(C++ : Concurrency) 10. latch & barrier

#include <iostream>
#include <mutex>
#include <latch>
#include <thread>

void foo(std::string name)
{
    std::cout << "start work : " << name << std::endl;
    std::cout << "finish work : " << name << std::endl;

    // 세 스레드에서 집에가는 동작은 같이 하고 싶다면?
    std::cout << "go home : " << name << std::endl;
}

int main()
{
    std::jthread t1(foo, "kim"), t2(foo, "lee"), t3(foo, "park");
}

#include <iostream>
#include <mutex>
#include <latch>
#include <thread>

std::latch complete{3};
std::latch gohome{1};

void foo(std::string name)
{
    std::cout << "start work : " << name << std::endl;
    std::cout << "finish work : " << name << std::endl;
    complete.count_down();
    gohome.wait();
    std::cout << "go home : " << name << std::endl;
}

int main()
{
    std::jthread t1(foo, "kim"), t2(foo, "lee"), t3(foo, "park");

    complete.wait();    // 카운트가 0일때까지 대기
    gohome.count_down();
}

#include <iostream>
#include <mutex>
#include <latch>
#include <thread>

std::latch sync_point{3};

void foo(std::string name)
{
    std::cout << "start work : " << name << std::endl;
    std::cout << "finish work : " << name << std::endl;

    sync_point.arrive_and_wait();   // 카운트를 1줄이고, 카운트가 0일때까지 대기한다

    std::cout << "go home : " << name << std::endl;

    sync_point.arrive_and_wait();   // Error - latch는 1회만 쓸 수 있다 여러번 쓰려면 barrier를 쓰자
}

int main()
{
    std::jthread t1(foo, "kim"), t2(foo, "lee"), t3(foo, "park");
}

#include <iostream>
#include <mutex>
#include <barrier>
#include <thread>

void oncomplete()
{
    std::cout << "oncomplete" << name << std::endl;
}

std::barrier sync_point{3, oncomplete}; // 콜백함수도 선언가능

void foo(std::string name)
{
    std::cout << "start work : " << name << std::endl;
    std::cout << "finish work : " << name << std::endl;

    sync_point.arrive_and_wait();

    std::cout << "go home : " << name << std::endl;

    sync_point.arrive_and_wait();   // 2회 써도 무방
}

int main()
{
    std::jthread t1(foo, "kim"), t2(foo, "lee"), t3(foo, "park");
}