Function demonstrateThreadSafeFunctor

examples/threading_patterns.cpp:107–165

}

void demonstrateThreadSafeFunctor()
{
    std::cout << "\n=== Thread-Safe Coordination Demo ===\n";

    std::atomic<int> callCount{0};
    std::mutex functorMutex;
    std::function<void()> safeFunctor;

    // Set the functor to a lambda with manual synchronization
    {
        std::lock_guard<std::mutex> lock (functorMutex);
        safeFunctor = [&callCount]()
        {
            callCount.fetch_add (1);
            std::cout << "Thread-safe function called #" << callCount.load() << "\n";
            std::this_thread::sleep_for (std::chrono::milliseconds (100));
        };
    }

    // Call it from multiple threads
    std::vector<std::thread> threads;

    for (int i = 0; i < 3; ++i)
    {
        threads.emplace_back ([&]()
        {
            std::cout << "Thread " << i << " calling function...\n";
            std::lock_guard<std::mutex> lock (functorMutex);
            if (safeFunctor)
                safeFunctor();
        });
    }

    // Wait for threads to complete
    for (auto& t : threads)
        t.join();

    // Change the functor while demonstrating thread safety
    std::cout << "Changing function implementation safely...\n";
    {
        std::lock_guard<std::mutex> lock (functorMutex);

        safeFunctor = [&callCount]()
        {
            callCount.fetch_add (1);
            std::cout << "NEW thread-safe function implementation called #" << callCount.load() << "\n";
        };
    }

    // Call the new implementation
    {
        std::lock_guard<std::mutex> lock (functorMutex);

        if (safeFunctor)
            safeFunctor();
    }

    std::cout << "Thread-safe function was called " << callCount.load() << " times total\n";