OdataToEntity.EfCore.DynamicDataContext, DynamicTypeDefinitionManager and LRU caching about odatatoentity

[voronov-maxim]

You can show example code in TypeResolve method?

[dshalkhakov]

Somewhere early in program startup, and done exactly once:

System.AppDomain.CurrentDomain.TypeResolve += HandleTypeResolve

Then the HandleTypeResolve will be called when DynamicTypeDefinitionManager looks for a db context type using Type.GetType and doesn't find it.

And in HandleTypeResolve we'll look up the type in cache, generate it if needed, and then return it, like so (in pseudocode):

private System.Reflection.Assembly HandleTypeResolve(object sender, System.ResolveEventArgs args)
{
    if (_dynamicTypeService.IsDynamicContext(args.Name))
    {
        return _dynamicTypeService.GetOrCreateDynamicContext(args.Name);
    }
    return null;
}

But the problem remains that the DynamicTypeDefinitionManager [1] is implemented in such a way that new types need to be generated over and over again and never be disposed of/re-used.

How about introducing

1. dynamic type generation instead of [2][3]
2. LRU cache for said DynamicTypeDefinitionManager?

[1]

OdataToEntity/source/OdataToEntity.EfCore.DynamicDataContext/DynamicTypeDefinitionManager.cs

Line 22 in addf0b4

private static int _dynamicDbContextIndex;

[2] https://github.com/voronov-maxim/OdataToEntity/blob/master/source/OdataToEntity.EfCore.DynamicDataContext/Types/DynamicDbContexts.cs
[3] https://github.com/voronov-maxim/OdataToEntity/blob/master/source/OdataToEntity.EfCore.DynamicDataContext/Types/DynamicTypes.cs

EDIT: formatting

[voronov-maxim]

Hi @dshalkhakov!

OdataToEntity/test/OdataToEntity.Test.DynamicDataContext.AspServer/Startup.cs

Line 73 in ce85dec

IEdmModel edmModel = DynamicMiddlewareHelper.CreateEdmModel(providerSchema, informationSchemaSettings);

must be

IEdmModel edmModel = DynamicMiddlewareHelper.CreateEdmModelViaEmit(providerSchema, informationSchemaSettings);

[dshalkhakov]

Hi @voronov-maxim. I've looked into that method and the commit it appears in. It looks like it'd do the trick.
I wonder why it hasn't been released yet. Any reasons?

[dshalkhakov]

I've also looked into the current source [1][2] and it seems DynamicDbContexts are still not generated dynamically. A custom EmitDynamicTypeDefinitionManagerFactory might rectify that.

[1]

OdataToEntity/source/OdataToEntity.EfCore.DynamicDataContext/EmitDynamicTypeDefinitionManager.cs

Line 13 in ce85dec

return EmitDynamicTypeDefinitionManager.Create(metadataProvider, CreateDynamicDbContextType());

[2]

OdataToEntity/source/OdataToEntity.EfCore.DynamicDataContext/DynamicTypeDefinitionManagerFactory.cs

Line 18 in ce85dec

{

[voronov-maxim]

Release nuget 2.6.1

To create a DynamicDbContext, an emit constructor is required. I do not see the need for this since only one context is used by default. Several contexts are used for xunit tests.