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これらのサンプルを使用するには、Microsoft.Data.SqlClient NuGet パッケージをインストールしてください。 Microsoft.Data.SqlClient は、非同期の接続文字列オプションを指定しなくても、ここに示されている BeginExecute と EndExecute のメソッドをサポートしています。
Asynchronous Processing=trueを追加しないでください。Microsoft.Data.SqlClient では、そのキーワードはサポートされていません。 新しいコードの場合は、ExecuteNonQueryAsyncとともにawaitおよびExecuteReaderAsyncを優先し、Task.WhenAnyまたはTask.WhenAllを使用して、要求スレッドをブロックせずに操作を調整します。
アプリケーションが一度に 1 つの非同期操作しか処理しない場合は、コールバック モデルとポーリング モデルが非同期操作の処理に役立ちます。 Wait モデルは、複数の非同期操作を処理するための、さらに柔軟な方法を提供します。 2 つの Wait モデルがあり、それを実装するために使用される WaitHandle メソッドから、Wait (Any) モデルと Wait (All) モデルという名前が付けられています。
どちらの Wait モデルを使用する場合でも、BeginExecuteNonQuery、BeginExecuteReader、または BeginExecuteXmlReader メソッドによって返される IAsyncResult オブジェクトの AsyncWaitHandle プロパティを使用してください。 WaitAnyオブジェクトの配列をWaitAllまたはWaitHandleに渡します。
どちらの Wait メソッドも、非同期操作を監視し、完了を待機します。 WaitAny メソッドは、いずれか 1 つの操作の完了またはタイムアウトを待機します。特定の操作が完了したことがわかれば、その結果を処理し、引き続き次の操作の完了またはタイムアウトを待機できます。WaitAll メソッドは、WaitHandle インスタンスの配列に含まれているすべてのプロセスが完了するかタイムアウトするまで次の操作の監視を開始しません。
Wait モデルの利点は、ある程度の長さの複数の操作を異なるサーバーで実行する必要がある場合や、サーバーがすべてのクエリを同時に処理するのに十分な性能を備えている場合に最も大きくなります。 ここで示す例では、重要度の低い SELECT クエリにさまざまな長さの WAITFOR コマンドを追加することによって、3 つのクエリが長いプロセスをエミュレートします。
例：「待機（任意）」モデル
次の例は Wait (Any) モデルを示しています。 3 つの非同期操作を開始した後、コードは WaitAny を呼び出して、いずれかの操作が完了するまで待機します。 完了した操作ごとに、コードは EndExecuteReader を呼び出し、結果の SqlDataReaderを読み取ります。 アプリケーションは、これらの結果を利用してページの一部を表示することができます。 代わりに、対応するテキスト ボックスに完了時間を追加します。 コードが操作を完了するたびに、その記録が保存されます。
完了したハンドルはシグナル状態のままであるため、この例では、保留中のリストから完了した各操作を削除してから、再度待機します。
この例を設定するには、新しい ASP.NET Web サイト プロジェクトを作成します。 ページ上に 1 つの Button コントロールと 4 つの TextBox コントロールを配置します (各コントロールの既定の名前をそのまま使用します)。
フォームのクラスに次のコードを追加してください。 2 つの Wait モデルの例では、GetConnectionString によって返される省略記号を、ご利用の接続文字列に置き換えてください。 Windows 統合認証を使用しているリモートサーバーの場合は、Server=<server>;Database=<database>;Integrated Security=true;Encrypt=true を使用します。
<server>と<database>をサーバー名とデータベース名に置き換え、クライアントが信頼するサーバー証明書を設定します。 その他の認証オプションについては、「接続文字列の構文」を参照してください。
' Add these to the top of the class
Imports System
Imports System.Collections.Generic
Imports System.Data
Imports Microsoft.Data.SqlClient
Imports System.Threading
' Add this code to the page's class:
Private Function GetConnectionString() As String
' To avoid storing the connection string in your code,
' you can retrieve it from a configuration file.
Return "..."
End Function
Sub Button1_Click( _
ByVal sender As Object, ByVal e As System.EventArgs)
' In a real-world application, you might be connecting to
' three different servers or databases. For the example,
' we connect to only one.
Dim connection1 As New SqlConnection(GetConnectionString())
Dim connection2 As New SqlConnection(GetConnectionString())
Dim connection3 As New SqlConnection(GetConnectionString())
' To keep the example simple, all three asynchronous
' processes select a row from the same table. WAITFOR
' commands are used to emulate long-running processes
' that complete after different periods of time.
Dim commandText1 As String = _
"WAITFOR DELAY '0:0:01';" & _
"SELECT * FROM Production.Product " & _
"WHERE ProductNumber = 'BL-2036'"
Dim commandText2 As String = _
"WAITFOR DELAY '0:0:05';" & _
"SELECT * FROM Production.Product " & _
"WHERE ProductNumber = 'BL-2036'"
Dim commandText3 As String = _
"WAITFOR DELAY '0:0:10';" & _
"SELECT * FROM Production.Product " & _
"WHERE ProductNumber = 'BL-2036'"
Dim waitHandles As New List(Of WaitHandle)
Dim pending As New List(Of Integer) From {0, 1, 2}
Try
' For each process, open a connection and begin execution.
' Use the IAsyncResult object returned by
' BeginExecuteReader to add a WaitHandle for the process
' to the pending list.
connection1.Open()
Dim command1 As New SqlCommand(commandText1, connection1)
Dim result1 As IAsyncResult = _
command1.BeginExecuteReader()
waitHandles.Add(result1.AsyncWaitHandle)
connection2.Open()
Dim command2 As New SqlCommand(commandText2, connection2)
Dim result2 As IAsyncResult = _
command2.BeginExecuteReader()
waitHandles.Add(result2.AsyncWaitHandle)
connection3.Open()
Dim command3 As New SqlCommand(commandText3, connection3)
Dim result3 As IAsyncResult = _
command3.BeginExecuteReader()
waitHandles.Add(result3.AsyncWaitHandle)
Dim index As Integer
For countWaits As Integer = 1 To 3
' WaitAny waits for any of the processes to complete.
' The return value is either the index of the
' array element whose process just completed, or
' the WaitTimeout value.
index = WaitHandle.WaitAny(waitHandles.ToArray(), 60000, False)
If index = WaitHandle.WaitTimeout Then
Throw New Exception("Timeout")
End If
' This example doesn't actually do anything with the
' data returned by the processes, but the code opens
' readers for each just to demonstrate the concept.
' Instead of using the returned data to fill the
' controls on the page, the example adds the time
' the process was completed to the corresponding
' text box.
Select Case pending(index)
Case 0
Dim reader1 As SqlDataReader
reader1 = command1.EndExecuteReader(result1)
If reader1.Read Then
TextBox1.Text = _
"Completed " & _
System.DateTime.Now.ToLongTimeString()
End If
reader1.Close()
Case 1
Dim reader2 As SqlDataReader
reader2 = command2.EndExecuteReader(result2)
If reader2.Read Then
TextBox2.Text = _
"Completed " & _
System.DateTime.Now.ToLongTimeString()
End If
reader2.Close()
Case 2
Dim reader3 As SqlDataReader
reader3 = command3.EndExecuteReader(result3)
If reader3.Read Then
TextBox3.Text = _
"Completed " & _
System.DateTime.Now.ToLongTimeString()
End If
reader3.Close()
End Select
waitHandles.RemoveAt(index)
pending.RemoveAt(index)
Next
Catch ex As Exception
TextBox4.Text = ex.ToString
End Try
connection1.Close()
connection2.Close()
connection3.Close()
End Sub
// Add the following using directives, if they aren't already there.
using System;
using System.Collections.Generic;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Threading;
using Microsoft.Data.SqlClient;
// Add this code to the page's class
string GetConnectionString()
// To avoid storing the connection string in your code,
// you can retrieve it from a configuration file.
{
return "...";
}
void Button1_Click(object sender, System.EventArgs e)
{
// In a real-world application, you might be connecting to
// three different servers or databases. For the example,
// we connect to only one.
SqlConnection connection1 =
new SqlConnection(GetConnectionString());
SqlConnection connection2 =
new SqlConnection(GetConnectionString());
SqlConnection connection3 =
new SqlConnection(GetConnectionString());
// To keep the example simple, all three asynchronous
// processes select a row from the same table. WAITFOR
// commands are used to emulate long-running processes
// that complete after different periods of time.
string commandText1 = "WAITFOR DELAY '0:0:01';" +
"SELECT * FROM Production.Product " +
"WHERE ProductNumber = 'BL-2036'";
string commandText2 = "WAITFOR DELAY '0:0:05';" +
"SELECT * FROM Production.Product " +
"WHERE ProductNumber = 'BL-2036'";
string commandText3 = "WAITFOR DELAY '0:0:10';" +
"SELECT * FROM Production.Product " +
"WHERE ProductNumber = 'BL-2036'";
try
// For each process, open a connection and begin
// execution. Use the IAsyncResult object returned by
// BeginExecuteReader to add a WaitHandle for the
// process to the pending list.
{
connection1.Open();
SqlCommand command1 =
new SqlCommand(commandText1, connection1);
IAsyncResult result1 = command1.BeginExecuteReader();
WaitHandle waitHandle1 = result1.AsyncWaitHandle;
connection2.Open();
SqlCommand command2 =
new SqlCommand(commandText2, connection2);
IAsyncResult result2 = command2.BeginExecuteReader();
WaitHandle waitHandle2 = result2.AsyncWaitHandle;
connection3.Open();
SqlCommand command3 =
new SqlCommand(commandText3, connection3);
IAsyncResult result3 = command3.BeginExecuteReader();
WaitHandle waitHandle3 = result3.AsyncWaitHandle;
List<WaitHandle> waitHandles = new List<WaitHandle> {
waitHandle1, waitHandle2, waitHandle3
};
List<int> pending = new List<int> { 0, 1, 2 };
int index;
for (int countWaits = 0; countWaits <= 2; countWaits++)
{
// WaitAny waits for any of the processes to
// complete. The return value is either the index
// of the array element whose process just
// completed, or the WaitTimeout value.
index = WaitHandle.WaitAny(waitHandles.ToArray(),
60000, false);
if (index == WaitHandle.WaitTimeout)
{
throw new Exception("Timeout");
}
// This example doesn't actually do anything with
// the data returned by the processes, but the
// code opens readers for each just to demonstrate
// the concept.
// Instead of using the returned data to fill the
// controls on the page, the example adds the time
// the process was completed to the corresponding
// text box.
switch (pending[index])
{
case 0:
SqlDataReader reader1;
reader1 =
command1.EndExecuteReader(result1);
if (reader1.Read())
{
TextBox1.Text =
"Completed " +
System.DateTime.Now.ToLongTimeString();
}
reader1.Close();
break;
case 1:
SqlDataReader reader2;
reader2 =
command2.EndExecuteReader(result2);
if (reader2.Read())
{
TextBox2.Text =
"Completed " +
System.DateTime.Now.ToLongTimeString();
}
reader2.Close();
break;
case 2:
SqlDataReader reader3;
reader3 =
command3.EndExecuteReader(result3);
if (reader3.Read())
{
TextBox3.Text =
"Completed " +
System.DateTime.Now.ToLongTimeString();
}
reader3.Close();
break;
}
waitHandles.RemoveAt(index);
pending.RemoveAt(index);
}
}
catch (Exception ex)
{
TextBox4.Text = ex.ToString();
}
connection1.Close();
connection2.Close();
connection3.Close();
}
例:Wait (All) モデル
次の例は Wait (All) モデルを示しています。 3 つの非同期プロセスが開始されると、プロセスの完了またはタイムアウトを待つ WaitAll メソッドが呼び出されます。
Wait (Any) モデルの例と同様に、プロセスが完了した時刻が、そのプロセスに対応するテキスト ボックスに追加されます。 ここでも、テキスト ボックス内の時刻がその時点を示します。WaitAny メソッドに続くコードは、すべてのプロセスが完了した後でのみ実行されます。
この例を設定するには、新しい ASP.NET Web サイト プロジェクトを作成します。 ページ上に 1 つの Button コントロールと 4 つの TextBox コントロールを配置します (各コントロールの既定の名前をそのまま使用します)。
お使いの環境に応じて接続文字列を変更し、次のコードをフォームのクラスに追加します。
' Add these to the top of the class
Imports System
Imports System.Data
Imports Microsoft.Data.SqlClient
Imports System.Threading
' Add this code to the page's class:
Private Function GetConnectionString() As String
' To avoid storing the connection string in your code,
' you can retrieve it from a configuration file.
Return "..."
End Function
Sub Button1_Click( _
ByVal sender As Object, ByVal e As System.EventArgs)
' In a real-world application, you might be connecting to
' three different servers or databases. For the example,
' we connect to only one.
Dim connection1 As New SqlConnection(GetConnectionString())
Dim connection2 As New SqlConnection(GetConnectionString())
Dim connection3 As New SqlConnection(GetConnectionString())
' To keep the example simple, all three asynchronous
' processes select a row from the same table. WAITFOR
' commands are used to emulate long-running processes
' that complete after different periods of time.
Dim commandText1 As String = _
"UPDATE Production.Product " & _
"SET ReorderPoint = ReorderPoint + 1 " & _
"WHERE ReorderPoint Is Not Null;" & _
"WAITFOR DELAY '0:0:01';" & _
"UPDATE Production.Product " & _
"SET ReorderPoint = ReorderPoint - 1 " & _
"WHERE ReorderPoint Is Not Null"
Dim commandText2 As String = _
"UPDATE Production.Product " & _
"SET ReorderPoint = ReorderPoint + 1 " & _
"WHERE ReorderPoint Is Not Null;" & _
"WAITFOR DELAY '0:0:05';" & _
"UPDATE Production.Product " & _
"SET ReorderPoint = ReorderPoint - 1 " & _
"WHERE ReorderPoint Is Not Null"
Dim commandText3 As String = _
"UPDATE Production.Product " & _
"SET ReorderPoint = ReorderPoint + 1 " & _
"WHERE ReorderPoint Is Not Null;" & _
"WAITFOR DELAY '0:0:10';" & _
"UPDATE Production.Product " & _
"SET ReorderPoint = ReorderPoint - 1 " & _
"WHERE ReorderPoint Is Not Null"
Dim waitHandles(2) As WaitHandle
Try
' For each process, open a connection and begin execution.
' Use the IAsyncResult object returned by
' BeginExecuteReader to add a WaitHandle for the process
' to the array.
connection1.Open()
Dim command1 As New SqlCommand(commandText1, connection1)
Dim result1 As IAsyncResult = _
command1.BeginExecuteNonQuery()
waitHandles(0) = result1.AsyncWaitHandle
connection2.Open()
Dim command2 As New SqlCommand(commandText2, connection2)
Dim result2 As IAsyncResult = _
command2.BeginExecuteNonQuery()
waitHandles(1) = result2.AsyncWaitHandle
connection3.Open()
Dim command3 As New SqlCommand(commandText3, connection3)
Dim result3 As IAsyncResult = _
command3.BeginExecuteNonQuery()
waitHandles(2) = result3.AsyncWaitHandle
' WaitAll waits for all of the processes to complete.
' The return value is True if all processes completed,
' False if any process timed out.
Dim result As Boolean = _
WaitHandle.WaitAll(waitHandles, 60000, False)
If result Then
Dim rowCount1 As Long = _
command1.EndExecuteNonQuery(result1)
TextBox1.Text = _
"Completed " & _
System.DateTime.Now.ToLongTimeString()
Dim rowCount2 As Long = _
command2.EndExecuteNonQuery(result2)
TextBox2.Text = _
"Completed " & _
System.DateTime.Now.ToLongTimeString()
Dim rowCount3 As Long = _
command3.EndExecuteNonQuery(result3)
TextBox3.Text = _
"Completed " & _
System.DateTime.Now.ToLongTimeString()
Else
Throw New Exception("Timeout")
End If
Catch ex As Exception
TextBox4.Text = ex.ToString
End Try
connection1.Close()
connection2.Close()
connection3.Close()
End Sub
// Add the following using directives, if they aren't already there.
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Threading;
using Microsoft.Data.SqlClient;
// Add this code to the page's class
string GetConnectionString()
// To avoid storing the connection string in your code,
// you can retrieve it from a configuration file.
{
return "...";
}
void Button1_Click(object sender, System.EventArgs e)
{
// In a real-world application, you might be connecting to
// three different servers or databases. For the example,
// we connect to only one.
SqlConnection connection1 =
new SqlConnection(GetConnectionString());
SqlConnection connection2 =
new SqlConnection(GetConnectionString());
SqlConnection connection3 =
new SqlConnection(GetConnectionString());
// To keep the example simple, all three asynchronous
// processes execute UPDATE queries that result in
// no change to the data. WAITFOR
// commands are used to emulate long-running processes
// that complete after different periods of time.
string commandText1 =
"UPDATE Production.Product " +
"SET ReorderPoint = ReorderPoint + 1 " +
"WHERE ReorderPoint Is Not Null;" +
"WAITFOR DELAY '0:0:01';" +
"UPDATE Production.Product " +
"SET ReorderPoint = ReorderPoint - 1 " +
"WHERE ReorderPoint Is Not Null";
string commandText2 =
"UPDATE Production.Product " +
"SET ReorderPoint = ReorderPoint + 1 " +
"WHERE ReorderPoint Is Not Null;" +
"WAITFOR DELAY '0:0:05';" +
"UPDATE Production.Product " +
"SET ReorderPoint = ReorderPoint - 1 " +
"WHERE ReorderPoint Is Not Null";
string commandText3 =
"UPDATE Production.Product " +
"SET ReorderPoint = ReorderPoint + 1 " +
"WHERE ReorderPoint Is Not Null;" +
"WAITFOR DELAY '0:0:10';" +
"UPDATE Production.Product " +
"SET ReorderPoint = ReorderPoint - 1 " +
"WHERE ReorderPoint Is Not Null";
try
// For each process, open a connection and begin
// execution. Use the IAsyncResult object returned by
// BeginExecuteReader to add a WaitHandle for the
// process to the array.
{
connection1.Open();
SqlCommand command1 =
new SqlCommand(commandText1, connection1);
IAsyncResult result1 = command1.BeginExecuteNonQuery();
WaitHandle waitHandle1 = result1.AsyncWaitHandle;
connection2.Open();
SqlCommand command2 =
new SqlCommand(commandText2, connection2);
IAsyncResult result2 = command2.BeginExecuteNonQuery();
WaitHandle waitHandle2 = result2.AsyncWaitHandle;
connection3.Open();
SqlCommand command3 =
new SqlCommand(commandText3, connection3);
IAsyncResult result3 = command3.BeginExecuteNonQuery();
WaitHandle waitHandle3 = result3.AsyncWaitHandle;
WaitHandle[] waitHandles = {
waitHandle1, waitHandle2, waitHandle3
};
bool result;
// WaitAll waits for all of the processes to
// complete. The return value is True if the processes
// all completed successfully, False if any process
// timed out.
result = WaitHandle.WaitAll(waitHandles, 60000, false);
if(result)
{
long rowCount1 =
command1.EndExecuteNonQuery(result1);
TextBox1.Text = "Completed " +
System.DateTime.Now.ToLongTimeString();
long rowCount2 =
command2.EndExecuteNonQuery(result2);
TextBox2.Text = "Completed " +
System.DateTime.Now.ToLongTimeString();
long rowCount3 =
command3.EndExecuteNonQuery(result3);
TextBox3.Text = "Completed " +
System.DateTime.Now.ToLongTimeString();
}
else
{
throw new Exception("Timeout");
}
}
catch (Exception ex)
{
TextBox4.Text = ex.ToString();
}
connection1.Close();
connection2.Close();
connection3.Close();
}
