ClassFileTransformer.transform is not called when class is redefined

[Mugenor]

Hi
I'm trying to implement a plugin for HotSwapAgent and noticed that the method annotated with @OnClassLoadEvent(classNameRegexp = ".*", events = {LoadEvent.REDEFINE}) is not called when I'm trying to hotswap any class.
After some debugging process I found out that HotswapTransformer.transform (subclass of ClassFileTransformer) is not called for the class I tried to hotswap.
That is why I think that the problem is in VM, but let me know if I'm wrong, please.

JVM I'm using:

openjdk 17.0.5 2022-10-18
OpenJDK Runtime Environment JBR-17.0.5+1-653.14-nomod (build 17.0.5+1-b653.14)
OpenJDK 64-Bit Server VM JBR-17.0.5+1-653.14-nomod (build 17.0.5+1-b653.14, mixed mode)

HotSwapAgent version: 1.4.2-SNAPSHOT
OS: MacOS

[skybber]

I've tried a junit test from the owb-plugin and the method HotswapTransformer.transform is called correctly. Even I'm using HA+jbr17 on daily basis, so it must work. Is your plugin registered in HA-core correctly ?

[Mugenor]

Yes, I think it's registered correctly. It's initialised, listeners with LoadEvent.DEFINE event type are called correctly.

I'll provide some context:
I'm implementing a plugin for MyBatis to be able to refresh queries written in annotations.
I found out that method annotated with @OnClassLoadEvent(classNameRegexp = ".*", events = {LoadEvent.REDEFINE}) is actually called when I'm updating a query in annotation in my mapper, but I receive proxy class instead of interface itself (not sure if it's intended or not).
If I stop in debugger in the redefine listener method, I can see that ReloadJavaProxyCommand initiated redefinition of this proxy class via call of PluginManager.hotswap. And as far as I see PluginManager.hotswap is used in the junit tests.
So, probably that's the reason, why tests are working.
But if I try to redefine any other class the same listener is not called, but I expect it to be called.

I can try to create and share small project with my plugin if it helps.

P.S.: I'm not sure why ProxyPlugin is actually called since it's using pretty similar @OnClassLoadEvent annotation content

[skybber]

Dcevm redefines all classes extended from redefined class, that's the reason why you see the proxy class. ProxyPlugin redefines (rebuilds) Proxy classes (java proxy, cglib) in second step - after base class is redefined and after some timeout.
May be you can create a small project and I'll look on it.

[Mugenor]

mybatis-plugin-reproduction.zip
I attached the zip file with a demo project.
When I'm trying to redefine org.example.MyBatisMapper I receive event about it in org.example.hotswapplugin.NewMyBatisPlugin#onMapperInterfaceReload, but here I receive not an Interface, but a proxy class.
And when I'm trying to redefine org.example.MyService class, I don't receive an event regarding it.
And JVM is started with those parameters:

<<JDK-PATH>>/bin/java -agentlib:jdwp=transport=dt_socket,address=127.0.0.1:51312,suspend=y,server=n -XX:-MaxFDLimit --add-opens=java.base/sun.nio.ch=ALL-UNNAMED --add-opens=java.base/sun.security.action=ALL-UNNAMED -XX:+AllowEnhancedClassRedefinition -XX:HotswapAgent=external -javaagent:<<JDK-PATH>/lib/hotswap/hotswap-agent.jar=disablePlugin=JdkPlugin,disablePlugin=Logback,disablePlugin=WatchResources,disablePlugin=Idea,disablePlugin=Hibernate,disablePlugin=Hibernate3JPA,disablePlugin=Hibernate3,disablePlugin=Jersey1,disablePlugin=Jersey2,disablePlugin=Jetty,disablePlugin=Tomcat,disablePlugin=ZK,disablePlugin=MyFaces,disablePlugin=Mojarra,disablePlugin=Omnifaces,disablePlugin=ELResolver,disablePlugin=WildFlyELResolver,disablePlugin=OsgiEquinox,disablePlugin=Owb,disablePlugin=WebObjects,disablePlugin=Weld,disablePlugin=JBossModules,disablePlugin=ResteasyRegistry,disablePlugin=Deltaspike,disablePlugin=GlassFish,disablePlugin=Weblogic,disablePlugin=Vaadin,disablePlugin=Wicket,disablePlugin=CxfJAXRS,disablePlugin=FreeMarker,disablePlugin=Undertow,disablePlugin=MyBatis,disablePlugin=IBatis,disablePlugin=Spring

Thank you in advance!

[skybber]

May be the problem is in debugger that does not stop in the method when redefinition is triggered from debugger itself.

[Mugenor]

I added log statement to NewMyBatisPlugin#onMapperInterfaceReload to test your theory and can confirm it.
Thank you for pointing to the right direction.

So, is it a bug or a feature of debugger? And is there a workaround for this?