c# – 使用TransactionScopeOption.Suppress与Sql Server Compact 4

我在使用带有Entity Framework和System.Transactions.TransactionScope的sql Server CE 4来抑制部分事务时遇到了问题.

下面的简化代码来自演示问题的单元测试.

我们的想法是在不影响outerScope块(“环境”事务)的情况下启用innerScope块(没有事务)成功或失败.这是TransactionScopeOption.Suppress的既定目的.

但是,代码失败,因为似乎整个SoMetable表被outerScope中的第一个插入锁定.在代码中指示的位置,抛出此错误：

“sql Server Compact等待锁定超时.设备的默认锁定时间为2000ms,桌面的默认锁定时间为5000ms.使用ssce：default lock timeout属性可以在连接字符串中增加默认锁定超时.[Session id = 2,线程id = 2248,进程id = 13516,表名= SoMetable,冲突类型= x锁(x块),资源= PAG(idx)：1046]“

[TestMethod()]
[DeploymentItem("MyLocalDb.sdf")]
public void MyLocalDb_TransactionSuppressed()
{
    int count = 0;

    // This is the ambient transaction
    using (TransactionScope outerScope = new TransactionScope(TransactionScopeOption.required))
    {
        using (MyObjectContext outerContext = new MyObjectContext())
        {
            // Do something in the outer scope
            outerContext.Connection.open();
            outerContext.AddToSoMetable(CreateSoMetableRow());
            outerContext.SaveChanges();
            try
            {
                // Ambient transaction is suppressed for the inner scope of sqlCE operations
                using (TransactionScope innerScope = new TransactionScope(TransactionScopeOption.Suppress))
                {
                    using (MyObjectContext innerContext = new MyObjectContext())
                    {
                        innerContext.Connection.open();
                        // This insert will work
                        innerContext.AddToSoMetable(CreateSoMetableRow());
                        innerContext.SaveChanges(); // ====> EXCEPTION THROWN HERE
                        // There will be other,possibly failing operations here
                    }
                    innerScope.Complete();
                }
            }
            catch { }
        }
        outerScope.Complete();
    }

    count = GetCountFromSoMetable();
    // The insert in the outer scope should succeed,and the one from the inner scope
    Assert.AreEqual(2,count);
}

因此,根据http://msdn.microsoft.com/en-us/library/ms172001,似乎“事务范围中的事务执行时隔离级别设置为Serializable”

但是,使用以下代码段更改TransactionScope的隔离级别无济于事：

public void MyLocalDb_TransactionSuppressed()
{
    Transactionoptions opts = new Transactionoptions();
    opts.IsolationLevel = IsolationLevel.ReadCommitted;
    int count = 0;

    // This is the ambient transaction
    using (TransactionScope outerScope = new TransactionScope(TransactionScopeOption.required,opts))
    ...

在同一位置抛出相同的异常.

似乎避免这种情况的唯一方法是在进入innerScope块之前调用outerScope.Complete().但这会破坏目的.

我在这里错过了什么？
谢谢.

解决方法

AFAIK sql Server Compact不支持嵌套事务.