java scripting with mozilla rhino and memory management problem

Question

I'm building an javascript api that will call some java objects using mozilla rhino.

Everything is good and nice, however I want to avoid unlimited looping that could slow my java application.

for example (in javascript):

while(true) doSomething(); // doSomthing will call a method in java

In modern browsers after a certain time an error appears telling the script is making the application to run slow, and if I want to continue and stop script.

I want to implement this on my java application if it's possible, but I don't know how. The only solution I can think about is to count the number of methods are being called per second, and if it's a huge number to stop the script. DO you have any other ideas?

Answer 1

Counting the method calls won't work for code that doesn't call any methods, like:

while (true) {
    i++;
}

I think what you want is observeInstructionCount(). Also see the discussion here - some of the stuff that they're discussing looks a little iffy, but it might help you.

Answer 2

If you can make the application multithreaded you could spawn a new thread handling each call from javascript. at the start of the thread you record the start time, and create some timeout logic to go with that.

    public void doJavaScript() {
      final long start = System.currentTimeMillis();
      final long timeout = 1000;
      new Thread(){
          @Override
          public void run() {
             while ((start + timeout) < System.currentTimeMillis()) {
                ... do work ...
             }
          }
      }.start();
    }