Lock Free Stack Implementation in C#
This method compares destination to currentValue, and if they're equal sets destination to newValue and returns currentValue unchanged.
If they aren't equal it just returns the value of destination.
This is done in an atomic fashion i.e. no other thread can interrupt it. In carrys out this in atomic fashion becasue its executed at hardware level with a single nstruction CMPXCH instruction.
public class LockFreeStack<T> {
private volatile StackNode<T> m_head;
private static bool CAS(ref Node<T> destination, Node<T> currentValue, Node<T> newValue)
{
return
currentValue== Interlocked.CompareExchange<Node<T>>(ref destination, newValue, currentValue);
}
public void Push(T item) {
StackNode<T> node = new StackNode<T>(item);
StackNode<T> head;
do {
head = m_head;
node.m_next = head;
} while (m_head != head || CAS(ref m_head, node, head) != head);
…
If they aren't equal it just returns the value of destination.
This is done in an atomic fashion i.e. no other thread can interrupt it. In carrys out this in atomic fashion becasue its executed at hardware level with a single nstruction CMPXCH instruction.
public class LockFreeStack<T> {
private volatile StackNode<T> m_head;
private static bool CAS(ref Node<T> destination, Node<T> currentValue, Node<T> newValue)
{
return
currentValue== Interlocked.CompareExchange<Node<T>>(ref destination, newValue, currentValue);
}
public void Push(T item) {
StackNode<T> node = new StackNode<T>(item);
StackNode<T> head;
do {
head = m_head;
node.m_next = head;
} while (m_head != head || CAS(ref m_head, node, head) != head);
…
