public void Add(T element)
{
/*
* This algorithm tries to update pointer to the next node, as opposed to tail node itself.
* Drawback of this approach is that actual tail is not known, so additional tail look-up
* in the form of nested while loop is required before every insert attempt.
* Alternatevely, CAS operation can be applied to the tail node itself, in which case
* count cannot be calculated along with the insert operation and requires iterating
* when taking a snapshot.
*/
var newNode = new ConcurrentLinkedListNode <T>(element);
var tail = volatileTail;
do
{
while (tail.Next != null)
{
tail = tail.Next;
}
} while (!tail.SetNext(newNode));
volatileTail = newNode;
Interlocked.Increment(ref count);
}
public bool MoveNext()
{
if (index >= count || current == null)
{
return(false);
}
current = current.Next;
++index;
return(current != null);
}
public AppendOnlyConcurrentLinkedListSnapshot(ConcurrentLinkedListNode <T> head, int count)
{
Guard.NotNull("head", head);
this.head = head;
this.count = count;
}
public void Reset()
{
current = head;
index = 0;
}
public AppendOnlyConcurrentLinkedListEnumerator(ConcurrentLinkedListNode <T> head, int count)
{
Guard.NotNull("head", head);
this.current = this.head = head;
this.count = count;
}
public bool SetNext(ConcurrentLinkedListNode <T> newNext)
{
var oldNext = next;
return(Interlocked.CompareExchange(ref next, newNext, oldNext) == oldNext);
}
public AppendOnlyConcurrentLinkedList()
{
volatileTail = head = new ConcurrentLinkedListNode <T>(default(T));
}