Interlocked.CompareExchange Methode

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

public:
 static UIntPtr CompareExchange(UIntPtr % location1, UIntPtr value, UIntPtr comparand);

[System.CLSCompliant(false)]
public static UIntPtr CompareExchange (ref UIntPtr location1, UIntPtr value, UIntPtr comparand);

[<System.CLSCompliant(false)>]
static member CompareExchange : unativeint * unativeint * unativeint -> unativeint

Public Shared Function CompareExchange (ByRef location1 As UIntPtr, value As UIntPtr, comparand As UIntPtr) As UIntPtr

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Attribute

CLSCompliantAttribute

Ausnahmen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

public:
 static System::UInt64 CompareExchange(System::UInt64 % location1, System::UInt64 value, System::UInt64 comparand);

[System.CLSCompliant(false)]
public static ulong CompareExchange (ref ulong location1, ulong value, ulong comparand);

[<System.CLSCompliant(false)>]
static member CompareExchange : uint64 * uint64 * uint64 -> uint64

Public Shared Function CompareExchange (ByRef location1 As ULong, value As ULong, comparand As ULong) As ULong

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Attribute

CLSCompliantAttribute

Ausnahmen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

public:
 static System::UInt32 CompareExchange(System::UInt32 % location1, System::UInt32 value, System::UInt32 comparand);

[System.CLSCompliant(false)]
public static uint CompareExchange (ref uint location1, uint value, uint comparand);

[<System.CLSCompliant(false)>]
static member CompareExchange : uint32 * uint32 * uint32 -> uint32

Public Shared Function CompareExchange (ByRef location1 As UInteger, value As UInteger, comparand As UInteger) As UInteger

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Attribute

CLSCompliantAttribute

Ausnahmen

public:
 static System::UInt16 CompareExchange(System::UInt16 % location1, System::UInt16 value, System::UInt16 comparand);

[System.CLSCompliant(false)]
public static ushort CompareExchange (ref ushort location1, ushort value, ushort comparand);

[<System.CLSCompliant(false)>]
static member CompareExchange : uint16 * uint16 * uint16 -> uint16

Public Shared Function CompareExchange (ByRef location1 As UShort, value As UShort, comparand As UShort) As UShort

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Attribute

CLSCompliantAttribute

Ausnahmen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

public:
 static float CompareExchange(float % location1, float value, float comparand);

public static float CompareExchange (ref float location1, float value, float comparand);

static member CompareExchange : single * single * single -> single

Public Shared Function CompareExchange (ByRef location1 As Single, value As Single, comparand As Single) As Single

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Beispiele

Im folgenden Codebeispiel wird eine threadsichere Methode veranschaulicht, die eine laufende Summe von Single Werten ansammelt. Zwei Threads fügen eine Reihe von Single Werten mithilfe der threadsicheren Methode und gewöhnlichen Hinzufügung hinzu, und wenn die Threads die Summen abschließen, werden verglichen. Auf einem Dualprozessorcomputer gibt es einen erheblichen Unterschied in den Summen.

In der threadsicheren Methode wird der Anfangswert der ausgeführten Summe gespeichert, und dann wird die CompareExchange Methode verwendet, um die neu berechnete Summe mit der alten Summe auszutauschen. Wenn der Rückgabewert nicht dem gespeicherten Wert der laufenden Summe entspricht, hat ein anderer Thread die Summe in der Zwischenzeit aktualisiert. In diesem Fall muss der Versuch, die laufende Summe zu aktualisieren, wiederholt werden.

// This example demonstrates a thread-safe method that adds to a
// running total.  
using System;
using System.Threading;

public class ThreadSafe
{
    // Field totalValue contains a running total that can be updated
    // by multiple threads. It must be protected from unsynchronized 
    // access.
    private float totalValue = 0.0F;

    // The Total property returns the running total.
    public float Total { get { return totalValue; }}

    // AddToTotal safely adds a value to the running total.
    public float AddToTotal(float addend)
    {
        float initialValue, computedValue;
        do
        {
            // Save the current running total in a local variable.
            initialValue = totalValue;

            // Add the new value to the running total.
            computedValue = initialValue + addend;

            // CompareExchange compares totalValue to initialValue. If
            // they are not equal, then another thread has updated the
            // running total since this loop started. CompareExchange
            // does not update totalValue. CompareExchange returns the
            // contents of totalValue, which do not equal initialValue,
            // so the loop executes again.
        }
        while (initialValue != Interlocked.CompareExchange(ref totalValue, 
            computedValue, initialValue));
        // If no other thread updated the running total, then 
        // totalValue and initialValue are equal when CompareExchange
        // compares them, and computedValue is stored in totalValue.
        // CompareExchange returns the value that was in totalValue
        // before the update, which is equal to initialValue, so the 
        // loop ends.

        // The function returns computedValue, not totalValue, because
        // totalValue could be changed by another thread between
        // the time the loop ends and the function returns.
        return computedValue;
    }
}

public class Test
{
    // Create an instance of the ThreadSafe class to test.
    private static ThreadSafe ts = new ThreadSafe();
    private static float control;

    private static Random r = new Random();
    private static ManualResetEvent mre = new ManualResetEvent(false);

    public static void Main()
    {
        // Create two threads, name them, and start them. The
        // thread will block on mre.
        Thread t1 = new Thread(TestThread);
        t1.Name = "Thread 1";
        t1.Start();
        Thread t2 = new Thread(TestThread);
        t2.Name = "Thread 2";
        t2.Start();

        // Now let the threads begin adding random numbers to 
        // the total.
        mre.Set();
        
        // Wait until all the threads are done.
        t1.Join();
        t2.Join();

        Console.WriteLine("Thread safe: {0}  Ordinary float: {1}", 
            ts.Total, control);
    }

    private static void TestThread()
    {
        // Wait until the signal.
        mre.WaitOne();

        for(int i = 1; i <= 1000000; i++)
        {
            // Add to the running total in the ThreadSafe instance, and
            // to an ordinary float.
            //
            float testValue = (float) r.NextDouble();
            control += testValue;
            ts.AddToTotal(testValue);
        }
    }
}

/* On a dual-processor computer, this code example produces output 
   similar to the following:

Thread safe: 17039.57  Ordinary float: 15706.44
 */

' This example demonstrates a thread-safe method that adds to a
' running total.  
Imports System.Threading

Public Class ThreadSafe
    ' Field totalValue contains a running total that can be updated
    ' by multiple threads. It must be protected from unsynchronized 
    ' access.
    Private totalValue As Single = 0.0

    ' The Total property returns the running total.
    Public ReadOnly Property Total As Single
        Get
            Return totalValue
        End Get
    End Property

    ' AddToTotal safely adds a value to the running total.
    Public Function AddToTotal(ByVal addend As Single) As Single
        Dim initialValue, computedValue As Single
        Do
            ' Save the current running total in a local variable.
            initialValue = totalValue

            ' Add the new value to the running total.
            computedValue = initialValue + addend

            ' CompareExchange compares totalValue to initialValue. If
            ' they are not equal, then another thread has updated the
            ' running total since this loop started. CompareExchange
            ' does not update totalValue. CompareExchange returns the
            ' contents of totalValue, which do not equal initialValue,
            ' so the loop executes again.
        Loop While initialValue <> Interlocked.CompareExchange( _
            totalValue, computedValue, initialValue)
        ' If no other thread updated the running total, then 
        ' totalValue and initialValue are equal when CompareExchange
        ' compares them, and computedValue is stored in totalValue.
        ' CompareExchange returns the value that was in totalValue
        ' before the update, which is equal to initialValue, so the 
        ' loop ends.

        ' The function returns computedValue, not totalValue, because
        ' totalValue could be changed by another thread between
        ' the time the loop ends and the function returns.
        Return computedValue
    End Function
End Class

Public Class Test
    ' Create an instance of the ThreadSafe class to test.
    Private Shared ts As New ThreadSafe()
    Private Shared control As Single

    Private Shared r As New Random()
    Private Shared mre As New ManualResetEvent(false)

    <MTAThread> _
    Public Shared Sub Main()
        ' Create two threads, name them, and start them. The
        ' threads will block on mre.
        Dim t1 As New Thread(AddressOf TestThread)
        t1.Name = "Thread 1"
        t1.Start()
        Dim t2 As New Thread(AddressOf TestThread)
        t2.Name = "Thread 2"
        t2.Start()

        ' Now let the threads begin adding random numbers to 
        ' the total.
        mre.Set()
        
        ' Wait until all the threads are done.
        t1.Join()
        t2.Join()

        Console.WriteLine("Thread safe: {0}  Ordinary Single: {1}", ts.Total, control)
    End Sub

    Private Shared Sub TestThread()
        ' Wait until the signal.
        mre.WaitOne()

        For i As Integer = 1 to 1000000
            ' Add to the running total in the ThreadSafe instance, and
            ' to an ordinary Single.
            '
            Dim testValue As Single = r.NextDouble()
            control += testValue
            ts.AddToTotal(testValue)
        Next
    End Sub
End Class

' On a dual-processor computer, this code example produces output 
' similar to the following:
'
'Thread safe: 17039.57  Ordinary Single: 15706.44

Hinweise

Wenn comparand und der Wert in location1 gleich sind, wird value in location1gespeichert. Andernfalls wird kein Vorgang ausgeführt. Die Vergleichs- und Austauschvorgänge werden als atome Operation durchgeführt. Der Rückgabewert von CompareExchange ist der ursprüngliche Wert in location1, unabhängig davon, ob der Austausch stattfindet.

Weitere Informationen

• verwalteten Threading-
• Übersicht über Synchronisierungsgrundtypen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.CoreCLR.cs

public:
 static System::Object ^ CompareExchange(System::Object ^ % location1, System::Object ^ value, System::Object ^ comparand);

public static object CompareExchange (ref object location1, object value, object comparand);

public static object? CompareExchange (ref object? location1, object? value, object? comparand);

static member CompareExchange : obj * obj * obj -> obj

Public Shared Function CompareExchange (ByRef location1 As Object, value As Object, comparand As Object) As Object

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Hinweise

Wenn comparand und das Objekt in location1 durch Verweis gleich sind, wird value in location1gespeichert. Andernfalls wird kein Vorgang ausgeführt. Die Vergleichs- und Austauschvorgänge werden als atome Operation durchgeführt. Der Rückgabewert von CompareExchange ist der ursprüngliche Wert in location1, unabhängig davon, ob der Austausch stattfindet.

Weitere Informationen

• verwalteten Threading-
• Übersicht über Synchronisierungsgrundtypen

public:
 static System::SByte CompareExchange(System::SByte % location1, System::SByte value, System::SByte comparand);

[System.CLSCompliant(false)]
public static sbyte CompareExchange (ref sbyte location1, sbyte value, sbyte comparand);

[<System.CLSCompliant(false)>]
static member CompareExchange : sbyte * sbyte * sbyte -> sbyte

Public Shared Function CompareExchange (ByRef location1 As SByte, value As SByte, comparand As SByte) As SByte

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Attribute

CLSCompliantAttribute

Ausnahmen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.CoreCLR.cs

public:
 static long CompareExchange(long % location1, long value, long comparand);

public static long CompareExchange (ref long location1, long value, long comparand);

static member CompareExchange : int64 * int64 * int64 -> int64

Public Shared Function CompareExchange (ByRef location1 As Long, value As Long, comparand As Long) As Long

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Hinweise

Wenn comparand und der Wert in location1 gleich sind, wird value in location1gespeichert. Andernfalls wird kein Vorgang ausgeführt. Die Vergleichs- und Austauschvorgänge werden als atome Operation durchgeführt. Der Rückgabewert von CompareExchange ist der ursprüngliche Wert in location1, unabhängig davon, ob der Austausch stattfindet.

Weitere Informationen

• verwalteten Threading-
• Übersicht über Synchronisierungsgrundtypen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.CoreCLR.cs

public:
 static int CompareExchange(int % location1, int value, int comparand);

public static int CompareExchange (ref int location1, int value, int comparand);

static member CompareExchange : int * int * int -> int

Public Shared Function CompareExchange (ByRef location1 As Integer, value As Integer, comparand As Integer) As Integer

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Beispiele

Im folgenden Codebeispiel wird eine threadsichere Methode veranschaulicht, die eine laufende Summe ansammelt. Der Anfangswert der laufenden Summe wird gespeichert, und dann wird die CompareExchange Methode verwendet, um die neu berechnete Summe mit der alten Summe auszutauschen. Wenn der Rückgabewert nicht dem gespeicherten Wert der laufenden Summe entspricht, hat ein anderer Thread die Summe in der Zwischenzeit aktualisiert. In diesem Fall muss der Versuch, die laufende Summe zu aktualisieren, wiederholt werden.

// This example demonstrates a thread-safe method that adds to a
// running total.  It cannot be run directly.  You can compile it
// as a library, or add the class to a project.
#using <system.dll>

using namespace System::Threading;
public ref class ThreadSafe
{
private:

   // totalValue contains a running total that can be updated
   // by multiple threads. It must be protected from unsynchronized 
   // access.
   int totalValue;

public:

   property int Total 
   {

      // The Total property returns the running total.
      int get()
      {
         return totalValue;
      }

   }

   // AddToTotal safely adds a value to the running total.
   int AddToTotal( int addend )
   {
      int initialValue;
      int computedValue;
      do
      {
         
         // Save the current running total in a local variable.
         initialValue = totalValue;
         
         // Add the new value to the running total.
         computedValue = initialValue + addend;
         
         // CompareExchange compares totalValue to initialValue. If
         // they are not equal, then another thread has updated the
         // running total since this loop started. CompareExchange
         // does not update totalValue. CompareExchange returns the
         // contents of totalValue, which do not equal initialValue,
         // so the loop executes again.
      }
      while ( initialValue != Interlocked::CompareExchange( totalValue, computedValue, initialValue ) );

      
      // If no other thread updated the running total, then 
      // totalValue and initialValue are equal when CompareExchange
      // compares them, and computedValue is stored in totalValue.
      // CompareExchange returns the value that was in totalValue
      // before the update, which is equal to initialValue, so the 
      // loop ends.
      // The function returns computedValue, not totalValue, because
      // totalValue could be changed by another thread between
      // the time the loop ends and the function returns.
      return computedValue;
   }

};

// This example demonstrates a thread-safe method that adds to a
// running total.  It cannot be run directly.  You can compile it
// as a library, or add the class to a project.
using System.Threading;

public class ThreadSafe {
    // totalValue contains a running total that can be updated
    // by multiple threads. It must be protected from unsynchronized 
    // access.
    private int totalValue = 0;

    // The Total property returns the running total.
    public int Total {
        get { return totalValue; }
    }

    // AddToTotal safely adds a value to the running total.
    public int AddToTotal(int addend) {
        int initialValue, computedValue;
        do {
            // Save the current running total in a local variable.
            initialValue = totalValue;

            // Add the new value to the running total.
            computedValue = initialValue + addend;

            // CompareExchange compares totalValue to initialValue. If
            // they are not equal, then another thread has updated the
            // running total since this loop started. CompareExchange
            // does not update totalValue. CompareExchange returns the
            // contents of totalValue, which do not equal initialValue,
            // so the loop executes again.
        } while (initialValue != Interlocked.CompareExchange(
            ref totalValue, computedValue, initialValue));
        // If no other thread updated the running total, then 
        // totalValue and initialValue are equal when CompareExchange
        // compares them, and computedValue is stored in totalValue.
        // CompareExchange returns the value that was in totalValue
        // before the update, which is equal to initialValue, so the 
        // loop ends.

        // The function returns computedValue, not totalValue, because
        // totalValue could be changed by another thread between
        // the time the loop ends and the function returns.
        return computedValue;
    }
}

' This example demonstrates a thread-safe method that adds to a
' running total.  It cannot be run directly.  You can compile it
' as a library, or add the class to a project.
Imports System.Threading

Public Class ThreadSafe
    ' Field totalValue contains a running total that can be updated
    ' by multiple threads. It must be protected from unsynchronized 
    ' access.
    Private totalValue As Integer = 0

    ' The Total property returns the running total.
    Public ReadOnly Property Total As Integer
        Get
            Return totalValue
        End Get
    End Property

    ' AddToTotal safely adds a value to the running total.
    Public Function AddToTotal(ByVal addend As Integer) As Integer
        Dim initialValue, computedValue As Integer
        Do
            ' Save the current running total in a local variable.
            initialValue = totalValue

            ' Add the new value to the running total.
            computedValue = initialValue + addend

            ' CompareExchange compares totalValue to initialValue. If
            ' they are not equal, then another thread has updated the
            ' running total since this loop started. CompareExchange
            ' does not update totalValue. CompareExchange returns the
            ' contents of totalValue, which do not equal initialValue,
            ' so the loop executes again.
        Loop While initialValue <> Interlocked.CompareExchange( _
            totalValue, computedValue, initialValue)
        ' If no other thread updated the running total, then 
        ' totalValue and initialValue are equal when CompareExchange
        ' compares them, and computedValue is stored in totalValue.
        ' CompareExchange returns the value that was in totalValue
        ' before the update, which is equal to initialValue, so the 
        ' loop ends.

        ' The function returns computedValue, not totalValue, because
        ' totalValue could be changed by another thread between
        ' the time the loop ends and the function returns.
        Return computedValue
    End Function
End Class

Hinweise

Wenn comparand und der Wert in location1 gleich sind, wird value in location1gespeichert. Andernfalls wird kein Vorgang ausgeführt. Die Vergleichs- und Austauschvorgänge werden als atome Operation durchgeführt. Der Rückgabewert von CompareExchange ist der ursprüngliche Wert in location1, unabhängig davon, ob der Austausch stattfindet.

Weitere Informationen

• verwalteten Threading-
• Übersicht über Synchronisierungsgrundtypen

public:
 static short CompareExchange(short % location1, short value, short comparand);

public static short CompareExchange (ref short location1, short value, short comparand);

static member CompareExchange : int16 * int16 * int16 -> int16

Public Shared Function CompareExchange (ByRef location1 As Short, value As Short, comparand As Short) As Short

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

public:
 static double CompareExchange(double % location1, double value, double comparand);

public static double CompareExchange (ref double location1, double value, double comparand);

static member CompareExchange : double * double * double -> double

Public Shared Function CompareExchange (ByRef location1 As Double, value As Double, comparand As Double) As Double

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Beispiele

Im folgenden Codebeispiel wird eine threadsichere Methode veranschaulicht, die eine laufende Summe von Double Werten ansammelt. Zwei Threads fügen eine Reihe von Double Werten mithilfe der threadsicheren Methode und gewöhnlichen Hinzufügung hinzu, und wenn die Threads die Summen abschließen, werden verglichen. Auf einem Dualprozessorcomputer gibt es einen erheblichen Unterschied in den Summen.

In der threadsicheren Methode wird der Anfangswert der ausgeführten Summe gespeichert, und dann wird die CompareExchange Methode verwendet, um die neu berechnete Summe mit der alten Summe auszutauschen. Wenn der Rückgabewert nicht dem gespeicherten Wert der laufenden Summe entspricht, hat ein anderer Thread die Summe in der Zwischenzeit aktualisiert. In diesem Fall muss der Versuch, die laufende Summe zu aktualisieren, wiederholt werden.

// This example demonstrates a thread-safe method that adds to a
// running total.  
using System;
using System.Threading;

public class ThreadSafe
{
    // Field totalValue contains a running total that can be updated
    // by multiple threads. It must be protected from unsynchronized 
    // access.
    private double totalValue = 0.0;

    // The Total property returns the running total.
    public double Total { get { return totalValue; }}

    // AddToTotal safely adds a value to the running total.
    public double AddToTotal(double addend)
    {
        double initialValue, computedValue;
        do
        {
            // Save the current running total in a local variable.
            initialValue = totalValue;

            // Add the new value to the running total.
            computedValue = initialValue + addend;

            // CompareExchange compares totalValue to initialValue. If
            // they are not equal, then another thread has updated the
            // running total since this loop started. CompareExchange
            // does not update totalValue. CompareExchange returns the
            // contents of totalValue, which do not equal initialValue,
            // so the loop executes again.
        }
        while (initialValue != Interlocked.CompareExchange(ref totalValue, 
            computedValue, initialValue));
        // If no other thread updated the running total, then 
        // totalValue and initialValue are equal when CompareExchange
        // compares them, and computedValue is stored in totalValue.
        // CompareExchange returns the value that was in totalValue
        // before the update, which is equal to initialValue, so the 
        // loop ends.

        // The function returns computedValue, not totalValue, because
        // totalValue could be changed by another thread between
        // the time the loop ends and the function returns.
        return computedValue;
    }
}

public class Test
{
    // Create an instance of the ThreadSafe class to test.
    private static ThreadSafe ts = new ThreadSafe();
    private static double control;

    private static Random r = new Random();
    private static ManualResetEvent mre = new ManualResetEvent(false);

    public static void Main()
    {
        // Create two threads, name them, and start them. The
        // thread will block on mre.
        Thread t1 = new Thread(TestThread);
        t1.Name = "Thread 1";
        t1.Start();
        Thread t2 = new Thread(TestThread);
        t2.Name = "Thread 2";
        t2.Start();

        // Now let the threads begin adding random numbers to 
        // the total.
        mre.Set();
        
        // Wait until all the threads are done.
        t1.Join();
        t2.Join();

        Console.WriteLine("Thread safe: {0}  Ordinary Double: {1}", 
            ts.Total, control);
    }

    private static void TestThread()
    {
        // Wait until the signal.
        mre.WaitOne();

        for(int i = 1; i <= 1000000; i++)
        {
            // Add to the running total in the ThreadSafe instance, and
            // to an ordinary double.
            //
            double testValue = r.NextDouble();
            control += testValue;
            ts.AddToTotal(testValue);
        }
    }
}

/* On a dual-processor computer, this code example produces output 
   similar to the following:

Thread safe: 998068.049623744  Ordinary Double: 759775.417190589
 */

' This example demonstrates a thread-safe method that adds to a
' running total.  
Imports System.Threading

Public Class ThreadSafe
    ' Field totalValue contains a running total that can be updated
    ' by multiple threads. It must be protected from unsynchronized 
    ' access.
    Private totalValue As Double = 0.0

    ' The Total property returns the running total.
    Public ReadOnly Property Total As Double
        Get
            Return totalValue
        End Get
    End Property

    ' AddToTotal safely adds a value to the running total.
    Public Function AddToTotal(ByVal addend As Double) As Double
        Dim initialValue, computedValue As Double
        Do
            ' Save the current running total in a local variable.
            initialValue = totalValue

            ' Add the new value to the running total.
            computedValue = initialValue + addend

            ' CompareExchange compares totalValue to initialValue. If
            ' they are not equal, then another thread has updated the
            ' running total since this loop started. CompareExchange
            ' does not update totalValue. CompareExchange returns the
            ' contents of totalValue, which do not equal initialValue,
            ' so the loop executes again.
        Loop While initialValue <> Interlocked.CompareExchange( _
            totalValue, computedValue, initialValue)
        ' If no other thread updated the running total, then 
        ' totalValue and initialValue are equal when CompareExchange
        ' compares them, and computedValue is stored in totalValue.
        ' CompareExchange returns the value that was in totalValue
        ' before the update, which is equal to initialValue, so the 
        ' loop ends.

        ' The function returns computedValue, not totalValue, because
        ' totalValue could be changed by another thread between
        ' the time the loop ends and the function returns.
        Return computedValue
    End Function
End Class

Public Class Test
    ' Create an instance of the ThreadSafe class to test.
    Private Shared ts As New ThreadSafe()
    Private Shared control As Double

    Private Shared r As New Random()
    Private Shared mre As New ManualResetEvent(false)

    <MTAThread> _
    Public Shared Sub Main()
        ' Create two threads, name them, and start them. The
        ' threads will block on mre.
        Dim t1 As New Thread(AddressOf TestThread)
        t1.Name = "Thread 1"
        t1.Start()
        Dim t2 As New Thread(AddressOf TestThread)
        t2.Name = "Thread 2"
        t2.Start()

        ' Now let the threads begin adding random numbers to 
        ' the total.
        mre.Set()
        
        ' Wait until all the threads are done.
        t1.Join()
        t2.Join()

        Console.WriteLine("Thread safe: {0}  Ordinary Double: {1}", ts.Total, control)
    End Sub

    Private Shared Sub TestThread()
        ' Wait until the signal.
        mre.WaitOne()

        For i As Integer = 1 to 1000000
            ' Add to the running total in the ThreadSafe instance, and
            ' to an ordinary double.
            '
            Dim testValue As Double = r.NextDouble
            control += testValue
            ts.AddToTotal(testValue)
        Next
    End Sub
End Class

' On a dual-processor computer, this code example produces output 
' similar to the following:
'
'Thread safe: 998068.049623744  Ordinary Double: 759775.417190589

Hinweise

Wenn comparand und der Wert in location1 gleich sind, wird value in location1gespeichert. Andernfalls wird kein Vorgang ausgeführt. Die Vergleichs- und Austauschvorgänge werden als atome Operation durchgeführt. Der Rückgabewert von CompareExchange ist der ursprüngliche Wert in location1, unabhängig davon, ob der Austausch stattfindet.

Weitere Informationen

• verwalteten Threading-
• Übersicht über Synchronisierungsgrundtypen

public:
 static System::Byte CompareExchange(System::Byte % location1, System::Byte value, System::Byte comparand);

public static byte CompareExchange (ref byte location1, byte value, byte comparand);

static member CompareExchange : byte * byte * byte -> byte

Public Shared Function CompareExchange (ByRef location1 As Byte, value As Byte, comparand As Byte) As Byte

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

Quelle:

Interlocked.cs

public:
 static IntPtr CompareExchange(IntPtr % location1, IntPtr value, IntPtr comparand);

public static IntPtr CompareExchange (ref IntPtr location1, IntPtr value, IntPtr comparand);

static member CompareExchange : nativeint * nativeint * nativeint -> nativeint

Public Shared Function CompareExchange (ByRef location1 As IntPtr, value As IntPtr, comparand As IntPtr) As IntPtr

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Ausnahmen

Hinweise

Wenn comparand und der Wert in location1 gleich sind, wird value in location1gespeichert. Andernfalls wird kein Vorgang ausgeführt. Die Vergleichs- und Austauschvorgänge werden als atome Operation durchgeführt. Der Rückgabewert dieser Methode ist der ursprüngliche Wert in location1, unabhängig davon, ob der Austausch stattfindet.

Weitere Informationen

• verwalteten Threading-
• Übersicht über Synchronisierungsgrundtypen

Quelle:

Interlocked.CoreCLR.cs

Quelle:

Interlocked.CoreCLR.cs

Quelle:

Interlocked.CoreCLR.cs

public:
generic <typename T>
 where T : class static T CompareExchange(T % location1, T value, T comparand);

public:
generic <typename T>
 static T CompareExchange(T % location1, T value, T comparand);

public static T CompareExchange<T> (ref T location1, T value, T comparand) where T : class;

public static T CompareExchange<T> (ref T location1, T value, T comparand);

[System.Runtime.InteropServices.ComVisible(false)]
public static T CompareExchange<T> (ref T location1, T value, T comparand) where T : class;

static member CompareExchange : 'T * 'T * 'T -> 'T (requires 'T : null)

static member CompareExchange : 'T * 'T * 'T -> 'T

[<System.Runtime.InteropServices.ComVisible(false)>]
static member CompareExchange : 'T * 'T * 'T -> 'T (requires 'T : null)

Public Shared Function CompareExchange(Of T As Class) (ByRef location1 As T, value As T, comparand As T) As T

Public Shared Function CompareExchange(Of T) (ByRef location1 As T, value As T, comparand As T) As T

Typparameter

Parameter

Gibt zurück

Der ursprüngliche Wert in location1.

Attribute

ComVisibleAttribute

Ausnahmen

Hinweise

Wenn comparand und der Wert in location1 gleich bezugsgleich sind, wird value in location1gespeichert. Andernfalls wird kein Vorgang ausgeführt. Der Vergleich und der Austausch werden als Atomoperation durchgeführt. Der Rückgabewert dieser Methode ist der ursprüngliche Wert in location1, unabhängig davon, ob der Austausch stattfindet.

Diese Methode unterstützt nur Referenztypen. Es gibt Überladungen der CompareExchange-Methode für die Werttypen Int32, Int64, IntPtr, Singleund Double, aber es gibt keine Unterstützung für andere Werttypen.