kimi寫程式碼：tls singleton

#include <iostream>
#include <mutex>
#include <string>
#include <thread>

class ThreadLocalSingleton {
   private:
    ThreadLocalSingleton() {
        std::cout << "created for thread " << std::this_thread::get_id()
                  << std::endl;
    }
    ThreadLocalSingleton(const ThreadLocalSingleton&) = delete;
    ThreadLocalSingleton& operator=(const ThreadLocalSingleton&) = delete;

   public:
    static ThreadLocalSingleton& getInstance() {
        thread_local ThreadLocalSingleton instance;
        return instance;
    }
    void doSomething(std::string msg) {
        std::cout << msg << " from thread " << std::this_thread::get_id()
                  << std::endl;
    }
};

thread_local unsigned int rage = 1;
std::mutex cout_mutex;

void increase_rage(const std::string& thread_name) {
    ++rage;  // modifying outside a lock is okay; this is a thread-local
             // variable
    ThreadLocalSingleton::getInstance().doSomething(thread_name);
    std::lock_guard<std::mutex> lock(cout_mutex);
    std::cout << "Rage counter for " << thread_name << ": " << rage << '\n';
}

int main() {
    std::thread a(increase_rage, "a"), b(increase_rage, "b");

    {
        ThreadLocalSingleton::getInstance().doSomething("main");
        std::lock_guard<std::mutex> lock(cout_mutex);
        std::cout << "Rage counter for main: " << rage << '\n';
    }

    a.join();
    b.join();
}

// https://www.online-cpp.com/

// created for thread 140557953695048
// main from thread 140557953695048
// Rage counter for main: 1

// created for thread 140557951163168
// b from thread 140557951163168
// Rage counter for b: 2

// created for thread 140557951306528
// a from thread 140557951306528
// Rage counter for a: 2