ODP.NET

Hello.

I tried to avoid Oracle limitation of 1000 items for “IN” operator at maximum in out .NET project using following UDT:

CREATE OR REPLACE TYPE array_long AS TABLE OF NUMBER(10,0);

I have prepared a simple demo project and everything was working. Then I tried to implement this solution to our project and an unexpected problem appeared:

System.NullReferenceException
 HResult=0x80004003
 Message=Object reference not set to an instance of an object.
 Source=Oracle.ManagedDataAccess
 StackTrace:
  at Oracle.ManagedDataAccess.Types.OracleUdt.GetAllReferencedAssemblies() in Oracle.ManagedDataAccess.Types\OracleUdt.cs:line 752

When OracleUdt tries to search for OracleCustomTypeMappingAttribute in all loaded assemblies the function GetAllReferencedAssemblies() finds in my case 15 assemblies. The first one (by a chance or because stack is used?) is something called “Anonymously Hosted DynamicMethods Assembly”.

The FullName of this assembly is added to the collection of possible ones and later Assembly.Load(…) is called for this FullName. But this assembly cannot be loaded by its nature, so exception is raised and catched and variable assembly2 contains null value.

This variable is used to call hashtable.Contains(assembly2.FullName) and the exception “Object reference not set” is raised…

It seems this “Anonymously Hosted DynamicMethods Assembly” was created in runtime by some other library referenced from our project (could be OllamaSharp.dll which is not used in my simple demo project). This assembly is system and quite special and cannot be loaded - according to StackOverflow here:

https://stackoverflow.com/questions/2636141/what-exactly-is-the-anonymously-hosted-dynamicmethods-assembly-and-how-can-i-m

Possible easy solutions:

• check if assembly2 after Assembly.LoadFrom() is null or not
• add problematic assembly to the list of excluded assemblies (s_ODPExcludedAssembliesList) in OracleUdt2 constructor

The version of ODP used in our project is Oracle.ManagedDataAccess.Core 23.26.200.

Would be nice to have this fixed. :-)

Mirek

PS: The declaration of variable assembly2 should be moved into while loop to avoid re-using its value in case the assembly cannot be loaded.

PS2: The decompiled code of OracleUdt2 with my comments what is happening:

internal static ArrayList GetAllReferencedAssemblies()
{
    Hashtable hashtable = new Hashtable();
    Hashtable hashtable2 = new Hashtable();
    Stack stack = new Stack();
    Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies(); // finds problematic assembly
    foreach (Assembly assembly in assemblies)
    {
        if (!IsExcludedAssembly(assembly)) // problematic assembly is not excluded
        {
            if (!assembly.IsDynamic && !hashtable2.Contains(assembly.FullName))
            {
                hashtable2.Add(assembly.FullName, assembly.Location);
            }
            stack.Push(assembly.FullName); // adds problematic assembly to possible ones
        }
    }
    Assembly assembly2 = null;
    while (stack.Count > 0)
    {
        try
        {
            string text = (string)stack.Pop(); // gets "Anonymously Hosted DynamicMethods Assembly, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null"
            try
            {
                assembly2 = Assembly.Load(text); // fails to load problematic assembly => exception
            }
            catch
            {
                if (hashtable2.Contains(text)) // not contained in hashtable2
                {
                    assembly2 = Assembly.LoadFrom((string)hashtable2[text]);
                }
            }
            ...
            if (!hashtable.Contains(assembly2.FullName)) // exception because assembly2 is null
            {
                hashtable.Add(assembly2.FullName, assembly2);
            }

The properties of “Anonymously Hosted DynamicMethods Assembly” (IsDynamic = True, Location = “”):

-        assembly    {Anonymously Hosted DynamicMethods Assembly, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null}    System.Reflection.Assembly {System.Reflection.RuntimeAssembly}
        CodeBase    "file:///C:/.../bin/Debug/net8.0/OllamaSharp.dll"    string
       CustomAttributes    {System.Reflection.CustomAttributeData[0]}    System.Collections.Generic.IEnumerable<System.Reflection.CustomAttributeData> {System.Reflection.CustomAttributeData[]}
       DefinedTypes    {System.RuntimeType[0]}    System.Collections.Generic.IEnumerable<System.Reflection.TypeInfo> {System.RuntimeType[]}
        EntryPoint    null    System.Reflection.MethodInfo
        EscapedCodeBase    "file:///C:/.../bin/Debug/net8.0/OllamaSharp.dll"    string
        ExportedTypes    {System.Type[0]}    System.Collections.Generic.IEnumerable<System.Type> {System.Type[]}
        FullName    "Anonymously Hosted DynamicMethods Assembly, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null"    string
        GlobalAssemblyCache    false    bool
        HostContext    0    long
        ImageRuntimeVersion    ""    string
        IsCollectible    false    bool
        IsDynamic    true    bool
        IsFullyTrusted    true    bool
        Location    ""    string
+        ManifestModule    {RefEmit_InMemoryManifestModule}    System.Reflection.Module {System.Reflection.RuntimeModule}
+        Modules    {System.Reflection.RuntimeModule[1]}    System.Collections.Generic.IEnumerable<System.Reflection.Module> {System.Reflection.RuntimeModule[]}
        ReflectionOnly    false    bool
        SecurityRuleSet    None    System.Security.SecurityRuleSet
        SyncRoot    {object}    object
        _ModuleResolve    null    System.Reflection.ModuleResolveEventHandler
        m_assembly    0x0000017ab8aa6450    System.IntPtr
        m_fullname    "Anonymously Hosted DynamicMethods Assembly, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null"    string
        m_syncRoot    {object}    object
+        Static members