Question

重新分配Transaction.Current时，我似乎失去了TransactionScopeAsyncFlowOption原来的TransactionScope行为。第二个await之后的代码丢失了Transaction.Current值。

示例代码（Linqpad）：

async Task Main()
{
    Thread.CurrentThread.ManagedThreadId.Dump("before await");
    var scope = new TransactionScope(TransactionScopeOption.Required, TransactionScopeAsyncFlowOption.Enabled);
    var transaction = Transaction.Current;

    await Task.Delay(1000).ConfigureAwait(false);

    Thread.CurrentThread.ManagedThreadId.Dump("after first await");
    Transaction.Current = transaction;
    Transaction.Current.Dump(); // not null

    await Task.Delay(1000).ConfigureAwait(false);

    Thread.CurrentThread.ManagedThreadId.Dump("after second await");
    Transaction.Current.Dump(); // is null :/
}

我know应该在using上使用TransactionScope语句，而不是重新分配环境事务，但是由于某些原因，不可能这样做。我对以上代码段行为的原因感到好奇，并想知道是否存在保持原始TransactionScopeAsyncFlowOption行为的方法。

Answer 1

我通过将Transaction对象包装到另一个TransactionScope中并启用了TransactionScopeAsyncFlowOption来解决了这个问题：

async Task Main()
{
    var scope = new TransactionScope(TransactionScopeOption.Required, TransactionScopeAsyncFlowOption.Enabled);
    var transaction = Transaction.Current;

    await Task.Delay(1000);

    Transaction.Current = transaction;
    Debug.Assert(Transaction.Current != null); // not null

    await Task.Delay(1000);

    Debug.Assert(Transaction.Current == null); // is null :/

    using (var innerScope = new TransactionScope(transaction, TransactionScopeAsyncFlowOption.Enabled))
    {
        // Transaction.Current state is kept across async continuations
        Debug.Assert(Transaction.Current != null); // not null
        await Task.Delay(10);
        Debug.Assert(Transaction.Current != null); // not null
        innerScope.Complete();
    }
}

重新分配事务时上下文丢失。异步/等待代码中的当前

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