example3_lock_multiple_mutexes.cpp

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#include <iostream>
#include <thread>
#include <mutex>
#include <vector>

std::mutex mtx1, mtx2, mtx3, mtx4;

void complex_operation(int id) {
    std::vector<std::mutex*> mutexes = {&mtx1, &mtx2, &mtx3, &mtx4};
    
    // Shuffle the order of mutexes to simulate different locking orders
    if (id % 2 == 0) {
        std::swap(mutexes[0], mutexes[3]);
        std::swap(mutexes[1], mutexes[2]);
    }

    std::lock(*mutexes[0], *mutexes[1], *mutexes[2], *mutexes[3]);
    
    std::cout << "Thread " << id << " acquired all locks\n";

    // Unlock in reverse order
    mutexes[3]->unlock();
    mutexes[2]->unlock();
    mutexes[1]->unlock();
    mutexes[0]->unlock();
}

int main() {
    std::vector<std::thread> threads;
    for (int i = 0; i < 4; ++i) {
        threads.emplace_back(complex_operation, i);
    }

    for (auto& t : threads) {
        t.join();
    }

    return 0;
}