RegisteredWaitHandle 类

定义

表示在调用 RegisterWaitForSingleObject(WaitHandle, WaitOrTimerCallback, Object, UInt32, Boolean) 时已注册的句柄。Represents a handle that has been registered when calling RegisterWaitForSingleObject(WaitHandle, WaitOrTimerCallback, Object, UInt32, Boolean). 无法继承此类。This class cannot be inherited.

public ref class RegisteredWaitHandle sealed : MarshalByRefObject
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class RegisteredWaitHandle : MarshalByRefObject
type RegisteredWaitHandle = class
    inherit MarshalByRefObject
Public NotInheritable Class RegisteredWaitHandle
Inherits MarshalByRefObject
继承
RegisteredWaitHandle
属性

示例

下面的示例演示如何使用 RegisteredWaitHandle 来确定调用回调方法的原因,以及如果在等待句柄终止的情况下回调发生,如何取消注册任务。The following example shows how to use a RegisteredWaitHandle to determine why a callback method is called, and how to unregister a task if the callback occurred because the wait handle was signaled.

该示例还演示了如何使用 RegisterWaitForSingleObject 方法在指定的等待句柄收到信号时执行指定的回调方法。The example also shows how to use the RegisterWaitForSingleObject method to execute a specified callback method when a specified wait handle is signaled. 在此示例中,回调方法为 WaitProc,等待句柄是一个 AutoResetEventIn this example, the callback method is WaitProc, and the wait handle is an AutoResetEvent.

该示例定义了一个 TaskInfo 类,用于保存在执行时传递到回调的信息。The example defines a TaskInfo class to hold the information that is passed to the callback when it executes. 该示例创建一个 TaskInfo 对象,并为其分配一些字符串数据。The example creates a TaskInfo object and assigns it some string data. RegisterWaitForSingleObject 方法返回的 RegisteredWaitHandle 将分配给 TaskInfo 对象的 Handle 字段,以便回调方法有权访问该 RegisteredWaitHandleThe RegisteredWaitHandle that is returned by the RegisterWaitForSingleObject method is assigned to the Handle field of the TaskInfo object so that the callback method has access to the RegisteredWaitHandle.

除了将 TaskInfo 指定为要传递给回调方法的对象之外,对 RegisterWaitForSingleObject 方法的调用还指定任务将等待的 AutoResetEvent、表示 WaitProc 回调方法的 WaitOrTimerCallback 委托、一个秒的超时间隔和多个回调。In addition to specifying TaskInfo as the object to pass to the callback method, the call to the RegisterWaitForSingleObject method specifies the AutoResetEvent that the task will wait for, a WaitOrTimerCallback delegate that represents the WaitProc callback method, a one second time-out interval, and multiple callbacks.

当主线程通过调用其 Set 方法发出 AutoResetEvent 信号时,将调用 WaitOrTimerCallback 委托。When the main thread signals the AutoResetEvent by calling its Set method, the WaitOrTimerCallback delegate is invoked. WaitProc 方法测试 RegisteredWaitHandle 以确定是否发生了超时。The WaitProc method tests RegisteredWaitHandle to determine whether a time-out occurred. 如果回调是由于等待句柄已发出信号而调用的,则 WaitProc 方法会取消注册 RegisteredWaitHandle,从而停止其他回调。If the callback was invoked because the wait handle was signaled, the WaitProc method unregisters the RegisteredWaitHandle, stopping additional callbacks. 在超时情况下,任务将继续等待。In the case of a time-out, the task continues to wait. WaitProc 方法通过将消息打印到控制台来结束。The WaitProc method ends by printing a message to the console.

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。Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object.

(继承自 MarshalByRefObject)
Equals(Object)

确定指定的对象是否等于当前对象。Determines whether the specified object is equal to the current object.

(继承自 Object)
Finalize()

在垃圾回收将某一对象回收前允许该对象尝试释放资源并执行其他清理操作。Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.

GetHashCode()

用作默认哈希函数。Serves as the default hash function.

(继承自 Object)
GetLifetimeService()

检索控制此实例的生存期策略的当前生存期服务对象。Retrieves the current lifetime service object that controls the lifetime policy for this instance.

(继承自 MarshalByRefObject)
GetType()

获取当前实例的 TypeGets the Type of the current instance.

(继承自 Object)
InitializeLifetimeService()

获取生存期服务对象来控制此实例的生存期策略。Obtains a lifetime service object to control the lifetime policy for this instance.

(继承自 MarshalByRefObject)
MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(继承自 Object)
MemberwiseClone(Boolean)

创建当前 MarshalByRefObject 对象的浅表副本。Creates a shallow copy of the current MarshalByRefObject object.

(继承自 MarshalByRefObject)
ToString()

返回一个表示当前对象的 string。Returns a string that represents the current object.

(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。Cancels a registered wait operation issued by the RegisterWaitForSingleObject(WaitHandle, WaitOrTimerCallback, Object, UInt32, Boolean) method.

适用于

线程安全性

此类型是线程安全的。This type is thread safe.

另请参阅