Byte Buddy for real-time systems

[druzhynin-oleksii]

Hi.

We have very special case which exists only in real-time bidding and self-driving.

We have real-time Java agent which has 500+ input parameters from data sources and should answer within 300ms. To debug we need a sample of that input parameters and a outside environment reaction which very hard to simulate.

So we need to run our engine twice for debug:

1. to get the environment reaction
2. to collect debugged parameters (which set can be varied)

Can we use Byte Buddy for the second purpose?

I checked https://www.baeldung.com/lombok-custom-annotation to duplicate all the classes to cover both points in real time, but Java code generation looks really as a headache comparing to byte code updates.

Regards,

Oleksii

[raphw]

Yes, you would likely want to use AgentBuilder and a Java agent for this. That way, you can rewrite your code on the fly and collect input to methods.

[druzhynin-oleksii]

Like here: https://gist.github.com/raphw/34c0e2fffe2ee7b4f02f ?

[raphw]

That's an example of the API, yes.

[druzhynin-oleksii]

Hi Raphael.

I am just wondering why there is no good library for code modification before compilation. lombok can add only methods, but I didn't find how to make a syntactic sub-class using this.

Alex

[raphw]

There is JavaPoet which I personally like, but source code is way less structured what makes it much harder. Also, class file manipulation is more universal as it can target all JVM languages.

[druzhynin-oleksii]

But JavaPoet doesn't allow to modify existing classes.