SpinWait.Reset Method

Definition

Namespace:

System.Threading

Assembly:

System.Threading.dll

Source:

SpinWait.cs

Resets the spin counter.

public:
 void Reset();

public void Reset ();

member this.Reset : unit -> unit

Public Sub Reset ()

Examples

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.)

using System;
using System.Threading;

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();
        }
    }
}

Imports System.Threading

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

Remarks

This makes SpinOnce and NextSpinWillYield behave as though no calls to SpinOnce had been issued on this instance. If a SpinWait instance is reused many times, it may be useful to reset it to avoid yielding too soon.

See also

• SpinWait
• How to: Use SpinWait to Implement a Two-Phase Wait Operation