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More Thread Checker

Today was pretty much a repeat from yesterday: I fixed (or at least worked on) another DrJava bug [1] and made improvements to my dynamic thread checker. Unfortunately, the bug fix did not make it into our new new stable release [2] anymore. I also couldn’t reproduce the “Unsupported major.minor version” error, but that may even be a good thing.

I was a little bit late to our research meeting, but when I talked about the thread checker, Corky agreed that annotations on superclasses or methods in superclasses should be considered in subclasses as well. He also said I could go ahead and use DrJava as test codebase. We didn’t talk very much, but when I mentioned the warnings that should be raised when a subclass has an annotation but a superclass does not, he suggested that perhaps an annotation should only be allowed where a method is first introduced, and not in a subclass or implementing class.

We both agreed that this might not be practical, though: Often programmers implement Standard Java API interfaces, like ActionListener, and then they would not be able to annotate those implementing classes.

I still need to do a little more testing and write unit tests, but I did write the code tonight that checks superclasses and interfaces for annotations as well. The code for subtyping warnings is there too, but it generates a lot of warnings… More than may be useful. They currently look like this:

ThreadCheckTest has @NotRunBy thread name 'foo' but java.lang.Object does not
ThreadCheckTest3 has @OnlyRunBy thread name 'main2' but java.lang.Object does not
ThreadCheckTest4.run()V has @NotRunBy thread name 'childclass-method2' but ThreadCheckTest4SuperClass.run()V does not

I think I may want to exclude java.lang.Object from this. And perhaps even more.

This sort of brings up the topic of instrumenting library code. There are probably a lot of AWT/Swing methods that should only be executed by the event thread, for example, but how do I instrument them? The source has been released, but I don’t think I actually want to compile it.

So what I have in mind now is an external text or XML file that just contains location-annotation pairs so the programmer can tell the instrumentor to attach a @OnlyRunBy(eventThread=true) to java.swing.text.Document or a @NotRunBy(threadName="main") to java.lang.Runtime.exit(I)V.

I’m excited to see the thread checker grow and to apply it to DrJava. I may actually have some statistical and benchmarking data soon. All right, it’s nearly 5 AM again, and I think I should try to sleep (but not oversleep) again.

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