AsyncResult.AsyncWaitHandle AsyncResult.AsyncWaitHandle AsyncResult.AsyncWaitHandle AsyncResult.AsyncWaitHandle Property

定義

Win32 同期ハンドルをカプセル化し、各種の同期スキームを実装できるようにする WaitHandle を取得します。Gets a WaitHandle that encapsulates Win32 synchronization handles, and allows the implementation of various synchronization schemes.

public:
 virtual property System::Threading::WaitHandle ^ AsyncWaitHandle { System::Threading::WaitHandle ^ get(); };
public virtual System.Threading.WaitHandle AsyncWaitHandle { get; }
member this.AsyncWaitHandle : System.Threading.WaitHandle
Public Overridable ReadOnly Property AsyncWaitHandle As WaitHandle

プロパティ値

Win32 同期ハンドルをカプセル化し、各種の同期スキームを実装できるようにする WaitHandleA WaitHandle that encapsulates Win32 synchronization handles, and allows the implementation of various synchronization schemes.

実装

次の例は、 AsyncWaitHandleプロパティを使用してをWaitHandle取得する方法と、デリゲートに対する非同期呼び出しを待機する方法を示しています。The following example demonstrates how to use the AsyncWaitHandle property to get a WaitHandle, and how to wait for an asynchronous call on a delegate. WaitHandle は非同期呼び出しが完了すると通知され、 WaitOne メソッドを呼び出すことによってこれを待機できます。The WaitHandle is signaled when the asynchronous call completes, and you can wait for it by calling the WaitOne method.

この例は、2つのクラス、非同期に呼び出されるメソッドを含むクラス、および呼び出しを行うMainメソッドを含むクラスで構成されています。The example consists of two classes, the class that contains the method which is called asynchronously, and the class that contains the Main method that makes the call.

デリゲートを使用した非同期メソッドの呼び出しの詳細と例については、「同期メソッドの非同期呼び出し」を参照してください。For more information and more examples of calling methods asynchronously by using delegates, see Calling Synchronous Methods Asynchronously.

using namespace System;
using namespace System::Threading;
using namespace System::Runtime::InteropServices; 

namespace Examples {
namespace AdvancedProgramming {
namespace AsynchronousOperations
{
    public ref class AsyncDemo 
    {
    public:
        // The method to be executed asynchronously.
        String^ TestMethod(int callDuration, [OutAttribute] int% threadId) 
        {
            Console::WriteLine("Test method begins.");
            Thread::Sleep(callDuration);
            threadId = Thread::CurrentThread->ManagedThreadId;
            return String::Format("My call time was {0}.", callDuration);
        }
    };

    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate String^ AsyncMethodCaller(int callDuration, [OutAttribute] int% threadId);
}}}
using System;
using System.Threading; 

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncDemo 
    {
        // The method to be executed asynchronously.
        public string TestMethod(int callDuration, out int threadId) 
        {
            Console.WriteLine("Test method begins.");
            Thread.Sleep(callDuration);
            threadId = Thread.CurrentThread.ManagedThreadId;
            return String.Format("My call time was {0}.", callDuration.ToString());
        }
    }
    // The delegate must have the same signature as the method
    // it will call asynchronously.
    public delegate string AsyncMethodCaller(int callDuration, out int threadId);
}
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations
    Public Class AsyncDemo 
        ' The method to be executed asynchronously.
        Public Function TestMethod(ByVal callDuration As Integer, _
                <Out> ByRef threadId As Integer) As String
            Console.WriteLine("Test method begins.")
            Thread.Sleep(callDuration)
            threadId = Thread.CurrentThread.ManagedThreadId()
            return String.Format("My call time was {0}.", callDuration.ToString())
        End Function
    End Class

    ' The delegate must have the same signature as the method
    ' it will call asynchronously.
    Public Delegate Function AsyncMethodCaller(ByVal callDuration As Integer, _
        <Out> ByRef threadId As Integer) As String
End Namespace
#using <TestMethod.dll>

using namespace System;
using namespace System::Threading;
using namespace Examples::AdvancedProgramming::AsynchronousOperations;

void main() 
{
    // The asynchronous method puts the thread id here.
    int threadId;

    // Create an instance of the test class.
    AsyncDemo^ ad = gcnew AsyncDemo();

    // Create the delegate.
    AsyncMethodCaller^ caller = gcnew AsyncMethodCaller(ad, &AsyncDemo::TestMethod);
       
    // Initiate the asychronous call.
    IAsyncResult^ result = caller->BeginInvoke(3000, 
        threadId, nullptr, nullptr);

    Thread::Sleep(0);
    Console::WriteLine("Main thread {0} does some work.",
        Thread::CurrentThread->ManagedThreadId);

    // Wait for the WaitHandle to become signaled.
    result->AsyncWaitHandle->WaitOne();

    // Perform additional processing here.
    // Call EndInvoke to retrieve the results.
    String^ returnValue = caller->EndInvoke(threadId, result);

    // Close the wait handle.
    result->AsyncWaitHandle->Close();

    Console::WriteLine("The call executed on thread {0}, with return value \"{1}\".",
        threadId, returnValue);
}

/* This example produces output similar to the following:

Main thread 1 does some work.
Test method begins.
The call executed on thread 3, with return value "My call time was 3000.".
 */
using System;
using System.Threading;

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class AsyncMain 
    {
        static void Main() 
        {
            // The asynchronous method puts the thread id here.
            int threadId;

            // Create an instance of the test class.
            AsyncDemo ad = new AsyncDemo();

            // Create the delegate.
            AsyncMethodCaller caller = new AsyncMethodCaller(ad.TestMethod);
       
            // Initiate the asychronous call.
            IAsyncResult result = caller.BeginInvoke(3000, 
                out threadId, null, null);

            Thread.Sleep(0);
            Console.WriteLine("Main thread {0} does some work.",
                Thread.CurrentThread.ManagedThreadId);

            // Wait for the WaitHandle to become signaled.
            result.AsyncWaitHandle.WaitOne();

            // Perform additional processing here.
            // Call EndInvoke to retrieve the results.
            string returnValue = caller.EndInvoke(out threadId, result);

            // Close the wait handle.
            result.AsyncWaitHandle.Close();

            Console.WriteLine("The call executed on thread {0}, with return value \"{1}\".",
                threadId, returnValue);
        }
    }
}

/* This example produces output similar to the following:

Main thread 1 does some work.
Test method begins.
The call executed on thread 3, with return value "My call time was 3000.".
 */
Imports System.Threading
Imports System.Runtime.InteropServices 

Namespace Examples.AdvancedProgramming.AsynchronousOperations

    Public Class AsyncMain 
        Shared Sub Main() 
            ' The asynchronous method puts the thread id here.
            Dim threadId As Integer

            ' Create an instance of the test class.
            Dim ad As New AsyncDemo()

            ' Create the delegate.
            Dim caller As New AsyncMethodCaller(AddressOf ad.TestMethod)
       
            ' Initiate the asynchronous call.
            Dim result As IAsyncResult = caller.BeginInvoke(3000, _
                threadId, Nothing, Nothing)

            Thread.Sleep(0)
            Console.WriteLine("Main thread {0} does some work.", _
                Thread.CurrentThread.ManagedThreadId)
            ' Perform additional processing here and then
            ' wait for the WaitHandle to be signaled.
            result.AsyncWaitHandle.WaitOne()

            ' Call EndInvoke to retrieve the results.
            Dim returnValue As String = caller.EndInvoke(threadId, result)

            ' Close the wait handle.
            result.AsyncWaitHandle.Close()

            Console.WriteLine("The call executed on thread {0}, with return value ""{1}"".", _
                threadId, returnValue)
        End Sub
    End Class
End Namespace

'This example produces output similar to the following:
'
'Main thread 1 does some work.
'Test method begins.
'The call executed on thread 3, with return value "My call time was 3000.".

注釈

非同期WaitHandle操作が完了すると、このメソッドによって返されたが自動的に通知されます。The WaitHandle returned by this method is automatically signaled when the asynchronous operation has completed.

非同期メソッド呼び出しを行うために使用されEndInvokeたデリゲートでを呼び出すと、待機ハンドルは自動的に閉じられません。The wait handle is not closed automatically when you call EndInvoke on the delegate that was used to make the asynchronous method call. 待機ハンドルへのすべての参照を解放すると、ガベージ コレクションが待機ハンドルをクリアするときにシステム リソースが解放されます。If you release all references to the wait handle, system resources are freed when garbage collection reclaims the wait handle. 待機ハンドルの使用が終了したらすぐにシステムリソースを解放するには、 WaitHandle.Closeメソッドを呼び出します。To free the system resources as soon as you are finished using the wait handle, call the WaitHandle.Close method. 破棄可能なオブジェクトが明示的に終了または破棄されると、ガベージコレクションはより効率的に動作します。Garbage collection works more efficiently when disposable objects are explicitly closed or disposed.

注意事項

プロパティに格納されているは、 WaitHandle非同期呼び出しが完了するまで現在のスレッドをブロックするために使用できます。 AsyncWaitHandleThe WaitHandle contained in the AsyncWaitHandle property can be used to block the current thread until the asynchronous call is complete. ただし、 BeginInvoke呼び出し中にAsyncCallbackが指定されている場合、はを無視します。 WaitHandleHowever the WaitHandle will ignore the AsyncCallback, if one was specified during the BeginInvoke call. したがって、非同期呼び出しが完了するまでブロックするためにAsyncCallbackWaitHandle使用している場合でも、の実行が完了する前にアプリケーションがシャットダウンされる状況が発生する可能性があります。Therefore, a situation can occur where the application shuts down before the AsyncCallback has finished executing, even if a WaitHandle is used to block until the asynchronous call completion. このような状況の例については、 AsyncResultクラスの例を参照し、 Thread.Sleepステートメントを削除してください。For an example of such a situation, see the example for the AsyncResult class, and remove the Thread.Sleep statement.

適用対象

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