The proper way of terminating the worker thread - c++

Question

Hi I am trying to find out the best peaceful way of terminating a worker thread. I have the following code:
class test{
public:
test() {}
~test() {}
std::atomic<bool> worker_done;
int a;
void pr() {
while (true) {
if (worker_done) {
break;
}
std::this_thread::sleep_for(std::chrono::milliseconds(500));
printf("%d \n", a++);
}
}
std::thread* m_acqThread;
void continuous() {
m_acqThread = new std::thread(&test::pr, this);
}
void stopThread(){
if (m_acqThread) {
if (m_acqThread->joinable())
m_acqThread->join();
delete m_acqThread;
m_acqThread = nullptr;
}
}
};
int main(){
test t;
t.continuous();
std::this_thread::sleep_for(std::chrono::milliseconds(2000));
t.worker_done = true;
t.stopThread();
std::string str;
std::cin.clear();
getline(std::cin, str);
return 0;
Is there a better way of notifying the worker's thread to be terminated other than setting "worker_done" to be true ?
Thanks

Answer 1

What you have is fine: if you have a thread that say starts when your program opens, and as your program closes you need to stop it, using an atomic<bool> is the right way to do this.
It's possible to also use std::atomic_flag like so:
#include <thread>
#include <atomic>
#include <iostream>
std::atomic_flag lock;
int n = 0;
void t()
{
while (lock.test_and_set())
{
++n;
std::this_thread::sleep_for(std::chrono::milliseconds(250));
}
}
int main()
{
lock.test_and_set();
std::thread t(&t);
std::this_thread::sleep_for(std::chrono::seconds(2));
lock.clear();
t.join();
std::cout << n << std::endl;
std::cin.get();
}
You can read about why you might wish to choose atomic_flag over atomic<bool>, but personally I prefer the use of atomic<bool> for things like this, as it's simply more readable:
std::atomic<bool> runThread;
int n = 0;
void t()
{
while (runThread)
{
++n;
std::this_thread::sleep_for(std::chrono::milliseconds(250));
}
}
int main()
{
runThread = true;
std::thread t(&t);
std::this_thread::sleep_for(std::chrono::seconds(2));
runThread = false;
t.join();
std::cout << n << std::endl;
std::cin.get();
}