【发布时间】：2012-09-13 08:30:52
【问题描述】：
所以我有一个执行工作流过程的 Windows 服务进程。后端在 Entity Framework 之上使用 Repository 和 UnitofWork Pattern 和 Unity，以及从 edmx 生成的实体类。我不会详细介绍它，因为它不是必需的，但基本上有 5 个工作流程要经过的步骤。一个特定的过程可能在任何时间点的任何阶段（当然是按顺序）。第一步只是为第二步生成数据，第二步通过一个长时间运行的进程验证数据到另一台服务器。然后在那里生成包含该数据的pdf。对于每个阶段，我们都会生成一个计时器，但是可以配置为允许为每个阶段生成多个计时器。问题就在于此。当我将处理器添加到特定阶段时，它随机出现以下错误：
连接没有关闭。连接的当前状态为正在连接。
阅读这似乎很明显，这是因为上下文试图从两个线程访问同一个实体。但这就是让我陷入困境的地方。我能找到的所有信息都表明我们应该为每个线程使用一个实例上下文。据我所知，我在做什么（见下面的代码）。我没有使用单例模式或静态或任何东西，所以我不确定为什么会发生这种情况或如何避免它。我已经在下面发布了我的代码的相关部分供您查看。
基础存储库：
public class BaseRepository
{
/// <summary>
/// Initializes a repository and registers with a <see cref="IUnitOfWork"/>
/// </summary>
/// <param name="unitOfWork"></param>
public BaseRepository(IUnitOfWork unitOfWork)
{
if (unitOfWork == null) throw new ArgumentException("unitofWork");
UnitOfWork = unitOfWork;
}
/// <summary>
/// Returns a <see cref="DbSet"/> of entities.
/// </summary>
/// <typeparam name="TEntity">Entity type the dbset needs to return.</typeparam>
/// <returns></returns>
protected virtual DbSet<TEntity> GetDbSet<TEntity>() where TEntity : class
{
return Context.Set<TEntity>();
}
/// <summary>
/// Sets the state of an entity.
/// </summary>
/// <param name="entity">object to set state.</param>
/// <param name="entityState"><see cref="EntityState"/></param>
protected virtual void SetEntityState(object entity, EntityState entityState)
{
Context.Entry(entity).State = entityState;
}
/// <summary>
/// Unit of work controlling this repository.
/// </summary>
protected IUnitOfWork UnitOfWork { get; set; }
/// <summary>
///
/// </summary>
/// <param name="entity"></param>
protected virtual void Attach(object entity)
{
if (Context.Entry(entity).State == EntityState.Detached)
Context.Entry(entity).State = EntityState.Modified;
}
protected virtual void Detach(object entity)
{
Context.Entry(entity).State = EntityState.Detached;
}
/// <summary>
/// Provides access to the ef context we are working with
/// </summary>
internal StatementAutoEntities Context
{
get
{
return (StatementAutoEntities)UnitOfWork;
}
}
}
StatementAutoEntities 是自动生成的 EF 类。
存储库实现：
public class ProcessingQueueRepository : BaseRepository, IProcessingQueueRepository
{
/// <summary>
/// Creates a new repository and associated with a <see cref="IUnitOfWork"/>
/// </summary>
/// <param name="unitOfWork"></param>
public ProcessingQueueRepository(IUnitOfWork unitOfWork) : base(unitOfWork)
{
}
/// <summary>
/// Create a new <see cref="ProcessingQueue"/> entry in database
/// </summary>
/// <param name="Queue">
/// <see cref="ProcessingQueue"/>
/// </param>
public void Create(ProcessingQueue Queue)
{
GetDbSet<ProcessingQueue>().Add(Queue);
UnitOfWork.SaveChanges();
}
/// <summary>
/// Updates a <see cref="ProcessingQueue"/> entry in database
/// </summary>
/// <param name="queue">
/// <see cref="ProcessingQueue"/>
/// </param>
public void Update(ProcessingQueue queue)
{
//Attach(queue);
UnitOfWork.SaveChanges();
}
/// <summary>
/// Delete a <see cref="ProcessingQueue"/> entry in database
/// </summary>
/// <param name="Queue">
/// <see cref="ProcessingQueue"/>
/// </param>
public void Delete(ProcessingQueue Queue)
{
GetDbSet<ProcessingQueue>().Remove(Queue);
UnitOfWork.SaveChanges();
}
/// <summary>
/// Gets a <see cref="ProcessingQueue"/> by its unique Id
/// </summary>
/// <param name="id"></param>
/// <returns></returns>
public ProcessingQueue GetById(int id)
{
return (from e in Context.ProcessingQueue_SelectById(id) select e).FirstOrDefault();
}
/// <summary>
/// Gets a list of <see cref="ProcessingQueue"/> entries by status
/// </summary>
/// <param name="status"></param>
/// <returns></returns>
public IList<ProcessingQueue> GetByStatus(int status)
{
return (from e in Context.ProcessingQueue_SelectByStatus(status) select e).ToList();
}
/// <summary>
/// Gets a list of all <see cref="ProcessingQueue"/> entries
/// </summary>
/// <returns></returns>
public IList<ProcessingQueue> GetAll()
{
return (from e in Context.ProcessingQueue_Select() select e).ToList();
}
/// <summary>
/// Gets the next pending item id in the queue for a specific work
/// </summary>
/// <param name="serverId">Unique id of the server that will process the item in the queue</param>
/// <param name="workTypeId">type of <see cref="WorkType"/> we are looking for</param>
/// <param name="operationId">if defined only operations of the type indicated are considered.</param>
/// <returns>Next pending item in the queue for the work type or null if no pending work is found</returns>
public int GetNextPendingItemId(int serverId, int workTypeId, int? operationId)
{
var id = Context.ProcessingQueue_GetNextPending(serverId, workTypeId, operationId).SingleOrDefault();
return id.HasValue ? id.Value : -1;
}
/// <summary>
/// Returns a list of <see cref="ProcessingQueueStatus_dto"/>s objects with all
/// active entries in the queue
/// </summary>
/// <returns></returns>
public IList<ProcessingQueueStatus_dto> GetActiveStatusEntries()
{
return (from e in Context.ProcessingQueueStatus_Select() select e).ToList();
}
/// <summary>
/// Bumps an entry to the front of the queue
/// </summary>
/// <param name="processingQueueId"></param>
public void Bump(int processingQueueId)
{
Context.ProcessingQueue_Bump(processingQueueId);
}
}
我们使用Unity进行依赖注入，例如一些调用代码：
#region Members
private readonly IProcessingQueueRepository _queueRepository;
#endregion
#region Constructors
/// <summary>Initializes ProcessingQueue services with repositories</summary>
/// <param name="queueRepository"><see cref="IProcessingQueueRepository"/></param>
public ProcessingQueueService(IProcessingQueueRepository queueRepository)
{
Check.Require(queueRepository != null, "processingQueueRepository is required");
_queueRepository = queueRepository;
}
#endregion
windows服务中启动定时器的代码如下：
_staWorkTypeConfigLock.EnterReadLock();
foreach (var timer in from operation in (from o in _staWorkTypeConfig.WorkOperations where o.UseQueueForExecution && o.AssignedProcessors > 0 select o)
let interval = operation.SpawnInternval < 30 ? 30 : operation.SpawnInternval
select new StaTimer
{
Interval = _runImmediate ? 5000 : interval*1000,
Operation = (ProcessingQueue.RequestedOperation) operation.OperationId
})
{
timer.Elapsed += ApxQueueProcessingOnElapsedInterval;
timer.Enabled = true;
Logger.DebugFormat("Queue processing for operations of type {0} will execute every {1} seconds", timer.Operation, timer.Interval/1000);
}
_staWorkTypeConfigLock.ExitReadLock();
StaTimer 只是对定时器添加操作类型的封装。 ApxQueueProcessingOnElapsedInterval 然后基本上只是根据操作将工作分配给进程。
我还将在我们生成任务的地方添加一些 ApxQueueProcessingOnElapsedInterval 代码。
_staTasksLock.EnterWriteLock();
for (var x = 0; x < tasksNeeded; x++)
{
var t = new Task(obj => ProcessStaQueue((QueueProcessConfig) obj),
CreateQueueProcessConfig(true, operation), _cancellationToken);
_staTasks.Add(new Tuple<ProcessingQueue.RequestedOperation, DateTime, Task>(operation, DateTime.Now,t));
t.Start();
Thread.Sleep(300); //so there are less conflicts fighting for jobs in the queue table
}
_staTasksLock.ExitWriteLock();
【问题讨论】：
-
你是 IoC 容器
Dispose上下文实例吗？
标签： multithreading entity-framework dbcontext