IAsyncResult.AsyncWaitHandle IAsyncResult.AsyncWaitHandle IAsyncResult.AsyncWaitHandle IAsyncResult.AsyncWaitHandle Property

定義

非同期操作が完了するまで待機するために使用する WaitHandle を取得します。Gets a WaitHandle that is used to wait for an asynchronous operation to complete.

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

プロパティ値

非同期操作が完了するまで待機するために使用する WaitHandleA WaitHandle that is used to wait for an asynchronous operation to complete.

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と、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 that 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

戻り値を使用すると、クライアントは、操作が終了するまでポーリングIsCompletedするのではなく、非同期操作が完了するまで待機することができます。The return value allows the client to wait for an asynchronous operation to complete instead of polling IsCompleted until the operation concludes. 戻り値はWaitOne、、 WaitAny、のいずれかWaitAllの操作を実行するために使用できます。The return value can be used to perform a WaitOne, WaitAny, or WaitAll operation.

共通言語ランタイムはManualResetEvent、、 AutoResetEventMutexなど、複数の待機可能なオブジェクトを提供します。これらはすべて、Win32 同期プリミティブをミラー化します。The common language runtime supplies a number of waitable objects, such as ManualResetEvent, AutoResetEvent, and Mutex, all of which mirror Win32 synchronization primitives.

注意 (実装者)

を実装IAsyncResultするオブジェクトは、 AsyncWaitHandleプロパティが読み込まWaitHandleれるまでを作成する必要はありません。The object that implements IAsyncResult does not need to create the WaitHandle until the AsyncWaitHandle property is read. これは、 IAsyncResult実装者の選択です。It is the choice of the IAsyncResult implementer. ただし、実装者がをAsyncWaitHandle作成する場合は、適切なタイミングで待機をWaitHandle終了させるを通知するのは、実装側の責任です。However, if the implementer creates AsyncWaitHandle, it is the responsibility of the implementer to signal the WaitHandle that will terminate the wait at the appropriate time. たとえば、はAsyncResult 、非同期的に呼び出されたメソッドから制御が戻ったときに、呼び出し元に代わって待機を終了します。For example, AsyncResult terminates the wait on behalf of the caller when an asynchronously invoked method returns. 作成したAsyncWaitHandle後は、ユーザーが非同期操作を終了したメソッドを呼び出すまで、を維持したままにしておく必要があります。Once created, AsyncWaitHandle should be kept alive until the user calls the method that concludes the asynchronous operation. その時点で、背後AsyncWaitHandleにあるオブジェクトを破棄できます。At that time the object behind AsyncWaitHandle can be discarded.

注意 (呼び出し元)

(ポーリングではなく) 操作の完了を待機するクライアントは、このプロパティを使用して、待機する同期オブジェクトを取得します。Clients that wait for the operation to complete (as opposed to polling) use this property to obtain a synchronization object to wait on.

デリゲートのBeginInvokeメソッドを使用して非同期的にメソッドを呼び出し、その結果IAsyncResultから待機ハンドルを取得する場合、 Close()メソッドを呼び出すことにより、待機ハンドルの使用が終了したらすぐに待機ハンドルを閉じることをお勧めします。When you use the BeginInvoke method of a delegate to call a method asynchronously and obtain a wait handle from the resulting IAsyncResult, we recommend that you close the wait handle as soon as you are finished using it, by calling the Close() method. 待機ハンドルへのすべての参照を解放するだけの場合は、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が、破棄可能なオブジェクトが明示的に閉じられるか破棄されると、ガベージコレクションはより効率的に動作します。If you simply release all references to the wait handle, system resources are freed when garbage collection reclaims the wait handle, but garbage collection works more efficiently when disposable objects are explicitly closed or disposed. 詳細については、AsyncWaitHandle プロパティを参照してください。For more information, see the AsyncWaitHandle property.

適用対象