TransactionScope.Dispose 方法
定义
结束事务范围。Ends the transaction scope.
public:
virtual void Dispose();
public void Dispose ();
abstract member Dispose : unit -> unit
override this.Dispose : unit -> unit
Public Sub Dispose ()
实现
示例
下面的示例演示如何使用 TransactionScope 类定义代码块以参与事务。The following example demonstrates how to use the TransactionScope class to define a block of code to participate in a transaction.
// 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
注解
调用此方法将标记事务范围的结尾。Calling this method marks the end of the transaction scope. 如果 TransactionScope 对象创建了事务并 Complete 在作用域上调用了,则在 TransactionScope 调用此方法时,该对象将尝试提交事务。If the TransactionScope object created the transaction and Complete was called on the scope, the TransactionScope object attempts to commit the transaction when this method is called. 在这种情况下,此方法将会阻止,直到完成事务处理的第一个阶段。In this case, this method blocks until the first phase of transaction processing is complete. 第一阶段在事务中的所有资源管理器和登记都已对事务结果进行了投票之后结束,并且 TransactionManager 已持久决定提交或中止事务。The first phase ends after all resource managers and enlistments in the transaction have voted on the transaction outcome and the TransactionManager has durably decided to commit or abort the transaction. 处理过程的第二个阶段始终是异步的。The second phase of processing is always asynchronous. 因此,无法保证刚从给定事务中提交的数据在不使用另一个事务查看此数据时立即可用。Therefore, there is no guarantee that data just committed from within a given transaction will be immediately available afterwards when not using another transaction to view this data.
使用 c # using 构造可确保即使发生异常,也会调用此方法。The use of the C# using construction ensures that this method is called even if an exception occurs. 在调用此方法之后所发生的异常不会影响事务。Exceptions that occur after calling this method may not affect the transaction. 此方法还会将环境事务还原到其原始状态。This method also restores the ambient transaction to it original state. TransactionAbortedException如果未实际提交事务,则会引发。A TransactionAbortedException is thrown if the transaction is not actually committed.
由于此方法在事务处理的第一阶段完成之前一直处于阻止状态,因此,在 Windows 窗体中使用此方法时, (WinForm) 应用程序或发生死锁时,应该非常小心。Because this method blocks until the first phase of transaction processing is complete, you should be extremely careful when using this method in a Windows Form (WinForm) application, or a deadlock can occur. 如果在一个 WinForm 控件事件中调用此方法 (例如,单击按钮) ,然后使用同步 Invoke 方法指示控件执行某些 UI 任务 (例如,在处理事务的过程中更改颜色) ,会发生死锁。If you call this method inside one WinForm Control event (for example, clicking a button), and use the synchronous Invoke method to direct the control to perform some UI tasks (for example, changing colors) in the middle of processing the transaction, a deadlock will happen. 这是因为 Invoke 方法是同步的,并会阻止工作线程,直到 UI 线程完成其作业为止。This is because the Invoke method is synchronous and blocks the worker thread until the UI thread finishes its job. 但是,在我们的方案中,UI 线程还会等待工作线程提交事务。However, in our scenario, the UI thread is also waiting for the worker thread to commit the transaction. 结果是,无可以继续,并且范围会无限期等待提交完成。The result is that none is able to proceed and the scope waits indefinitely for the Commit to finish. 你应 BeginInvoke 尽可能使用而不是 Invoke ,因为它是异步的,因此不容易出现死锁。You should use BeginInvoke rather than Invoke wherever possible, because it is asynchronous and thus less prone to deadlock.
有关如何使用此方法的详细信息,请参阅 使用事务范围实现隐式事务 主题。For more information on how this method is used, see the Implementing An Implicit Transaction Using Transaction Scope topic.