#include <iostream>
#include <mutex>
#include <stdexcept> // For runtime_error

using namespace std ;

mutex global_mutex; // A global mutex to protect shared resources

void protected_function()
{
    cout << "Attempting to acquire lock..." << endl;
    // lock_guard acquires the lock in its constructor
    // and automatically releases it in its destructor when it goes out of scope.
    lock_guard<mutex> lock(global_mutex);
    cout << "Lock acquired." << endl;

    // Simulate some work that might throw an exception
    bool should_throw = true; // Set to true to demonstrate exception handling
    if (should_throw) {
        cout << "Throwing an exception..." << endl;
        throw runtime_error("Simulated error in critical section!");
    }

    cout << "Work completed (this line won't be reached if exception is thrown)." << endl;
    // The lock_guard's destructor will be called here if no exception,
    // releasing the mutex.
} // lock_guard goes out of scope here, releasing the mutex (even on exception)

int main()
{
    try
    {
        protected_function();
    }
    catch (const runtime_error& e)
    {
        cerr << "Caught exception in main: " << e.what() << endl;
    }

    // Attempt to acquire the lock again to demonstrate it was released
    cout << "Attempting to acquire lock in main after protected_function..." << endl;
    lock_guard<mutex> lock_in_main(global_mutex);
    cout << "Lock successfully acquired in main, demonstrating previous release." << endl;

    return 0;
}