Is it possible to set the default Serializer to a pre-compiled one in protobuf-net?

Question

I am using protobuf-net with protobuf-net.grpc and am attempting to get it to work on Xmarin/Ios.

Currently I have attempted to create a pre-compiled serializer:

            RuntimeTypeModel runtimeTypeModel = RuntimeTypeModel.Create();
            runtimeTypeModel.AllowParseableTypes = true;
            runtimeTypeModel.AutoAddMissingTypes = true;
            runtimeTypeModel.AutoCompile = false;
            runtimeTypeModel.Add(typeof(UserInfo), true);
            Directory.SetCurrentDirectory(@"..\..\");
            runtimeTypeModel.Compile("PDASerializers", @"PDASerializers.dll");

When i reference this .dll and do new PDASerializers().Serialize(new UserInfo()) it works without issues.

I am however walking into a brick wall when attempting to go all in into awesomeness and use protobuf-net.grpc.

The issue is that as soon as I call: channel.CreateGrpcService<ISomeInterface> I get a reflection.emit error:

Operation is not supported on this platform.

  at System.Reflection.Emit.AssemblyBuilder.DefineDynamicAssembly (System.Reflection.AssemblyName name, System.Reflection.Emit.AssemblyBuilderAccess access) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/Current/src/Xamarin.iOS/mcs/class/corlib/System.Reflection.Emit/AssemblyBuilder.pns.cs:129 
  at ProtoBuf.Grpc.Internal.ProxyEmitter..cctor () [0x0001e] in /_/src/protobuf-net.Grpc/Internal/ProxyEmitter.cs:18

nb.

I read at various places turning off "AutoCompile" could be a work around. This did solve me nog begin able to call Serialize directly - so it would seem I have no need for a pre-compiled serializer.

After some digging into the inner workings of protobuf I attempted to do this:

typeof(TypeModel).GetMethod("SetDefaultModel", BindingFlags.NonPublic | BindingFlags.Static).Invoke(null, new object[] { new PDASerializers() })

But regretfully this also did not solve the issue.

Concretely my question is as follows;

Is it possible to either replace the default serializer to use the pre-compiled one in protobuf-net.grpc or is there some other way to turn off "AutoCompile" globally (so also for protobuf-net.grpc)?

score 1 · Accepted Answer · answered Jun 25 '20 at 17:13

A second read on this reveals that you're actually looking for gRPC support. This is actually possible right now - you just need to provide a custom binder config:

var binderConfig = BinderConfiguration.Create(new List<MarshallerFactory> {
    ProtoBufMarshallerFactory.Create(yourModelHere)
});

Now you can use that binderConfig when creating clients (or registering servers, if you like), and: it should all work.

As for the pre-compile bit:

The answer here is complex. V3 is designed to facilitate this exact scenario - but the build time bits (aka "generators") is not yet complete (it is a C# vNext/preview feature that we've been waiting on specifically for this).

Additionally, V3 splits the core and reflection pieces in half, specifically to reduce the reference surface area when you aren't using those features.

For can it be done today: yes, but right now it is a little awkward, while the dust settles. If you have a modest sized example I'd be happy to work with you to get something working. To demonstrate that it can be done: https://protogen.marcgravell.com/decode does exactly this today, and can successfully run in the browser via Blazor with zero runtime emit - it has pre-compiled serializers for the FileDescriptorSet etc that is uses when needed.

Thank you! Yeah, regretfully I was unable to attach tag protobuf-net.grpc - it does not exist yet. — RichardVNL, Jun 26 '20 at 09:08
@RichardVNL fixed that, ta; any problems with the binder: let me know — Marc Gravell, Jun 26 '20 at 09:54
@MarcGravell are we able to get an update on this answer? Also to the original question asker RichardVNL is this some to improve performance and or decrease the use of reflection? — rollsch, Nov 30 '22 at 18:38
@rollsch full AOT is likely to be v4; and "yes, both of those" — Marc Gravell, Dec 01 '22 at 14:15

Is it possible to set the default Serializer to a pre-compiled one in protobuf-net?

1 Answers1