Issues when enabling tracing on gRPC service

[a0viedo]

We were using the latest version of this module but after enabling it we couldn't see any traces whatsoever. After digging we found many of logs with

 severity:  "ERROR"  
 textPayload:  "original object and wrapper must be functions"

We believe it's because of the type checking one of the dependencies is doing (see PR). We found also that switching to versions older to v3.5.0 seems to solve the problem.

Any idea on how to solve the issue for the latest version?

[a0viedo]

Ok got a reproduction: new VM on GCP with this example running:

alejandro@instance-1:~/grpc/examples/node/dynamic_codegen/route_guide$ node -v
v8.15.0
alejandro@instance-1:~/grpc/examples/node/dynamic_codegen/route_guide$ node route_guide_server.js --db_path=./route_guide_db.json 
original object and wrapper must be functions
(node:3834) DeprecationWarning: Server#addProtoService: Use Server#addService instead

Run the client twice, first without any changes and the second time changing routeChat to be an async function. On Stackdriver I see both first calls but no routeChat for the second execution

[kjin]

Your shimmer PR should fix the problem! That being said this bug appears to be in all versions of the module -- it's not specific to 3.5.0.

Since grpc is the only module in which a user's function is directly wrapped via shimmer when it's patched for tracing, I'll go ahead and also open a PR to fix this issue here in case the shimmer PR takes too long to land.

Thanks for bringing this to our attention!