swap(std::jthread)

friend void swap( jthread& lhs, jthread& rhs ) noexcept;

(since C++20)

Overloads the std::swap algorithm for std::jthread. Exchanges the state of lhs with that of rhs. Effectively calls lhs.swap(rhs). This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::jthread is an associated class of the arguments.

Parameters

lhs, rhs

jthreads whose states to swap

Return value

(none)

Example

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

void foo()
{
    std::this_thread::sleep_for(std::chrono::seconds(1));
}

void bar()
{
    std::this_thread::sleep_for(std::chrono::seconds(1));
}

int main()
{
    using std::swap;

    std::jthread t1(foo);
    std::jthread t2(bar);

    std::cout << "thread 1 id: " << t1.get_id() << '\n'
              << "thread 2 id: " << t2.get_id() << '\n';

    swap(t1, t2);

    std::cout << "after std::swap(t1, t2):" << '\n'
              << "thread 1 id: " << t1.get_id() << '\n'
              << "thread 2 id: " << t2.get_id() << '\n';

    t1.swap(t2);

    std::cout << "after t1.swap(t2):" << '\n'
              << "thread 1 id: " << t1.get_id() << '\n'
              << "thread 2 id: " << t2.get_id() << '\n';

    
}

Possible output:

thread 1 id: 1892
thread 2 id: 2584
after std::swap(t1, t2):
thread 1 id: 2584
thread 2 id: 1892
after t1.swap(t2):
thread 1 id: 1892
thread 2 id: 2584

swap(std::jthread)

Parameters

Return value

Example

See also