daimingzhi commented on issue #7440:
URL: https://github.com/apache/skywalking/issues/7440#issuecomment-897351911
> Because the delegate mechanism only supports to do once
I didn't fully grasp the meaning of this。but,I tested the byteBuddy API like
this
- code of agent
```java
public class ByteBuddyAgent {
public static void premain(String agentArgs, Instrumentation inst) {
// install first time
new AgentBuilder.Default()
.type(named("com.easy4coding.bytebuddy.Bar"))
.transform(new AgentBuilder.Transformer() {
@Override
public DynamicType.Builder transform(DynamicType.Builder
builder,
TypeDescription
typeDescription,
ClassLoader classloader,
JavaModule javaModule) {
return builder.method(named("m"))
.intercept(MethodDelegation.to(new
BarInterceptorFirst()));
}
}).installOn(inst);
// install second time
new AgentBuilder.Default()
.type(named("com.easy4coding.bytebuddy.Bar"))
.transform(new AgentBuilder.Transformer() {
@Override
public DynamicType.Builder transform(DynamicType.Builder
builder,
TypeDescription
typeDescription,
ClassLoader classloader,
JavaModule javaModule) {
return builder.method(named("m"))
.intercept(MethodDelegation.to(new
BarInterceptorSecond()));
}
}).installOn(inst);
}
}
public class BarInterceptorFirst {
@RuntimeType
public Object intercept(@This Object obj, @AllArguments Object[]
allArguments, @SuperCall Callable<?> zuper,
@Origin Method method) {
System.out.println("before method first");
Object ret = null;
try {
ret = zuper.call();
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("after method first");
return ret;
}
}
public class BarInterceptorSecond {
@RuntimeType
public Object intercept(@This Object obj, @AllArguments Object[]
allArguments, @SuperCall Callable<?> zuper,
@Origin Method method) {
System.out.println("before method Second");
Object ret = null;
try {
ret = zuper.call();
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("after method Second");
return ret;
}
}
```
- testDemo
```java
public class DuplicateInstallDemo {
public static void main(String[] args) {
new Bar().m();
}
}
```
The program output is as follows：
```shell
before method 2
before method
method named m invoked
after method
after method 2
```
What puzzles me most about the first one is, how do I group pluginDefine?
What I did in my company was adjust the directory structure of the project
and extend the AgentClassLoader。
like this:
But, this way is not suitable for skywaling obviously。
> You missed one important port, `EnhancedInstance#dynamicField`, which has
only one value.
I'm not really familiar with this piece of logic now.I will spend more time
learning about it,Also, I might have to learn more about ByteBuddy
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