"Damien" <Damien_The_Unbelie***@hotmail.com> wrote in message
news:1154685389.949962.182950@h48g2000cwc.googlegroups.com...
> Hi guys,
>
> I've got a working project which runs as a service, and performs
> various simple calculations based on data provided to it in a database.
> Other data within the database describes the operations which must be
> performed on the data. (Essentially, there is a table called
> DataItemCalculations, that for each DataItem that is to be computed,
> has a sequence of instructions to a basic stack machine).
>
> At present, the service interprets the operations it must perform. It
> also can compile each calculation into a function (essentially running
> the interpreter, but emitting CodeDom elements instead of actually
> performing the requested operations). All is good. Once the compiled
> version is available, the service starts using this instead of
> interpreting.
>
> However, there is one issue that I am aware of. The service monitors
> it's calculations table for changes. If a change occurs, it dumps it's
> cached version of all of the calculations (and the compiled versions)
> and reloads them from the database. But because my compiled
> calculations are in the main AppDomain, they lurk around and represent
> a memory leak if the contents of the calculations table change
> frequently.
>
> What I would like to do is to place my compiled code into a separate
> AppDomain, that can be Unloaded at the same time as the caches are
> cleared, thus freeing the memory.
>
> Does anyone have some sample code of doing in memory compilation in a
> separate AppDomain? I believe I can build the CodeDom elements in my
> AppDomain and then pass them across, since they all seem to be marked
> as Serializable. I've already changed my compilation so that the
> created classes inherit from MarshalByRefObject, but I'm just finding a
> gap in the mental leap to generating in an alternate AppDomain.
>
> Damien
>
> (Existing compilation code. ccu is the CodeCompileUnit. CompiledDIC is
> an interface which the created class implements, BIL.CompiledDICs is
> the namespace)
>
>      Dim vbp As New Microsoft.VisualBasic.VBCodeProvider
>      Dim comp As Compiler.ICodeCompiler = vbp.CreateCompiler()
>      Dim opts As New Compiler.CompilerParameters
>      opts.GenerateInMemory = True
>      Dim res As Compiler.CompilerResults =
> comp.CompileAssemblyFromDom(opts, ccu)
>      If res.Errors.HasErrors Then
>        Throw New
> StackMachine.StackMachineException(StackMachine.ExceptionCauses.BadProgram,
> "CompileDIC (OnCompile)")
>      End If
>
>      Return
> CType(res.CompiledAssembly.CreateInstance("BIL.CompiledDICs." &
> di.Name.Replace("."c, "_"c)), CompiledDIC)
>