Interlocked.Exchange 方法

定义

命名空间:

System.Threading

程序集:

System.Threading.dll

以原子操作的形式将变量设置为指定的值。

重载

Exchange(UInt32, UInt32)	以原子操作的形式，将 32 位无符号整数设置为指定的值并返回原始值。
Exchange(Single, Single)	以原子操作的形式，将单精度浮点数设置为指定的值并返回原始值。
Exchange(UIntPtr, UIntPtr)	以原子操作的形式，将平台特定的句柄或指针设置为指定的值并返回原始值。
Exchange(UInt64, UInt64)	以原子操作的形式，将 64 位无符号整数设置为指定的值并返回原始值。
Exchange(IntPtr, IntPtr)	以原子操作的形式，将平台特定的句柄或指针设置为指定的值并返回原始值。
Exchange(Int64, Int64)	以原子操作的形式，将 64 位有符号整数设置为指定的值并返回原始值。
Exchange(Int32, Int32)	以原子操作的形式，将 32 位有符号整数设置为指定的值并返回原始值。
Exchange(Double, Double)	以原子操作的形式，将双精度浮点数设置为指定的值并返回原始值。
Exchange(Object, Object)	以原子操作的形式，将对象设置为指定的值并返回对原始对象的引用。
Exchange<T>(T, T)	以原子操作的形式，将指定类型 T 的变量设置为指定的值并返回原始值。

Exchange(UInt32, UInt32)

Source:

Interlocked.cs

重要

此 API 不符合 CLS。

以原子操作的形式，将 32 位无符号整数设置为指定的值并返回原始值。

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

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

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

Public Shared Function Exchange (ByRef location1 As UInteger, value As UInteger) As UInteger

参数

location1

UInt32

要设置为指定值的变量。

value

UInt32

location1 参数要设置成的值。

返回

UInt32

location1 的原始值。

属性

CLSCompliantAttribute

例外

NullReferenceException

location1 的地址是一个 null 指针。

Exchange(Single, Single)

Source:

Interlocked.cs

以原子操作的形式，将单精度浮点数设置为指定的值并返回原始值。

public:
 static float Exchange(float % location1, float value);

public static float Exchange (ref float location1, float value);

static member Exchange : single * single -> single

Public Shared Function Exchange (ByRef location1 As Single, value As Single) As Single

参数

location1

Single

要设置为指定值的变量。

value

Single

location1 参数要设置成的值。

返回

Single

location1 的原始值。

例外

NullReferenceException

location1 的地址是一个 null 指针。

另请参阅

• 托管线程
• 同步基元概述

Exchange(UIntPtr, UIntPtr)

Source:

Interlocked.cs

重要

此 API 不符合 CLS。

以原子操作的形式，将平台特定的句柄或指针设置为指定的值并返回原始值。

public:
 static UIntPtr Exchange(UIntPtr % location1, UIntPtr value);

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

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

Public Shared Function Exchange (ByRef location1 As UIntPtr, value As UIntPtr) As UIntPtr

参数

location1

UIntPtr

unativeint

要设置为指定值的变量。

value

UIntPtr

unativeint

location1 参数要设置成的值。

返回

UIntPtr

unativeint

location1 的原始值。

属性

CLSCompliantAttribute

例外

NullReferenceException

location1 的地址是一个 null 指针。

Exchange(UInt64, UInt64)

Source:

Interlocked.cs

重要

此 API 不符合 CLS。

以原子操作的形式，将 64 位无符号整数设置为指定的值并返回原始值。

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

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

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

Public Shared Function Exchange (ByRef location1 As ULong, value As ULong) As ULong

参数

location1

UInt64

要设置为指定值的变量。

value

UInt64

location1 参数要设置成的值。

返回

UInt64

location1 的原始值。

属性

CLSCompliantAttribute

例外

NullReferenceException

location1 的地址是一个 null 指针。

Exchange(IntPtr, IntPtr)

Source:

Interlocked.cs

以原子操作的形式，将平台特定的句柄或指针设置为指定的值并返回原始值。

public:
 static IntPtr Exchange(IntPtr % location1, IntPtr value);

public static IntPtr Exchange (ref IntPtr location1, IntPtr value);

static member Exchange : nativeint * nativeint -> nativeint

Public Shared Function Exchange (ByRef location1 As IntPtr, value As IntPtr) As IntPtr

参数

location1

IntPtr

nativeint

要设置为指定值的变量。

value

IntPtr

nativeint

location1 参数要设置成的值。

返回

IntPtr

nativeint

location1 的原始值。

例外

NullReferenceException

location1 的地址是一个 null 指针。

另请参阅

• 托管线程
• 同步基元概述

Exchange(Int64, Int64)

Source:

Interlocked.cs

以原子操作的形式，将 64 位有符号整数设置为指定的值并返回原始值。

public:
 static long Exchange(long % location1, long value);

public static long Exchange (ref long location1, long value);

static member Exchange : int64 * int64 -> int64

Public Shared Function Exchange (ByRef location1 As Long, value As Long) As Long

参数

location1

Int64

要设置为指定值的变量。

value

Int64

location1 参数要设置成的值。

返回

Int64

location1 的原始值。

例外

NullReferenceException

location1 的地址是一个 null 指针。

另请参阅

• 托管线程
• 同步基元概述

Exchange(Int32, Int32)

Source:

Interlocked.cs

以原子操作的形式，将 32 位有符号整数设置为指定的值并返回原始值。

public:
 static int Exchange(int % location1, int value);

public static int Exchange (ref int location1, int value);

static member Exchange : int * int -> int

Public Shared Function Exchange (ByRef location1 As Integer, value As Integer) As Integer

参数

location1

Int32

要设置为指定值的变量。

value

Int32

location1 参数要设置成的值。

返回

Int32

location1 的原始值。

例外

ArgumentNullException

location1 的地址是一个 null 指针。

NullReferenceException

location1 的地址是一个 null 指针。

示例

下面的代码示例演示线程安全资源锁定机制。

using namespace System;
using namespace System::Threading;

const int numThreads = 10;
const int numThreadIterations = 5;
ref class MyInterlockedExchangeExampleClass
{
public:
   static void MyThreadProc()
   {
      for ( int i = 0; i < numThreadIterations; i++ )
      {
         UseResource();
         
         //Wait 1 second before next attempt.
         Thread::Sleep( 1000 );

      }
   }


private:
   //A simple method that denies reentrancy.
   static bool UseResource()
   {
      
      //0 indicates that the method is not in use.
      if ( 0 == Interlocked::Exchange( usingResource, 1 ) )
      {
         Console::WriteLine( " {0} acquired the lock", Thread::CurrentThread->Name );
         
         //Code to access a resource that is not thread safe would go here.
         //Simulate some work
         Thread::Sleep( 500 );
         Console::WriteLine( " {0} exiting lock", Thread::CurrentThread->Name );
         
         //Release the lock
         Interlocked::Exchange( usingResource, 0 );
         return true;
      }
      else
      {
         Console::WriteLine( " {0} was denied the lock", Thread::CurrentThread->Name );
         return false;
      }
   }


   //0 for false, 1 for true.
   static int usingResource;
};

int main()
{
   Thread^ myThread;
   Random^ rnd = gcnew Random;
   for ( int i = 0; i < numThreads; i++ )
   {
      myThread = gcnew Thread( gcnew ThreadStart( MyInterlockedExchangeExampleClass::MyThreadProc ) );
      myThread->Name = String::Format( "Thread {0}", i + 1 );
      
      //Wait a random amount of time before starting next thread.
      Thread::Sleep( rnd->Next( 0, 1000 ) );
      myThread->Start();

   }
}

using System;
using System.Threading;

namespace InterlockedExchange_Example
{
    class MyInterlockedExchangeExampleClass
    {
        //0 for false, 1 for true.
        private static int usingResource = 0;

        private const int numThreadIterations = 5;
        private const int numThreads = 10;

        static void Main()
        {
            Thread myThread;
            Random rnd = new Random();

            for(int i = 0; i < numThreads; i++)
            {
                myThread = new Thread(new ThreadStart(MyThreadProc));
                myThread.Name = String.Format("Thread{0}", i + 1);
            
                //Wait a random amount of time before starting next thread.
                Thread.Sleep(rnd.Next(0, 1000));
                myThread.Start();
            }
        }

        private static void MyThreadProc()
        {
            for(int i = 0; i < numThreadIterations; i++)
            {
                UseResource();
            
                //Wait 1 second before next attempt.
                Thread.Sleep(1000);
            }
        }

        //A simple method that denies reentrancy.
        static bool UseResource()
        {
            //0 indicates that the method is not in use.
            if(0 == Interlocked.Exchange(ref usingResource, 1))
            {
                Console.WriteLine("{0} acquired the lock", Thread.CurrentThread.Name);
            
                //Code to access a resource that is not thread safe would go here.
            
                //Simulate some work
                Thread.Sleep(500);

                Console.WriteLine("{0} exiting lock", Thread.CurrentThread.Name);
            
                //Release the lock
                Interlocked.Exchange(ref usingResource, 0);
                return true;
            }
            else
            {
                Console.WriteLine("   {0} was denied the lock", Thread.CurrentThread.Name);
                return false;
            }
        }
    }
}

Imports System.Threading

Namespace InterlockedExchange_Example
    Class MyInterlockedExchangeExampleClass
        '0 for false, 1 for true.
        Private Shared usingResource As Integer = 0

        Private Const numThreadIterations As Integer = 5
        Private Const numThreads As Integer = 10

        <MTAThread> _
        Shared Sub Main()
            Dim myThread As Thread
            Dim rnd As New Random()

            Dim i As Integer
            For i = 0 To numThreads - 1
                myThread = New Thread(AddressOf MyThreadProc)
                myThread.Name = String.Format("Thread{0}", i + 1)

                'Wait a random amount of time before starting next thread.
                Thread.Sleep(rnd.Next(0, 1000))
                myThread.Start()
            Next i
        End Sub

        Private Shared Sub MyThreadProc()
            Dim i As Integer
            For i = 0 To numThreadIterations - 1
                UseResource()

                'Wait 1 second before next attempt.
                Thread.Sleep(1000)
            Next i
        End Sub 

        'A simple method that denies reentrancy.
        Shared Function UseResource() As Boolean
            '0 indicates that the method is not in use.
            If 0 = Interlocked.Exchange(usingResource, 1) Then
                Console.WriteLine("{0} acquired the lock", Thread.CurrentThread.Name)

                'Code to access a resource that is not thread safe would go here.
                'Simulate some work
                Thread.Sleep(500)

                Console.WriteLine("{0} exiting lock", Thread.CurrentThread.Name)

                'Release the lock
                Interlocked.Exchange(usingResource, 0)
                Return True
            Else
                Console.WriteLine("   {0} was denied the lock", Thread.CurrentThread.Name)
                Return False
            End If
        End Function 
    End Class 
End Namespace

另请参阅

• 托管线程
• 同步基元概述

Exchange(Double, Double)

Source:

Interlocked.cs

以原子操作的形式，将双精度浮点数设置为指定的值并返回原始值。

public:
 static double Exchange(double % location1, double value);

public static double Exchange (ref double location1, double value);

static member Exchange : double * double -> double

Public Shared Function Exchange (ByRef location1 As Double, value As Double) As Double

参数

location1

Double

要设置为指定值的变量。

value

Double

location1 参数要设置成的值。

返回

Double

location1 的原始值。

例外

NullReferenceException

location1 的地址是一个 null 指针。

另请参阅

• 托管线程
• 同步基元概述

Exchange(Object, Object)

Source:

Interlocked.cs

以原子操作的形式，将对象设置为指定的值并返回对原始对象的引用。

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

public static object? Exchange (ref object? location1, object? value);

static member Exchange : obj * obj -> obj

Public Shared Function Exchange (ByRef location1 As Object, value As Object) As Object

参数

location1

Object

要设置为指定值的变量。

value

Object

location1 参数要设置成的值。

返回

Object

location1 的原始值。

例外

ArgumentNullException

location1 的地址是一个 null 指针。

NullReferenceException

location1 的地址是一个 null 指针。

注解

重要

从 .NET Framework 2.0 开始，Exchange<T>(T, T) 方法重载为引用类型提供类型安全的替代项。 建议调用它，而不是此重载。

另请参阅

• 托管线程
• 同步基元概述

Exchange<T>(T, T)

Source:

Interlocked.CoreCLR.cs

以原子操作的形式，将指定类型 T 的变量设置为指定的值并返回原始值。

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

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

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

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

类型参数

T

要用于 location1 和 value 的类型。 此类型必须是引用类型。

参数

location1

T

要设置为指定值的变量。 这是一个引用参数（C# 中为 ref，Visual Basic 中为 ByRef）。

value

T

location1 参数要设置成的值。

返回

T

location1 的原始值。

例外

NullReferenceException

location1 的地址是一个 null 指针。

注解

此方法仅支持引用类型。 方法重载Exchange适用于 Int32、、Int64、 IntPtrSingle和 Double 值类型，但不支持其他值类型。

注意

此方法重载优于 Exchange(Object, Object) 方法重载，因为后者需要对目标对象 进行后期绑定访问。