将SharpArchitecture的NHibernateSession与不同的线程结合使用

Question

我在ASP.NET MVC 3应用程序中使用SharpArchitecture.一切都很美妙.

使用SharpArchitecture的NHibernateInitializer为每个请求初始化一个新的Session,如下所示:

    protected void Application_BeginRequest(object sender, EventArgs e)
    {
        NHibernateInitializer.Instance().InitializeNHibernateOnce(InitializeNHibernateSession);
    }

    private void InitializeNHibernateSession(ISessionStorage sessionStorage)
    {
        NHibernateSession.ConfigurationCache = new NHibernateConfigurationFileCache(
            new[] { "App.Core" });
        NHibernateSession.Init(
            sessionStorage,
            new[] { Server.MapPath("~/bin/" + ApplicationSettings.Instance.NHibernateMappingAssembly) },
            new AutoPersistenceModelGenerator().Generate(),
            Server.MapPath("~/NHibernate.config"));

        NHibernateSession.AddConfiguration(ApplicationSettings.NHIBERNATE_OTHER_DB,
                                           new[] { Server.MapPath("~/bin/" + ApplicationSettings.Instance.NHibernateMappingAssembly) },
                                           new AutoPersistenceModelGenerator().Generate(),
                                           Server.MapPath("~/NHibernateForOtherDb.config"), null, null, null);
    }

如您所见,我们也在访问多个数据库.一切都很好.

这是我遇到问题的地方.

我需要启动一个单独的线程来执行数据库轮询机制.我的意图是做这样的事情:

    protected void Application_Start()
    {
            ....
            ThreadingManager.Instance.ExecuteAction(() =>
            {
                // initialize another NHibernateSession within SharpArchitecture somehow
                NHibernateInitializer.Instance().InitializeNHibernateOnce(InitializeNHibernateSession);

                var service = container.Resolve<IDatabaseSynchronizationService>();
                service.SynchronizeRepositories();
            });
}

通过我的SynchronizationService,一些存储库被调用.显然,当他们尝试访问其会话时,会抛出异常,因为Session为null.

这是我的问题.我如何利用SharpArchitecture的NHibernateSession并以某种方式获得它或它的副本,在我的轮询线程中旋转？我希望这可以在不必绕过使用SharpArchitecture使用的内置SessionManagers和SessionFactories的情况下完成.

Answer 1

我认为这sessionStorage是一个SharpArch.Web.NHibernate.WebSessionStorage对象,对吗？如果是这样那么问题不在于NHibernate会话是空的,它可能在你的线程上,HttpContext.Current为null,而WebSessionStorage对象依赖于HttpContext.Current来完成它的工作(参见这段代码,特别是行37,其中,当从线程调用时,context为null,因此发生null异常).

我认为解决方案是编写一个不同的SessionStorage对象来检查是否HttpContext.Current为null,如果是,则使用线程本地存储来代替存储NHibernate会话(这个解决方案是从其他StackOverflow文章中找到的,该文章讨论了相同的类型事物:在Web应用程序Application_Start方法中初始化NServiceBus时出现NullReferenceException)

编辑

也许这样的东西:

public class HybridWebSessionStorage : ISessionStorage
{

    static ThreadLocal<SimpleSessionStorage> threadLocalSessionStorage;

    public HybridWebSessionStorage( HttpApplication app )
    {
        app.EndRequest += Application_EndRequest;
    }

    public ISession GetSessionForKey( string factoryKey )
    {
        SimpleSessionStorage storage = GetSimpleSessionStorage();
        return storage.GetSessionForKey( factoryKey );
    }

    public void SetSessionForKey( string factoryKey, ISession session )
    {
        SimpleSessionStorage storage = GetSimpleSessionStorage();
        storage.SetSessionForKey( factoryKey, session );
    }

    public System.Collections.Generic.IEnumerable<ISession> GetAllSessions()
    {
        SimpleSessionStorage storage = GetSimpleSessionStorage();
        return storage.GetAllSessions();
    }

    private SimpleSessionStorage GetSimpleSessionStorage()
    {
        HttpContext context = HttpContext.Current;
        SimpleSessionStorage storage;
        if ( context != null )
        {
            storage = context.Items[ HttpContextSessionStorageKey ] as SimpleSessionStorage;
            if ( storage == null )
            {
                storage = new SimpleSessionStorage();
                context.Items[ HttpContextSessionStorageKey ] = storage;
            }
        }
        else
        {
            if ( threadLocalSessionStorage == null )
                threadLocalSessionStorage = new ThreadLocal<SimpleSessionStorage>( () => new SimpleSessionStorage() );
            storage = threadLocalSessionStorage.Value;
        }
        return storage;
    }

    private static readonly string HttpContextSessionStorageKey = "HttpContextSessionStorageKey";

    private void Application_EndRequest( object sender, EventArgs e )
    {
        NHibernateSession.CloseAllSessions();

        HttpContext context = HttpContext.Current;
        context.Items.Remove( HttpContextSessionStorageKey );
    }
}

注意:您必须确保NHibernateSession.CloseAllSessions()在完成线程完成工作后调用,因为当线程完成时,Application_EndRequest不会被触发.