瞭解如何transaction.complete功能？

Question

嗨我們已經開始使用事務範圍，下面是代碼片段。我們需要了解的是，基於我們在每次使用連接之後的特定連接將被處理/關閉的內容，因此，自從關閉transaction.complete以後如何工作？

using (TransactionScope transScope = new TransactionScope()) 
{ 
    try 
    { 
     string myConnStringLocal = "User Id=***;Password=****;Host=" + globalSettings.settingLocalIP + ";Database=" + globalSettings.settingLocalDB; 
     using (MySqlConnection connectionLocal = new MySqlConnection(myConnStringLocal)) 
     { 
     try{ 
     connectionLocal.Open(); 
     } 
     Catch(Exception e) 
     { 

     } 
     finally{ 
     connectionLocal.Close(); 
     } 
     } 

     string myConnStringCentral = "User Id=***;Password=*****;Host=" + globalSettings.settingCentralIP + ";Database=" + globalSettings.settingCentralDB; 
     using (MySqlConnection connectionCentral = new MySqlConnection(myConnStringCentral)) 
     { 
     try{ 
     connectionCentral.Open(); 
     } 
     Catch(Exception e) 
     { 

     } 
     finally{ 
     connectionCentral.Close(); 
     } 

     } 
     string myConnStringCentralCopy = "User Id=*****;Password=*****;Host=" + globalSettings.settingCentralCopyIP + ";Database=" + globalSettings.settingCentralCopyDB; 
     using (MySqlConnection connectionCentralCopy = new MySqlConnection(myConnStringCentralCopy)) 
     { 
     try{ 
     connectionCentralCopy.Open(); 
     } 
     Catch(Exception e) 
     { 

     } 
     finally{ 
     connectionCentralCopy.Close(); 
     } 
     } 
     transScope.Complete(); 
     Console.WriteLine("Transaction is completed"); 
    } 
    catch (Exception) 
    { 
     Console.WriteLine("Transaction is rolled back"); 
    } 
} 

Answer 1

TransactionScope.Complete告訴所有的交易經理他們很好提交此交易。這不是一切都會實際承諾的保證。在完成方法被調用後，所有事務管理器都會單獨啓動一次提交，並且如果所有事務管理器都成功，則事務被視爲已成功完成。 你可以參考這個link for further details

Answer 2

using (TransactionScope transScope = new TransactionScope()) 
    { 
     try 
     { 
      string myConnStringLocal = "User Id=***;Password=****;Host=" + globalSettings.settingLocalIP + ";Database=" + globalSettings.settingLocalDB; 
      using (MySqlConnection connectionLocal = new MySqlConnection(myConnStringLocal)) 
      { 
       connectionLocal.Open(); 
      } 

      string myConnStringCentral = "User Id=***;Password=*****;Host=" + globalSettings.settingCentralIP + ";Database=" + globalSettings.settingCentralDB; 
      using (MySqlConnection connectionCentral = new MySqlConnection(myConnStringCentral)) 
      { 
       connectionCentral.Open(); 
      } 
      string myConnStringCentralCopy = "User Id=*****;Password=*****;Host=" + globalSettings.settingCentralCopyIP + ";Database=" + globalSettings.settingCentralCopyDB; 
      using (MySqlConnection connectionCentralCopy = new MySqlConnection(myConnStringCentralCopy)) 
      { 
       connectionCentralCopy.Open(); 
      } 
      transScope.Commit(); 
      Console.WriteLine("Transaction is completed"); 
     } 
     catch (Exception) 
     { 
      transScope.RollBack(); 
      Console.WriteLine("Transaction is rolled back"); 
     } 
    } 

Answer 3

當Complete方法被調用，然後在範圍都將被提交，如果沒有Exception拋出。如果代碼在沒有Complete的情況下超出範圍，則不會發生提交。簡而言之，如果您致電Complete方法，那麼，如果沒有Exceptions被拋出，則在給定的TransactionScope範圍內的交易將被提交。

此外，我必須補充說，也可能有一個層次結構，一棵TransactionScopes的樹。您還可以爲TransactionScope的子範圍回滾時的情況設置TransactionScope的行爲。

Answer 4

當您連接到多個數據庫在一個TransactionScope，交易升級爲distributed事務協調使用2-phase commitMSDTC。

關於連接關閉 - 當連接在TransactionScope內關閉時，在內部由基礎設施System.Transactions管理，所以特殊情況下，即使連接從您的端點關閉，數據庫會話仍然可以打開。

查看MSDN這樣一個字條：

未決交易使用Transact-SQL或調用BeginTransaction時，如果啓用了連接池的連接被重置自動回滾啓動。如果連接池關閉，則在調用SqlConnection.Close後，事務將回滾。交易開始通過System.Transactions的是通過System.Transactions的基礎設施控制，並且不會受到SqlConnection.Close

編輯根據您的意見，這裏是你可以做什麼：

try 
{ 
    using (TransactionScope transScope = new TransactionScope()) 
    { 
     string myConnStringLocal = ...; 
     using (var connectionLocal = new MySqlConnection(myConnStringLocal)) 
     { 
     connectionLocal.Open(); 
     // do your DB update 

     } //no need to close connection explicitly, the using() {..} statement does that for you 

     string myConnStringCentral = ...; 
     using (var connectionCentral = new MySqlConnection(myConnStringCentral)) 
     { 
     connectionCentral.Open(); 
     // do your DB update 

     } //no need to close connection explicitly, the using() {..} statement does that for you 

     string myConnStringCentralCopy = ...; 
     using (var connectionCentralCopy = new MySqlConnection(myConnStringCentralCopy)) 
     {   
     connectionCentralCopy.Open(); 
     // do your DB update 

     } //no need to close connection explicitly, the using() {..} statement does that for you 

     transScope.Complete(); 

     Console.WriteLine("Transaction is completed"); 

    } //no need to dispose transactionScope explicitly, the using() {..} statement does that for you 
} 
catch (Exception) 
{ 
     // If any exception occurs in the try block above transScope.Complete() line will be caught here 
     // and will automatically cause the transaction to rollback. 
     Console.WriteLine("Transaction is rolled back"); 
} 

// You can then start new TransactionScope if you want to further update more than one DB in a transactional manner. 
try 
{ 
    using (TransactionScope transScope = new TransactionScope()) 
    { 
     //... 

    } 
} 
catch (Exception) 
{ 
    //... 
}