AsyncWaitHandle の使用によるアプリケーション実行のブロックBlocking Application Execution Using an AsyncWaitHandle

非同期操作の結果の待機中に、他の作業を継続できないアプリケーションは、操作が完了するまでブロックする必要があります。Applications that cannot continue to do other work while waiting for the results of an asynchronous operation must block until the operation completes. 次のオプションのいずれかを使用して、非同期操作が完了するまでの待機中に、アプリケーションのメイン スレッドをブロックします。Use one of the following options to block your application's main thread while waiting for an asynchronous operation to complete:

非同期操作が完了するまでブロックする 1 つ以上の WaitHandle オブジェクトを使用するアプリケーションは、通常は BeginOperationName メソッドを呼び出し、操作の結果なしで実行できるすべての作業を実行し、非同期操作が完了するまでブロックします。Applications that use one or more WaitHandle objects to block until an asynchronous operation is complete will typically call the BeginOperationName method, perform any work that can be done without the results of the operation, and then block until the asynchronous operation(s) completes. アプリケーションは、AsyncWaitHandle を使用して WaitOne メソッドのいずれかを呼び出し、単一の操作上でブロックできます。An application can block on a single operation by calling one of the WaitOne methods using the AsyncWaitHandle. 非同期操作のセットが完了するまで待機しながらブロックするには、関連する AsyncWaitHandle オブジェクトを配列に格納し、WaitAll メソッドのいずれかを呼び出します。To block while waiting for a set of asynchronous operations to complete, store the associated AsyncWaitHandle objects in an array and call one of the WaitAll methods. 非同期操作のいずれかのセットが完了するまで待機しながらブロックするには、関連する AsyncWaitHandle オブジェクトを配列に格納し、WaitAny メソッドのいずれかを呼び出します。To block while waiting for any one of a set of asynchronous operations to complete, store the associated AsyncWaitHandle objects in an array and call one of the WaitAny methods.

Example

次のコード例は、ユーザー指定のコンピューターのドメイン ネーム システム情報を取得するために、DNS クラスの非同期メソッドを使用してデモを実行します。The following code example demonstrates using asynchronous methods in the DNS class to retrieve Domain Name System information for a user-specified computer. 例では、非同期操作に関連付けられた WaitHandle を使用して、ブロックのデモを実行します。The example demonstrates blocking using the WaitHandle associated with the asynchronous operation. この方法を使用する場合は必要ないため、null (Visual Basic の場合は Nothing) は、BeginGetHostByNamerequestCallbackstateObject パラメーターに渡されることに注意してください。Note that null (Nothing in Visual Basic) is passed for the BeginGetHostByNamerequestCallback and stateObject parameters because these are not required when using this approach.

/*
The following example demonstrates using asynchronous methods to
get Domain Name System information for the specified host computer.

*/

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace Examples.AdvancedProgramming.AsynchronousOperations
{
    public class WaitUntilOperationCompletes
    {
        public static void Main(string[] args)
        {
            // Make sure the caller supplied a host name.
            if (args.Length == 0 || args[0].Length == 0)
            {
                // Print a message and exit.
                Console.WriteLine("You must specify the name of a host computer.");
                return;
            }
            // Start the asynchronous request for DNS information.
            IAsyncResult result = Dns.BeginGetHostEntry(args[0], null, null);
            Console.WriteLine("Processing request for information...");
            // Wait until the operation completes.
            result.AsyncWaitHandle.WaitOne();
            // The operation completed. Process the results.
            try 
            {
                // Get the results.
                IPHostEntry host = Dns.EndGetHostEntry(result);
                string[] aliases = host.Aliases;
                IPAddress[] addresses = host.AddressList;
                if (aliases.Length > 0)
                {
                    Console.WriteLine("Aliases");
                    for (int i = 0; i < aliases.Length; i++)
                    {
                        Console.WriteLine("{0}", aliases[i]);
                    }
                }
                if (addresses.Length > 0)
                {
                    Console.WriteLine("Addresses");
                    for (int i = 0; i < addresses.Length; i++)
                    {
                        Console.WriteLine("{0}",addresses[i].ToString());
                    }
                }
            }
            catch (SocketException e)
            {
                Console.WriteLine("Exception occurred while processing the request: {0}", 
                    e.Message);
            }
        }
    }
}
' The following example demonstrates using asynchronous methods to
' get Domain Name System information for the specified host computer.

Imports System.Net
Imports System.Net.Sockets
Imports System.Threading

namespace Examples.AdvancedProgramming.AsynchronousOperations
    Public Class WaitUntilOperationCompletes
    
        Public Shared Sub Main(args() as String)
            ' Make sure the caller supplied a host name.
            If(args.Length = 0)
                ' Print a message and exit.
                Console.WriteLine("You must specify the name of a host computer.")
                End
            End If
            ' Start the asynchronous request for DNS information.
            Dim result as IAsyncResult= Dns.BeginGetHostEntry(args(0), Nothing, Nothing)
            Console.WriteLine("Processing request for information...")
            ' Wait until the operation completes.
            result.AsyncWaitHandle.WaitOne()
            ' The operation completed. Process the results.
            Try 
                ' Get the results.
                Dim host as IPHostEntry = Dns.EndGetHostEntry(result)
                Dim  aliases() as String = host.Aliases
                Dim addresses() as IPAddress= host.AddressList
                Dim i as Integer
                If aliases.Length > 0
                    Console.WriteLine("Aliases")
                    For i = 0 To aliases.Length -1 
                        Console.WriteLine("{0}", aliases(i))
                    Next i
                End If
                If addresses.Length > 0
                    Console.WriteLine("Addresses")
                    For i = 0 To addresses.Length -1
                        Console.WriteLine("{0}", addresses(i).ToString())
                    Next i
                End If
            Catch e as SocketException
                  Console.WriteLine("An exception occurred while processing the request: {0}" _
                    , e.Message)
            End Try
        End Sub
    End Class
End Namespace

関連項目See also