#include <atomic>

#include <bits/c++config.h>

// =============================================================================

// Example: Lock-Free Queue - Uses atomic integer as exclusive index

// =============================================================================

// std::atomic is used as index to non-atomic memory.

// the fetch_add operation ensures any concurrent push() wont fall into the

// same index.

class atomic_queue {

int queue[100];

std::atomic<std::size_t> front;

void push(int x) {

std::size_t exclusive_index = front.fetch_add(1);

queue[exclusive_index] = x;

}

};

// =============================================================================

// Example: Lock Free List - Uses atomic pointer to non-atomic memory (head)

// =============================================================================

class atomic_list {

struct node {

int value;

node *next;

};

std::atomic<node *> head;

void push_front(int x) {

node *new_n = new node;

new_n->value = x;

// if old_head == head, then do head = new_head;

// otherwise, update old_head.

node *old_head = head;

do {

// keep next reference updated.

new_n->next = old_head;

} while (!head.compare_exchange_strong(old_head, new_n));

}

};

// =============================================================================

// Example:

// =============================================================================

int main() { return 0; }