atomic/example12.cpp

// atomic_flag as a spinning lock
#include <iostream>       // std::cout
#include <atomic>         // std::atomic_flag
#include <thread>         // std::thread
#include <vector>         // std::vector
#include <sstream>        // std::stringstream

std::atomic_flag lock_stream = ATOMIC_FLAG_INIT;
std::stringstream stream;

void append_number(int x) {
 while (lock_stream.test_and_set()) {}
 stream << "thread #" << x << '\n';
 lock_stream.clear();
}

int main ()
{
 std::vector<std::thread> threads;
 for (int i=1; i<=10; ++i)   threads.push_back(std::thread(append_number,i));
 for (auto& th : threads) th.join();

 std::cout << stream.str();
 return 0;
}