TransactionScope.Dispose Metode

Definisi

Ruang nama:

System.Transactions

Rakitan:

System.Transactions.Local.dll

Sumber:

TransactionScope.cs

Mengakhiri cakupan transaksi.

public:
 virtual void Dispose();

public void Dispose ();

abstract member Dispose : unit -> unit
override this.Dispose : unit -> unit

Public Sub Dispose ()

Penerapan

Dispose()

Contoh

Contoh berikut menunjukkan cara menggunakan TransactionScope kelas untuk menentukan blok kode untuk berpartisipasi dalam transaksi.

// This function takes arguments for 2 connection strings and commands to create a transaction 
// involving two SQL Servers. It returns a value > 0 if the transaction is committed, 0 if the 
// transaction is rolled back. To test this code, you can connect to two different databases 
// on the same server by altering the connection string, or to another 3rd party RDBMS by 
// altering the code in the connection2 code block.
static public int CreateTransactionScope(
    string connectString1, string connectString2,
    string commandText1, string commandText2)
{
    // Initialize the return value to zero and create a StringWriter to display results.
    int returnValue = 0;
    System.IO.StringWriter writer = new System.IO.StringWriter();

    try
    {
        // Create the TransactionScope to execute the commands, guaranteeing
        // that both commands can commit or roll back as a single unit of work.
        using (TransactionScope scope = new TransactionScope())
        {
            using (SqlConnection connection1 = new SqlConnection(connectString1))
            {
                // Opening the connection automatically enlists it in the 
                // TransactionScope as a lightweight transaction.
                connection1.Open();

                // Create the SqlCommand object and execute the first command.
                SqlCommand command1 = new SqlCommand(commandText1, connection1);
                returnValue = command1.ExecuteNonQuery();
                writer.WriteLine("Rows to be affected by command1: {0}", returnValue);

                // If you get here, this means that command1 succeeded. By nesting
                // the using block for connection2 inside that of connection1, you
                // conserve server and network resources as connection2 is opened
                // only when there is a chance that the transaction can commit.   
                using (SqlConnection connection2 = new SqlConnection(connectString2))
                {
                    // The transaction is escalated to a full distributed
                    // transaction when connection2 is opened.
                    connection2.Open();

                    // Execute the second command in the second database.
                    returnValue = 0;
                    SqlCommand command2 = new SqlCommand(commandText2, connection2);
                    returnValue = command2.ExecuteNonQuery();
                    writer.WriteLine("Rows to be affected by command2: {0}", returnValue);
                }
            }

            // The Complete method commits the transaction. If an exception has been thrown,
            // Complete is not  called and the transaction is rolled back.
            scope.Complete();
        }
    }
    catch (TransactionAbortedException ex)
    {
        writer.WriteLine("TransactionAbortedException Message: {0}", ex.Message);
    }

    // Display messages.
    Console.WriteLine(writer.ToString());

    return returnValue;
}

'  This function takes arguments for 2 connection strings and commands to create a transaction 
'  involving two SQL Servers. It returns a value > 0 if the transaction is committed, 0 if the 
'  transaction is rolled back. To test this code, you can connect to two different databases 
'  on the same server by altering the connection string, or to another 3rd party RDBMS  
'  by altering the code in the connection2 code block.
Public Function CreateTransactionScope( _
  ByVal connectString1 As String, ByVal connectString2 As String, _
  ByVal commandText1 As String, ByVal commandText2 As String) As Integer

    ' Initialize the return value to zero and create a StringWriter to display results.
    Dim returnValue As Integer = 0
    Dim writer As System.IO.StringWriter = New System.IO.StringWriter

    Try
    ' Create the TransactionScope to execute the commands, guaranteeing
    '  that both commands can commit or roll back as a single unit of work.
        Using scope As New TransactionScope()
            Using connection1 As New SqlConnection(connectString1)
                ' Opening the connection automatically enlists it in the 
                ' TransactionScope as a lightweight transaction.
                connection1.Open()

                ' Create the SqlCommand object and execute the first command.
                Dim command1 As SqlCommand = New SqlCommand(commandText1, connection1)
                returnValue = command1.ExecuteNonQuery()
                writer.WriteLine("Rows to be affected by command1: {0}", returnValue)

                ' If you get here, this means that command1 succeeded. By nesting
                ' the using block for connection2 inside that of connection1, you
                ' conserve server and network resources as connection2 is opened
                ' only when there is a chance that the transaction can commit.   
                Using connection2 As New SqlConnection(connectString2)
                    ' The transaction is escalated to a full distributed
                    ' transaction when connection2 is opened.
                    connection2.Open()

                    ' Execute the second command in the second database.
                    returnValue = 0
                    Dim command2 As SqlCommand = New SqlCommand(commandText2, connection2)
                    returnValue = command2.ExecuteNonQuery()
                    writer.WriteLine("Rows to be affected by command2: {0}", returnValue)
                End Using
            End Using

        ' The Complete method commits the transaction. If an exception has been thrown,
        ' Complete is called and the transaction is rolled back.
        scope.Complete()
        End Using
    Catch ex As TransactionAbortedException
        writer.WriteLine("TransactionAbortedException Message: {0}", ex.Message)
    End Try

    ' Display messages.
    Console.WriteLine(writer.ToString())

    Return returnValue
End Function

Keterangan

Memanggil metode ini menandai akhir cakupan transaksi. TransactionScope Jika objek membuat transaksi dan Complete dipanggil pada cakupan, TransactionScope objek mencoba untuk melakukan transaksi ketika metode ini dipanggil. Dalam hal ini, metode ini memblokir hingga fase pertama pemrosesan transaksi selesai. Fase pertama berakhir setelah semua manajer sumber daya dan pendaftaran dalam transaksi telah memilih hasil transaksi dan TransactionManager telah memutuskan untuk menerapkan atau membatalkan transaksi. Fase kedua pemrosesan selalu asinkron. Oleh karena itu, tidak ada jaminan bahwa data yang baru saja dilakukan dari dalam transaksi tertentu akan segera tersedia setelahnya ketika tidak menggunakan transaksi lain untuk melihat data ini.

Penggunaan konstruksi C# using memastikan bahwa metode ini dipanggil bahkan jika pengecualian terjadi. Pengecualian yang terjadi setelah memanggil metode ini mungkin tidak mempengaruhi transaksi. Metode ini juga memulihkan transaksi sekitar ke status aslinya. dilemparkan TransactionAbortedException jika transaksi tidak benar-benar dilakukan.

Karena metode ini memblokir hingga fase pertama pemrosesan transaksi selesai, Anda harus sangat berhati-hati saat menggunakan metode ini dalam aplikasi Windows Form (WinForm), atau kebuntuan dapat terjadi. Jika Anda memanggil metode ini di dalam satu peristiwa Kontrol WinForm (misalnya, mengklik tombol), dan menggunakan metode sinkron Invoke untuk mengarahkan kontrol untuk melakukan beberapa tugas UI (misalnya, mengubah warna) di tengah pemrosesan transaksi, kebuntuan akan terjadi. Ini karena Invoke metode ini sinkron dan memblokir utas pekerja sampai utas UI menyelesaikan pekerjaannya. Namun, dalam skenario kami, utas UI juga menunggu utas pekerja melakukan transaksi. Hasilnya adalah bahwa tidak ada yang dapat melanjutkan dan cakupan menunggu tanpa batas waktu agar Penerapan selesai. Anda harus menggunakan BeginInvoke daripada Invoke sedapat mungkin, karena itu asinkron dan dengan demikian kurang rentan terhadap kebuntuan.

Untuk informasi selengkapnya tentang bagaimana metode ini digunakan, lihat topik Menerapkan Transaksi Implisit Menggunakan Cakupan Transaksi .

Lihat juga

• Menerapkan transaksi implisit menggunakan cakupan transaksi