weld-invokedynamic

This code is a proof of concept for using InvokeDynamics vs proxy in Weld Framework

What is showed

This project contains tools to rewrite bytecode in class and replace call to injected field (annotated @Inject) by InvokeDynamic call

Pre-requisites to run this poc

You'll need a JDK 1.7 (tested with update 45). The code is not running under Java 8 right now due to API change in java.lang .invoke between java 7 and 8. You'll also need maven 3.x

Organisation of the project

The project 2 modules:

• weld-indy-agent: which contains all the bytecode instrumentation and java agent definition to add the invokedynamic calls
• weld-indy-impl: which contains CDI-aware invokedynamic boostrap code (to define indy call site) and example beans

To run the tests in weld-indy-impl, make sure that the first module (invoke dynamic Java agent) has been built.

Run the code

The code contains 2 CDI beans FirstBean and SecondBean both Application Scope (so proxified by Weld) and a test. SecondBean inject FirstBean and one of this method calls a FirstBean method that triggers an exception on purpose to show the exact stack trace of its call. The Arquillian test inject SecondBean and call triggers the FirstBean exception through a call to SecondBean method.

To see the first Effect of InvokeDynamic start by launching the code without InvokeDynamic instrumentation. You can this simply by issuing mvn -Pno-indy command (build and test will be launch by default). You'll see the following in your console :

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running org.jboss.weld.invokedynamic.WeldTest
avr. 23, 2014 6:02:42 PM org.jboss.weld.bootstrap.WeldStartup <clinit>
INFO: WELD-000900: 2.2.0 (SP1)
Contructing Second Bean
Service in SecondBean calling firstBean
Constructing First Bean
Working in firstBean
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 1.175 sec <<< FAILURE! - in org.jboss.weld.invokedynamic.WeldTest
testFirstBeanCall(org.jboss.weld.invokedynamic.WeldTest)  Time elapsed: 0.053 sec  <<< ERROR!
java.lang.RuntimeException: throwing exception on purpose
	at org.jboss.weld.test.FirstBean.doSomeWork(FirstBean.java:21)
	at org.jboss.weld.test.FirstBean$Proxy$_$$_WeldClientProxy.doSomeWork(Unknown Source)
	at org.jboss.weld.test.SecondBean.doSservice(SecondBean.java:19)
	at org.jboss.weld.test.SecondBean$Proxy$_$$_WeldClientProxy.doSservice(Unknown Source)
	at org.jboss.weld.invokedynamic.WeldTest.testFirstBeanCall(WeldTest.java:42)

You can see 2 WeldClientProxy in the stack trace and 5 step from exception to test

Now launch with InvokeDynamic by issuing mvn the result will be :

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
**** Starting Invoke Dynamic Agent ****
Running org.jboss.weld.invokedynamic.WeldTest
avr. 23, 2014 6:01:26 PM org.jboss.weld.bootstrap.WeldStartup <clinit>
INFO: WELD-000900: 2.2.0 (SP1)
*** InvokeDynamicBootstrap -> linking bean resolution for field: secondBean
$$$ Resolver called via InvokeDynamic -> Resolving injected bean in bean: org.jboss.weld.invokedynamic.WeldTest@7443f7a3 in field: secondBean
Contructing Second Bean
*** InvokeDynamicBootstrap -> linking method MethodHandle(SecondBean)void on bean: doSservice
Service in SecondBean calling firstBean
*** InvokeDynamicBootstrap -> linking bean resolution for field: bean
$$$ Resolver called via InvokeDynamic -> Resolving injected bean in bean: org.jboss.weld.test.SecondBean@1c81c2fa in field: bean
Constructing First Bean
*** InvokeDynamicBootstrap -> linking method MethodHandle(FirstBean)void on bean: doSomeWork
Working in firstBean
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 1.68 sec <<< FAILURE! - in org.jboss.weld.invokedynamic.WeldTest
testFirstBeanCall(org.jboss.weld.invokedynamic.WeldTest)  Time elapsed: 0.112 sec  <<< ERROR!
java.lang.RuntimeException: throwing exception on purpose
	at org.jboss.weld.test.FirstBean.doSomeWork(FirstBean.java:21)
	at org.jboss.weld.test.SecondBean.doSservice(SecondBean.java:19)
	at org.jboss.weld.invokedynamic.WeldTest.testFirstBeanCall(WeldTest.java:42)

No more WeldClientProxy and only 3 step from exception to test. Also note the runtime linking (line starting with ***) and the trace of the method resolving bean (line starting with $$$)

Check Bytecode

By default instrumentation occurs at class loading time so it's hard to see what was changed. You can use the indy-write profile (issue mvn -Pindy-write) to ask for instrumentation at compilation. You'll be able to check bytecode with javap -c or with your IDE if it provides bytecode viewing.

Going further

There are a lot of point that need to be enhanced in this firs Proof Of Concept. The main I can see are :

Better Resolution

This code is quite rudimentary regarding bean resolution. The method Bootstraper.resolveBean() should be enhanced by a Weld specialist to use cache and optimize resolution.

Better Injection Instrumentation

Instrumentation code only detect simple InjectionPoint by looking for @Inject annotation on field. We should add all other use case :

• Constructor and getter parameter injection
• Injection in producer parameter
• Instrumentation of Instance<> resolution

among others.

Use InvokeDynamic for AOP

One of the hard point : implement Interceptor spec and Decorator with InvokeDynamic. That will probably be the next step in this POC.