notes/pl/java/libfws/byte-code/bytebuddy/features/interceptor.txt

import net.bytebuddy.implementation.FixedValue;
import net.bytebuddy.implementation.MethodDelegation 
import net.bytebuddy.implementation.bind.annotation.Origin;
import net.bytebuddy.implementation.bind.annotation.RuntimeType;
import net.bytebuddy.implementation.bind.annotation.SuperCall;


import java.lang.reflect.Method;
import java.util.concurrent.Callable;


FixedValue.value("Hello Foo Redefined")


.intercept(MethodDelegation.to(new GreetingInterceptor()))

public class GeneralInterceptor {
  @RuntimeType
  public Object intercept(@AllArguments Object[] allArguments,
                          @Origin Method method) {
    // intercept any method of any signature
  }
}

public class TimingInterceptor {
  @RuntimeType
  public static Object intercept(@Origin Method method, 
                                 @SuperCall Callable<?> callable) {
    long start = System.currentTimeMillis();
    try {
      return callable.call();
    } finally {
      System.out.println(method + " took " + (System.currentTimeMillis() - start));
    }
  }
}

MethodCall
https://bytebuddy.net/javadoc/1.10.1/net/bytebuddy/implementation/MethodCall.html
https://www.programcreek.com/java-api-examples/?api=net.bytebuddy.implementation.MethodCall
https://github.com/raphw/byte-buddy/blob/master/byte-buddy-dep/src/test/java/net/bytebuddy/implementation/MethodCallTest.java
    MethodCall.infokeSelf().on...()

redefine problem
https://github.com/raphw/byte-buddy/issues/41
https://stackoverflow.com/questions/40774684/error-while-redefining-a-method-with-bytebuddy-class-redefinition-failed-atte
https://github.com/raphw/byte-buddy/issues/143
https://stackoverflow.com/questions/44935662/chain-transform-method-calls-with-bytebuddy
https://github.com/raphw/byte-buddy/issues/321
https://assets.ctfassets.net/oxjq45e8ilak/4EFaeFr4kZTjgJF2d3IvRW/9f8b66c722e62386ceb6316bee23473e/Rafael_Winterhalter_The_definite_guide_to_Java_agents.pdf
    disableClassFormatChanges()
https://github.com/raphw/byte-buddy/blob/master/byte-buddy-dep/src/test/java/net/bytebuddy/agent/builder/AgentBuilderDefaultApplicationTest.java
    !!!


... {
    public static String bar(Integer n, int k) {
        log.info("bar called");
        return "do bar n:" + n + ", k=" + k;
    }
    public static String baz(Integer n, int k) {
        return "do baz";
    }

    @Override
    public void run(String... args) throws Exception {
        log.info("app start");

        Method bar = App.class.getDeclaredMethod("bar", Integer.class, int.class);
        //Method baz = App.class.getDeclaredMethod("baz");

        ByteBuddyAgent.install();
        new ByteBuddy()
            .redefine(Simple.class)
            .method(named("tell"))
            //.intercept(MethodDelegation.to(new TimingInterceptor()))
            //.intercept(FixedValue.value("Hello Foo Redefined"))
            .intercept(
                MethodCall.invoke(bar)                 // call bar()...
                //.andThen(MethodCall.invoke(baz))  // ... .length()?
                .withAllArguments()
            )
            .make()
            .load(
                Simple.class.getClassLoader(), 
                ClassReloadingStrategy.fromInstalledAgent()
            );

        Simple s = new Simple();
        String ret = s.tell(1, 2);
        log.info("app finish: {}", ret);
    }
}