/// <summary>
/// Removes and returns the object at the beginning of the queue.
/// </summary>
/// <param name="item">
/// when the method returns, contains the object removed from the beginning of the queue,
/// if the queue is not empty; otherwise it is the default value for the element type
/// </param>
/// <returns>
/// true if an object from removed from the beginning of the queue;
/// false if the queue is empty
/// </returns>
public bool TryDequeue(out T item)
{
item = default(T);
bool flag = false;
while (!flag)
{
SingleLinkNode <T> head = _head;
SingleLinkNode <T> tail = _tail;
SingleLinkNode <T> next = head.Next;
if (head == _head)
{
if (head == tail)
{
if (next == null)
{
return(false);
}
Interlocked.CompareExchange(ref _tail, next, tail);
}
else
{
item = next.Item;
flag = Interlocked.CompareExchange(ref _head, next, head) == head;
}
}
}
Interlocked.Decrement(ref _count);
return(true);
}
/// <summary>
/// Adds an object to the end of the queue.
/// </summary>
/// <param name="item">the object to add to the queue</param>
public void Enqueue(T item)
{
SingleLinkNode <T> oldTail = null;
SingleLinkNode <T> oldTailNext;
var newNode = new SingleLinkNode <T> {
Item = item
};
bool newNodeWasAdded = false;
while (!newNodeWasAdded)
{
oldTail = _tail;
oldTailNext = oldTail.Next;
if (_tail == oldTail)
{
if (oldTailNext == null)
{
newNodeWasAdded =
Interlocked.CompareExchange <SingleLinkNode <T> >(ref _tail.Next, newNode, null) == null;
}
else
{
Interlocked.CompareExchange <SingleLinkNode <T> >(ref _tail, oldTailNext, oldTail);
}
}
}
Interlocked.CompareExchange <SingleLinkNode <T> >(ref _tail, newNode, oldTail);
Interlocked.Increment(ref _count);
}
/// <summary>Adds an object to the end of the queue.</summary>
/// <param name="item">the object to add to the queue</param>
public void Enqueue(T item)
{
SingleLinkNode <T> comparand = null;
SingleLinkNode <T> singleLinkNode = new SingleLinkNode <T>
{
Item = item
};
bool flag = false;
while (!flag)
{
comparand = _tail;
SingleLinkNode <T> next = comparand.Next;
if (_tail == comparand)
{
if (next == null)
{
flag = Interlocked.CompareExchange(ref _tail.Next, singleLinkNode,
null) == null;
}
else
{
Interlocked.CompareExchange(ref _tail, next, comparand);
}
}
}
Interlocked.CompareExchange(ref _tail, singleLinkNode, comparand);
Interlocked.Increment(ref _count);
}
/// <summary>Inserts an object at the top of the stack.</summary>
/// <param name="item">the object to push onto the stack</param>
public void Push(T item)
{
SingleLinkNode<T> singleLinkNode = new SingleLinkNode<T>();
singleLinkNode.Item = item;
do
{
singleLinkNode.Next = _head.Next;
} while(Interlocked.CompareExchange(ref _head.Next, singleLinkNode,
singleLinkNode.Next) != singleLinkNode.Next);
}
/// <summary>
/// Inserts an object at the top of the stack.
/// </summary>
/// <param name="item">the object to push onto the stack</param>
public void Push(T item)
{
SingleLinkNode <T> newNode = new SingleLinkNode <T>();
newNode.Item = item;
do
{
newNode.Next = _head.Next;
} while (Interlocked.CompareExchange <SingleLinkNode <T> >(ref _head.Next, newNode, newNode.Next) != newNode.Next);
}
/// <summary>
/// Returns an enumerator that iterates through the queue.
/// </summary>
/// <returns>an enumerator for the queue</returns>
public IEnumerator <T> GetEnumerator()
{
SingleLinkNode <T> currentNode = _head;
while (currentNode.Item != null)
{
yield return(currentNode.Item);
if ((currentNode = currentNode.Next) == null)
{
break;
}
}
}
/// <summary>Clears the queue.</summary>
/// <remarks>This method is not thread-safe.</remarks>
public void Clear()
{
SingleLinkNode <T> singleLinkNode1 = _head;
while (singleLinkNode1 != null)
{
SingleLinkNode <T> singleLinkNode2 = singleLinkNode1;
singleLinkNode1 = singleLinkNode1.Next;
singleLinkNode2.Item = default(T);
singleLinkNode2.Next = null;
}
_head = new SingleLinkNode <T>();
_tail = _head;
_count = 0;
}
/// <summary>Clears the queue.</summary>
/// <remarks>This method is not thread-safe.</remarks>
public void Clear()
{
SingleLinkNode <T> singleLinkNode1 = this._head;
while (singleLinkNode1 != null)
{
SingleLinkNode <T> singleLinkNode2 = singleLinkNode1;
singleLinkNode1 = singleLinkNode1.Next;
singleLinkNode2.Item = default(T);
singleLinkNode2.Next = (SingleLinkNode <T>)null;
}
this._head = new SingleLinkNode <T>();
this._tail = this._head;
this._count = 0;
}
/// <summary>
/// Clears the queue.
/// </summary>
/// <remarks>This method is not thread-safe.</remarks>
public void Clear()
{
SingleLinkNode <T> tempNode;
SingleLinkNode <T> currentNode = _head;
while (currentNode != null)
{
tempNode = currentNode;
currentNode = currentNode.Next;
tempNode.Item = default(T);
tempNode.Next = null;
}
_head = new SingleLinkNode <T>();
_tail = _head;
_count = 0;
}
/// <summary>
/// Returns an enumerator that iterates through the queue.
/// </summary>
/// <returns>an enumerator for the queue</returns>
public IEnumerator <T> GetEnumerator()
{
SingleLinkNode <T> currentNode = _head;
do
{
if (currentNode.Item == null)
{
yield break;
}
else
{
yield return(currentNode.Item);
}
}while ((currentNode = currentNode.Next) != null);
yield break;
}
/// <summary>
/// Removes and returns the object at the beginning of the queue.
/// </summary>
/// <param name="item">
/// when the method returns, contains the object removed from the beginning of the queue,
/// if the queue is not empty; otherwise it is the default value for the element type
/// </param>
/// <returns>
/// true if an object from removed from the beginning of the queue;
/// false if the queue is empty
/// </returns>
public bool TryDequeue(out T item)
{
item = default(T);
SingleLinkNode <T> oldHead = null;
bool haveAdvancedHead = false;
while (!haveAdvancedHead)
{
oldHead = _head;
SingleLinkNode <T> oldTail = _tail;
SingleLinkNode <T> oldHeadNext = oldHead.Next;
if (oldHead == _head)
{
if (oldHead == oldTail)
{
if (oldHeadNext == null)
{
return(false);
}
Interlocked.CompareExchange <SingleLinkNode <T> >(ref _tail, oldHeadNext, oldTail);
}
else
{
item = oldHeadNext.Item;
haveAdvancedHead =
Interlocked.CompareExchange <SingleLinkNode <T> >(ref _head, oldHeadNext, oldHead) == oldHead;
}
}
}
Interlocked.Decrement(ref _count);
return(true);
}
/// <summary>Default constructors.</summary>
public LockFreeStack()
{
this._head = new SingleLinkNode <T>();
}
/// <summary>Default constructor.</summary>
public LockfreeQueue()
{
_head = new SingleLinkNode <T>();
_tail = _head;
}
/// <summary>Default constructor.</summary>
public LockfreeQueue()
{
this._head = new SingleLinkNode <T>();
this._tail = this._head;
}
