SpinWait::Reset Method ()

The following is an example of using SpinWait in a simple lock-free stack implementation. (This is just an example. If an efficient, thread-safe stack is needed, consider using ConcurrentStack.)

// C#

public class LockFreeStack<T>

{

private volatile Node m_head;

private class Node { public Node Next; public T Value; }

public void Push(T item)

{

var spin = new SpinWait();

Node node = new Node { Value = item }, head;

while (true)

{

head = m_head;

node.Next = head;

if (Interlocked.CompareExchange(ref m_head, node, head) == head) break;

spin.SpinOnce();

}

}

public bool TryPop(out T result)

{

result = default(T);

var spin = new SpinWait();

Node head;

while (true)

{

head = m_head;

if (head == null) return false;

if (Interlocked.CompareExchange(ref m_head, head.Next, head) == head)

{

result = head.Value;

return true;

}

spin.SpinOnce();

}

}

}

' Visual Basic

Public Class LockFreeStack(Of T)

Private m_head As Node

Private Class Node

Public [Next] As Node

Public Value As T

End Class

Public Sub Push(ByVal item As T)

Dim spin As New SpinWait()

Dim head As Node, node As New Node With {.Value = item}

While True

Thread.MemoryBarrier()

head = m_head

node.Next = head

If Interlocked.CompareExchange(m_head, node, head) Is head Then Exit While

spin.SpinOnce()

End While

End Sub

Public Function TryPop(ByRef result As T) As Boolean

result = CType(Nothing, T)

Dim spin As New SpinWait()

Dim head As Node

While True

Thread.MemoryBarrier()

head = m_head

If head Is Nothing Then Return False

If Interlocked.CompareExchange(m_head, head.Next, head) Is head Then

result = head.Value

Return True

End If

spin.SpinOnce()

End While

End Function

End Class