How can I make external methods interruptable?

Question

The Problem

I\'m running multiple invocations of some external method via an ExecutorService. I would like to be able to interrupt these methods, but unfortunately the

Answer 1

You wrote:

Another option I've tried is to mark myMethod() and similar methods with a special "Interruptable" annotation and then use AspectJ (which I am admittedly a newbie at) for catching all method invocations there - something like:

@Before("call(* *.*(..)) && withincode(@Interruptable * *.*(..))")
public void checkInterrupt(JoinPoint thisJoinPoint) {
    if (Thread.interrupted()) throw new ForcefulInterruption();
}

But withincode isn't recursive to methods called by the matching methods, so I would have to edit this annotation into the external code.

The AspectJ idea is good, but you need to

• use cflow() or cflowbelow() in order to recursively match a certain control flow (e.g. something like @Before("cflow(execution(@Interruptable * *(..)))")).
• make sure to also weave your external library, not just you own code. This can be done by either using binary weaving, instrumenting the JAR file's classes and re-packaging them into a new JAR file, or by applying LTW (load-time weaving) during application start-up (i.e. during class loading).

You might not even need your marker annotation if your external library has a package name you can pinpoint with within(). AspectJ is really powerful, and often there is more than one way to solve a problem. I would recommend using it because it was made for such endeavours as yours.