c# - 序列化/反序列化 "NHibernate Session"，延迟初始化错误 ("StateServer mode"集群)

Question

我在我的应用程序中使用了一种“每次 session session ”模式实现。在这种方法中，“NHibernate session ”保留在“HTTP session ”中。在每个“Http Request”中，“NHibernate Session”在请求开始时重新连接并在请求结束时断开连接。 “NHibernate Session”在“ session ”结束时保存在“HTTP Session”中。这工作得很好。

问题:

现在我正在考虑使用 "StateServer mode"在“Http session ”上。因此，“HTTP Session”中的所有对象都必须是可序列化的，包括“NHibernate Session”。

所以我正在进行概念验证，以验证“NHibernate Session”及其缓存对象的序列化/反序列化是否有效。

“概念验证”是以下单元测试。目标是让它通过。

代码:

/*069*/  [Test]
/*070*/  public void Test()
/*071*/  {
/*072*/      //for inspecting the SQL commands
/*073*/      NhSqlLogCapture hhSqlLogCapture = new NhSqlLogCapture();
/*074*/  
/*075*/      MemoryStream ms = new MemoryStream();
/*076*/  
/*077*/      ISession sessionBefore = null;
/*078*/      ISession sessionAfter = null;
/*079*/  
/*080*/      //querying before the serialization.
/*081*/      try
/*082*/      {
/*083*/          sessionBefore = this.sessionFactory.OpenSession();
/*084*/          sessionBefore.FlushMode = FlushMode.Auto;
/*085*/  
/*086*/          hhSqlLogCapture.Enable();
/*087*/  
/*088*/          //Querying only 'DetailEtt'
/*089*/          hhSqlLogCapture.SqlStatments.Clear();
/*090*/          ICriteria crt = sessionBefore.CreateCriteria<DetailEtt>();
/*091*/          crt
/*092*/              .SetFetchMode("Master", FetchMode.Select);
/*093*/          IList<DetailEtt> cen1DetailList = crt.List<DetailEtt>();
/*094*/  
/*095*/          //BEGIN: Serializing
/*096*/          //also serializing an instance of 'DetailEtt' to verify that keeps only one instance to the same database record.
/*097*/          sessionBefore.Disconnect();
/*098*/          Object[] serializationArray = new object[] { sessionBefore, sessionBefore.Get<DetailEtt>(1) };
/*099*/          BinaryFormatter bf = new BinaryFormatter();
/*100*/          bf.Serialize(ms, serializationArray);
/*101*/          //END: Serializing
/*102*/  
/*103*/          //assertions
/*104*/          //Checking the sql command executed.
/*105*/          Assert.AreEqual(1, hhSqlLogCapture.SqlStatments.Count, "hhSqlLogCapture.SqlStatments.Count");
/*106*/          Regex rx = new Regex("(?is).*SELECT.*FROM.*DETAIL.*");
/*107*/          Assert.IsTrue(rx.IsMatch(hhSqlLogCapture.SqlStatments[0]), hhSqlLogCapture.SqlStatments[0]);
/*108*/  
/*109*/          hhSqlLogCapture.Disable();
/*110*/      }
/*111*/      finally
/*112*/      {
/*113*/          sessionBefore = null;
/*114*/      }
/*115*/  
/*116*/      try
/*117*/      {
/*118*/          //BEGIN: Deserializing
/*119*/          BinaryFormatter bf = new BinaryFormatter();
/*120*/          ms.Seek(0, SeekOrigin.Begin);
/*121*/          Object[] deserializationArray = (Object[])bf.Deserialize(ms);
/*122*/          DetailEtt dtEttDeserialized = (DetailEtt)deserializationArray[1];
/*123*/          sessionAfter = (ISession)deserializationArray[0];
/*124*/          //BEGIN: Deserializing
/*125*/  
/*126*/          IDbConnection conn = this.dbProvider.CreateConnection();
/*127*/          conn.Open();
/*128*/          sessionAfter.Reconnect(conn);
/*129*/  
/*130*/          //Enabling again because the session loses the reference to the log (I think).
/*131*/          hhSqlLogCapture.Enable();
/*132*/          hhSqlLogCapture.SqlStatments.Clear();
/*133*/  
/*134*/          DetailEtt dtEtdSSGet = sessionAfter.Get<DetailEtt>(1);
/*135*/          MasterEtt mtEtd = dtEtdSSGet.Master;
/*136*/          Console.WriteLine(mtEtd.Description);
/*137*/  
/*138*/          //assertions
/*139*/          //Checking the sql command executed.
/*140*/          Assert.AreEqual(1, hhSqlLogCapture.SqlStatments.Count, "hhSqlLogCapture.SqlStatments.Count");
/*141*/          Regex rx = new Regex("(?is).*SELECT.*FROM.*MASTER.*");
/*142*/          Assert.IsTrue(rx.IsMatch(hhSqlLogCapture.SqlStatments[0]), hhSqlLogCapture.SqlStatments[0]);
/*143*/          //verify that keeps only one instance to the same database record
/*144*/          Assert.AreSame(dtEttDeserialized, dtEtdSSGet, "verify that keeps only one instance to the same database record");
/*145*/      }
/*146*/      finally
/*147*/      {
/*148*/          sessionAfter.Close();
/*149*/      }
/*150*/  }

测试几乎通过了所有内容。但是当尝试加载一个“懒惰”的实体时它会失败。

错误:

SofPOC.Questions.SerializeSession.SerializeSessionTest.Test:
  NHibernate.LazyInitializationException : Initializing[SofPOC.Questions.SerializeSession.Entities.MasterEtt#5]-Could not initialize proxy - no Session.    em NHibernate.Proxy.AbstractLazyInitializer.Initialize()
at NHibernate.Proxy.AbstractLazyInitializer.Initialize()
at Spring.Data.NHibernate.Bytecode.LazyInitializer.Invoke(IMethodInvocation invocation) in c:\_prj\spring-net\trunk\src\Spring\Spring.Data.NHibernate21\Data\NHibernate\Bytecode\LazyInitializer.cs:line 101
at Spring.Aop.Framework.AbstractMethodInvocation.Proceed() in c:\_prj\spring-net\trunk\src\Spring\Spring.Aop\Aop\Framework\AbstractMethodInvocation.cs:line 284
at Spring.Aop.Framework.DynamicProxy.AdvisedProxy.Invoke(Object proxy, Object target, Type targetType, MethodInfo targetMethod, MethodInfo proxyMethod, Object[] args, IList interceptors) in c:\_prj\spring-net\trunk\src\Spring\Spring.Aop\Aop\Framework\DynamicProxy\AdvisedProxy.cs:line 208
at DecoratorAopProxy_9872659265c04d36bc9738f2aaddfb08.get_Description()
at SofPOC.Questions.SerializeSession.SerializeSessionTest.Test() in C:\Users\hailtondecastro\lixo\stackoverflow\dotnet\StackoverflowNetPOCs_20120718\src\SofPOC.Net4.NH2.Spring13.2010\Questions\SerializeSession\SerializeSessionTest.cs:line 136

详细信息:

[Serializable]
public class DetailEtt
{
    private Int32? id;
    /// <summary>
    /// PK
    /// </summary>
    public virtual Int32? Id
    {
        get { return id; }
        set { id = value; }
    }

    private String description;
    /// <summary>
    /// TODO:
    /// </summary>
    public virtual String Description
    {
        get { return description; }
        set { description = value; }
    }

    private MasterEtt master;
    /// <summary>
    /// TODO:
    /// </summary>
    public virtual MasterEtt Master
    {
        get { return master; }
        set { master = value; }
    }
}

MasterEtt:

[Serializable]
public class MasterEtt
{
    private Int32? id;
    /// <summary>
    /// PK
    /// </summary>
    public virtual Int32? Id
    {
        get { return id; }
        set { id = value; }
    }

    private String description;
    /// <summary>
    /// TODO:
    /// </summary>
    public virtual String Description
    {
        get { return description; }
        set { description = value; }
    }
}

DetailEtt.hbm.xml:

<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="SofPOC.Questions.SerializeSession.Entities" assembly="SofPOC.Net4.NH2.Spring13">
  <class name="DetailEtt" table="DETAIL">
    <id name="Id" type="Int32">
      <column name="ID" sql-type="INTEGER"></column>
      <generator class="assigned"></generator>
    </id>
    <property name="Description" type="String">
      <column name="DESCRIPTION" sql-type="VARCHAR( 100 )"></column>
    </property>
    <many-to-one name="Master" fetch="select">
      <column name="MS_ID" sql-type="INTEGER"></column>
    </many-to-one>
  </class>
</hibernate-mapping>

MasterEtt.hbm.xml:

<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="SofPOC.Questions.SerializeSession.Entities" assembly="SofPOC.Net4.NH2.Spring13">
  <class name="MasterEtt" table="MASTER">
    <id name="Id" type="Int32">
      <column name="ID" sql-type="INTEGER"></column>
      <generator class="assigned"></generator>
    </id>
    <property name="Description" type="String">
      <column name="DESCRIPTION" sql-type="VARCHAR( 100 )"></column>
    </property>
  </class>
</hibernate-mapping>

问题:

即使在重新连接反序列化的“Hibernate Session”后，我也会收到“Lazy Load Error”。如何在不必重新附加实体的情况下避免这种“延迟加载错误”？

我正在使用:

• Spring.Net 1.3.2
• NHibernate 2.1.2
• System.Data.SQLite 1.0.80.0

完整的来源在这里:Q11553780.7z

注意事项:

• 在打开解决方案(“.\Src\SofPOC.2010.sln”)之前运行“.\Dependencies\setup.bat”以加载依赖项。
• 有关依赖项的说明，请参阅“.\readme.txt”和“.\dependencies\readme.txt”。

已编辑:

我发现问题的原因出在NHibernate的NHibernate.Proxy.AbstractLazyInitializer类中。字段 _session 标记为 [NonSerialized]。这使得该字段不被序列化。因此它在反序列化后为 null。

查看代码:

namespace NHibernate.Proxy
{
    [Serializable]
    public abstract class AbstractLazyInitializer : ILazyInitializer
    {
        /// <summary>
        /// If this is returned by Invoke then the subclass needs to Invoke the
        /// method call against the object that is being proxied.
        /// </summary>
        protected static readonly object InvokeImplementation = new object();

        private object _target = null;
        private bool initialized;
        private object _id;
        [NonSerialized]
        private ISessionImplementor _session;
        ...

编辑 2:

问题的原因实际上是 [NonSerialized] 属性，因为当我进行以下“hack”时，测试通过了。通过反射(reflection)，我将“_session”的属性从“Private | NotSerialized”更改为仅“Private”。

黑客:

    protected override void OnSetUp()
    {
        //Hacking "_session"
        Type aliType = Type.GetType("NHibernate.Proxy.AbstractLazyInitializer, NHibernate");
        FieldInfo fiSession = aliType.GetField("_session", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
        FieldInfo fi_m_fieldAttributes =
            fiSession.GetType().GetField(
                "m_fieldAttributes", 
                System.Reflection.BindingFlags.NonPublic 
                    | System.Reflection.BindingFlags.Instance);
        // changing it from "Private | NotSerialized" to only "Private"
        fi_m_fieldAttributes.SetValue(fiSession, FieldAttributes.Private);

        base.OnSetUp();
    }

Answer 1

据我所知，可以尝试三种选择:

1. 使用反射设置反序列化 session 的_session字段
2. 打开一个新 session 并重新连接它们。这样做可能会很痛苦，但我认为，如果 NHibernate 团队让做某事变得困难，他们可能有充分的理由。
3. 创建您自己的 ILazyInitializer。 ServerSide有一篇文章讲过here .我自己还没有尝试过。

如果您尝试 nr 1，请告诉我们它是否有效。我很想看看会发生什么。理论上它应该有效。