RegisteredWaitHandle 类

定义

命名空间:

System.Threading

程序集:

System.Threading.ThreadPool.dll

Source:

RegisteredWaitHandle.Unix.cs

表示在调用 RegisterWaitForSingleObject(WaitHandle, WaitOrTimerCallback, Object, UInt32, Boolean) 时已注册的句柄。 此类不能被继承。

public ref class RegisteredWaitHandle sealed : MarshalByRefObject

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public sealed class RegisteredWaitHandle : MarshalByRefObject

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
type RegisteredWaitHandle = class
    inherit MarshalByRefObject

Public NotInheritable Class RegisteredWaitHandle
Inherits MarshalByRefObject

继承

Object

MarshalByRefObject

RegisteredWaitHandle

属性

UnsupportedOSPlatformAttribute

示例

以下示例演示如何使用 RegisteredWaitHandle 来确定调用回调方法的原因，以及如何在回调因等待句柄被发出信号而发生时取消注册任务。

该示例还演示了在 RegisterWaitForSingleObject 发出指定等待句柄信号时如何使用 方法执行指定的回调方法。 在此示例中，回调方法是 WaitProc，等待句柄是 AutoResetEvent。

该示例定义了一个 TaskInfo 类，用于保存在执行回调时传递给回调的信息。 该示例创建 一个 TaskInfo 对象，并为其分配一些字符串数据。 RegisteredWaitHandle方法返回RegisterWaitForSingleObject的 将Handle分配给 对象的 字段TaskInfo，以便回调方法有权访问 RegisteredWaitHandle。

除了将 指定 TaskInfo 为要传递给回调方法的对象外，对 RegisterWaitForSingleObject 方法的调用还 AutoResetEvent 指定任务将等待的 、 WaitOrTimerCallback 表示回调方法的 WaitProc 委托、一秒超时间隔和多个回调。

当主线程通过调用其 Set 方法发出信号AutoResetEvent时，WaitOrTimerCallback将调用 委托。 方法 WaitProc 测试 RegisteredWaitHandle 以确定是否发生超时。 如果调用回调是因为等待句柄已发出信号，则 WaitProc 方法将取消注册 RegisteredWaitHandle，从而停止其他回调。 如果超时，任务将继续等待。 方法 WaitProc 最后将消息打印到控制台。

using namespace System;
using namespace System::Threading;

// TaskInfo contains data that will be passed to the callback
// method.
public ref class TaskInfo
{
public:
   TaskInfo()
   {
      Handle = nullptr;
      OtherInfo = "default";
   }

   RegisteredWaitHandle^ Handle;
   String^ OtherInfo;
};

ref class Example
{
public:

   // The callback method executes when the registered wait times out,
   // or when the WaitHandle (in this case AutoResetEvent) is signaled.
   // WaitProc unregisters the WaitHandle the first time the event is 
   // signaled.
   static void WaitProc( Object^ state, bool timedOut )
   {
      
      // The state Object must be cast to the correct type, because the
      // signature of the WaitOrTimerCallback delegate specifies type
      // Object.
      TaskInfo^ ti = static_cast<TaskInfo^>(state);
      String^ cause = "TIMED OUT";
      if (  !timedOut )
      {
         cause = "SIGNALED";
         
         // If the callback method executes because the WaitHandle is
         // signaled, stop future execution of the callback method
         // by unregistering the WaitHandle.
         if ( ti->Handle != nullptr )
                  ti->Handle->Unregister( nullptr );
      }

      Console::WriteLine( "WaitProc( {0}) executes on thread {1}; cause = {2}.", ti->OtherInfo, Thread::CurrentThread->GetHashCode(), cause );
   }

};

int main()
{
   
   // The main thread uses AutoResetEvent to signal the
   // registered wait handle, which executes the callback
   // method.
   AutoResetEvent^ ev = gcnew AutoResetEvent( false );
   TaskInfo^ ti = gcnew TaskInfo;
   ti->OtherInfo = "First task";
   
   // The TaskInfo for the task includes the registered wait
   // handle returned by RegisterWaitForSingleObject.  This
   // allows the wait to be terminated when the object has
   // been signaled once (see WaitProc).
   ti->Handle = ThreadPool::RegisterWaitForSingleObject( ev, gcnew WaitOrTimerCallback( Example::WaitProc ), ti, 1000, false );
   
   // The main thread waits three seconds, to demonstrate the
   // time-outs on the queued thread, and then signals.
   Thread::Sleep( 3100 );
   Console::WriteLine( "Main thread signals." );
   ev->Set();
   
   // The main thread sleeps, which should give the callback
   // method time to execute.  If you comment out this line, the
   // program usually ends before the ThreadPool thread can execute.
   Thread::Sleep( 1000 );
   
   // If you start a thread yourself, you can wait for it to end
   // by calling Thread::Join.  This option is not available with 
   // thread pool threads.
   return 0;
}

using System;
using System.Threading;

// TaskInfo contains data that will be passed to the callback
// method.
public class TaskInfo {
    public RegisteredWaitHandle Handle = null;
    public string OtherInfo = "default";
}

public class Example {
    public static void Main(string[] args) {
        // The main thread uses AutoResetEvent to signal the
        // registered wait handle, which executes the callback
        // method.
        AutoResetEvent ev = new AutoResetEvent(false);

        TaskInfo ti = new TaskInfo();
        ti.OtherInfo = "First task";
        // The TaskInfo for the task includes the registered wait
        // handle returned by RegisterWaitForSingleObject.  This
        // allows the wait to be terminated when the object has
        // been signaled once (see WaitProc).
        ti.Handle = ThreadPool.RegisterWaitForSingleObject(
            ev,
            new WaitOrTimerCallback(WaitProc),
            ti,
            1000,
            false
        );

        // The main thread waits three seconds, to demonstrate the
        // time-outs on the queued thread, and then signals.
        Thread.Sleep(3100);
        Console.WriteLine("Main thread signals.");
        ev.Set();

        // The main thread sleeps, which should give the callback
        // method time to execute.  If you comment out this line, the
        // program usually ends before the ThreadPool thread can execute.
        Thread.Sleep(1000);
        // If you start a thread yourself, you can wait for it to end
        // by calling Thread.Join.  This option is not available with 
        // thread pool threads.
    }
   
    // The callback method executes when the registered wait times out,
    // or when the WaitHandle (in this case AutoResetEvent) is signaled.
    // WaitProc unregisters the WaitHandle the first time the event is 
    // signaled.
    public static void WaitProc(object state, bool timedOut) {
        // The state object must be cast to the correct type, because the
        // signature of the WaitOrTimerCallback delegate specifies type
        // Object.
        TaskInfo ti = (TaskInfo) state;

        string cause = "TIMED OUT";
        if (!timedOut) {
            cause = "SIGNALED";
            // If the callback method executes because the WaitHandle is
            // signaled, stop future execution of the callback method
            // by unregistering the WaitHandle.
            if (ti.Handle != null)
                ti.Handle.Unregister(null);
        } 

        Console.WriteLine("WaitProc( {0} ) executes on thread {1}; cause = {2}.",
            ti.OtherInfo, 
            Thread.CurrentThread.GetHashCode().ToString(), 
            cause
        );
    }
}

Imports System.Threading

' TaskInfo contains data that will be passed to the callback
' method.
Public Class TaskInfo
    public Handle As RegisteredWaitHandle = Nothing
    public OtherInfo As String = "default"
End Class

Public Class Example

    <MTAThread> _
    Public Shared Sub Main()
        ' The main thread uses AutoResetEvent to signal the
        ' registered wait handle, which executes the callback
        ' method.
        Dim ev As New AutoResetEvent(false)

        Dim ti As New TaskInfo()
        ti.OtherInfo = "First task"
        ' The TaskInfo for the task includes the registered wait
        ' handle returned by RegisterWaitForSingleObject.  This
        ' allows the wait to be terminated when the object has
        ' been signaled once (see WaitProc).
        ti.Handle = ThreadPool.RegisterWaitForSingleObject( _
            ev, _
            New WaitOrTimerCallback(AddressOf WaitProc), _
            ti, _
            1000, _
            false _
        )

        ' The main thread waits about three seconds, to demonstrate 
        ' the time-outs on the queued task, and then signals.
        Thread.Sleep(3100)
        Console.WriteLine("Main thread signals.")
        ev.Set()

        ' The main thread sleeps, which should give the callback
        ' method time to execute.  If you comment out this line, the
        ' program usually ends before the ThreadPool thread can execute.
        Thread.Sleep(1000)
        ' If you start a thread yourself, you can wait for it to end
        ' by calling Thread.Join.  This option is not available with 
        ' thread pool threads.
    End Sub
   
    ' The callback method executes when the registered wait times out,
    ' or when the WaitHandle (in this case AutoResetEvent) is signaled.
    ' WaitProc unregisters the WaitHandle the first time the event is 
    ' signaled.
    Public Shared Sub WaitProc(state As Object, timedOut As Boolean)
        ' The state object must be cast to the correct type, because the
        ' signature of the WaitOrTimerCallback delegate specifies type
        ' Object.
        Dim ti As TaskInfo = CType(state, TaskInfo)

        Dim cause As String = "TIMED OUT"
        If Not timedOut Then
            cause = "SIGNALED"
            ' If the callback method executes because the WaitHandle is
            ' signaled, stop future execution of the callback method
            ' by unregistering the WaitHandle.
            If Not ti.Handle Is Nothing Then
                ti.Handle.Unregister(Nothing)
            End If
        End If 

        Console.WriteLine("WaitProc( {0} ) executes on thread {1}; cause = {2}.", _
            ti.OtherInfo, _
            Thread.CurrentThread.GetHashCode().ToString(), _
            cause _
        )
    End Sub
End Class

方法

CreateObjRef(Type)	创建一个对象，该对象包含生成用于与远程对象进行通信的代理所需的全部相关信息。 (继承自 MarshalByRefObject)
Equals(Object)	确定指定对象是否等于当前对象。 (继承自 Object)
GetHashCode()	作为默认哈希函数。 (继承自 Object)
GetLifetimeService()	已过时. 检索控制此实例的生存期策略的当前生存期服务对象。 (继承自 MarshalByRefObject)
GetType()	获取当前实例的 Type。 (继承自 Object)
InitializeLifetimeService()	已过时. 获取生存期服务对象来控制此实例的生存期策略。 (继承自 MarshalByRefObject)
MemberwiseClone()	创建当前 Object 的浅表副本。 (继承自 Object)
MemberwiseClone(Boolean)	创建当前 MarshalByRefObject 对象的浅表副本。 (继承自 MarshalByRefObject)
ToString()	返回表示当前对象的字符串。 (继承自 Object)
Unregister(WaitHandle)	取消由 RegisterWaitForSingleObject(WaitHandle, WaitOrTimerCallback, Object, UInt32, Boolean) 方法发出的已注册等待操作。

线程安全性

此类型是线程安全的。

另请参阅

• 托管线程池