Hangfire 事务流程（工作单元）

Question

在下面的.Net Framework代码中，确保将某个Entity对象插入到数据库中，然后执行发布操作。然而，在.Net Core 中我无法做到这一点。当我尝试运行这段代码时，发生平台异常。

using (var transaction = new TransactionScope())
{
    SomeEntity someEntity = new SomeEntity();
    someEntity.Gui = Guid.NewGuid().ToString();

    _dataContext.SomeEntities.Add(someEntity);
    _dataContext.SaveChanges();

    _backgroundJobClient.Enqueue(() => PublishSomeEntityCreatedEvent(someEntity.Id)));

    transaction.Complete();
}

对于这种情况有什么好的解决方案吗？

注意：.Net Core 2.2控制台应用程序、EntityFrameworkCore 2.1和Hangfire 1.6.21用于测试

---

更新：整个堆栈跟踪

Hangfire.BackgroundJobClientException: Background job creation failed. See inner exception for details. ---> System.PlatformNotSupportedException: This platform
 does not support distributed transactions.
   at System.Transactions.Distributed.DistributedTransactionManager.GetDistributedTransactionFromTransmitterPropagationToken(Byte[] propagationToken)
   at System.Transactions.TransactionInterop.GetDistributedTransactionFromTransmitterPropagationToken(Byte[] propagationToken)
   at System.Transactions.TransactionStatePSPEOperation.PSPEPromote(InternalTransaction tx)
   at System.Transactions.TransactionStateDelegatedBase.EnterState(InternalTransaction tx)
   at System.Transactions.EnlistableStates.Promote(InternalTransaction tx)
   at System.Transactions.Transaction.Promote()
   at System.Transactions.TransactionInterop.ConvertToDistributedTransaction(Transaction transaction)
   at System.Transactions.TransactionInterop.GetExportCookie(Transaction transaction, Byte[] whereabouts)
   at System.Data.SqlClient.SqlInternalConnection.GetTransactionCookie(Transaction transaction, Byte[] whereAbouts)
   at System.Data.SqlClient.SqlInternalConnection.EnlistNonNull(Transaction tx)
   at System.Data.SqlClient.SqlInternalConnection.Enlist(Transaction tx)
   at System.Data.SqlClient.SqlInternalConnectionTds.Activate(Transaction transaction)
   at System.Data.ProviderBase.DbConnectionInternal.ActivateConnection(Transaction transaction)
   at System.Data.ProviderBase.DbConnectionPool.PrepareConnection(DbConnection owningObject, DbConnectionInternal obj, Transaction transaction)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Hangfire.SqlServer.SqlServerStorage.CreateAndOpenConnection()
   at Hangfire.SqlServer.SqlServerStorage.UseConnection[T](DbConnection dedicatedConnection, Func`2 func)
   at Hangfire.SqlServer.SqlServerConnection.CreateExpiredJob(Job job, IDictionary`2 parameters, DateTime createdAt, TimeSpan expireIn)
   at Hangfire.Client.CoreBackgroundJobFactory.Create(CreateContext context)
   at Hangfire.Client.BackgroundJobFactory.<>c__DisplayClass7_0.<CreateWithFilters>b__0()
   at Hangfire.Client.BackgroundJobFactory.InvokeClientFilter(IClientFilter filter, CreatingContext preContext, Func`1 continuation)
   at Hangfire.Client.BackgroundJobFactory.<>c__DisplayClass7_1.<CreateWithFilters>b__2()
   at Hangfire.Client.BackgroundJobFactory.CreateWithFilters(CreateContext context, IEnumerable`1 filters)
   at Hangfire.Client.BackgroundJobFactory.Create(CreateContext context)
   at Hangfire.BackgroundJobClient.Create(Job job, IState state)
   --- End of inner exception stack trace ---
   at Hangfire.BackgroundJobClient.Create(Job job, IState state)
   at Hangfire.BackgroundJobClientExtensions.Create(IBackgroundJobClient client, Expression`1 methodCall, IState state)
   at Hangfire.BackgroundJobClientExtensions.Enqueue(IBackgroundJobClient client, Expression`1 methodCall)
   at TopShelf_Hangfire_NetCore.BusinessService.Execute(DateTime utcNow) in C:\Projects\Practices\TopShelf_Hangfire_NetCore\BusinessService.cs:line 31
   at TopShelf_Hangfire_NetCore.StartupService._timer_Elapsed(Object sender, ElapsedEventArgs e) in C:\Projects\Practices\TopShelf_Hangfire_NetCore\StartupService.cs:line 35

Answer 1

看起来正在启动 distrubutrd 事务，但 .net core 不支持该事务。

由于您正在访问多个资源管理器（您的数据库和hangfire 的数据库），transactionscope 会尝试升级要分配的事务。

您可以将hangfire 排除_backgroundJobClient.Enqueue() 在范围之外，这样升级就不会发生。

您将必须找到另一种方法来确保执行这两个操作（数据库更新、hangfire 排队）

编辑：由于您无法进行事务，因此您必须设计服务来处理可能的故障情况。例如：帐户服务将：

1. 将创建的内容保留到数据库

2. 然后调用hangfire Enqueue

3. 记录在同一用户数据库中创建hangfire作业的事实。

4. 用户服务必须轮询数据库，以查看是否创建了用户但未记录通知。

其他微服务应该能够处理重复的通知。

这样，如果创建了用户但未发送通知，您的服务将重新发送 (4)。

如果在 (2) 和 (3) 之间发生故障，接收服务将忽略重复请求