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

See also

swaps two jthread objects
(public member function)

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