add asm instrument

[jaehong-kim]

#2016

[jiaqifeng]

@jaehong-kim
I tried to read the code while it was really many! I just want to know can I instrument all sub-class of a specified base class?
I contributed the hystrix plugin. In hystrix, user inherit from HystrixCommand and implement the abstract method run(). This run() method should be intercepted but pinpoint previous release could only inspect a class you know its class name. All I want is to intercept run() method of all sub-class of HystrixCommand.
Can this PR support what I want? If not, will you consider support it in the future?

[jaehong-kim]

Not yet supported.
Performance is still difficult to check for inheritance between classes.

But someday we will support it.

[jiaqifeng]

@jaehong-kim
So you use ASM to replace Javassist just to improve performance? I have seen another APM using ASM and support what I want. While search in inheritance really will slow the boot time a lot. But you know, most apps boot time exceed a half minutes, it is not acceptable to double the boot time. ^-^