i < n; i++)
    {

        unique_lock<mutex> ulock(mtx);

        cv.wait(ulock, [&]
                { return true == pFirst; });

        cout
            << "first";
        pFirst = false;
        pSecond = true;
        ulock.unlock();
        cv.notify_all();
    }
}

void printTwo(int n)
{
    for (int i = 0; i < n; i++)
    {
        unique_lock<mutex> ulock(mtx);

        cv.wait(ulock, [&]
                { return true == pSecond; });

        cout
            << "second";
        pSecond = false;
        pThird = true;
        ulock.unlock();
        cv.notify_all();
    }
}

void printThree(int n)
{
    for (int i = 0; i < n; i++)
    {
        unique_lock<mutex> ulock(mtx);

        cv.wait(ulock, [&]
                { return true == pThird; });

        cout
            << "third";
        pThird = false;
        pFirst = true;
        ulock.unlock();
        cv.notify_all();
    }
}

int main()
{
    int n = 3;
    thread t1(printOne, n);
    thread t2(printTwo, n);
    thread t3(printThree, n);

    t1.join();
    t2.join();
    t3.join();

    cout << endl;

    return 0;
}