[Jscheme-user] Re: [Beanshell-users] Interrupting Interpreter Code Request

[Ken A. <kan...@bb...>]

My experience with JScheme is that calling a method to check if you've been interrupted is too costly.  So i esentially do
  if (INTERRUPTABLE) interruptCheck();

interruptCheck() looks like:
  /** Maybe interrupt this thread of execution. **/
  public static void interruptCheck() {
    if (INTERRUPTABLE && Thread.currentThread().interrupted()) {
      INTERRUPTABLE = false;
      throw new JschemeThrowable("Execution was interrupted.");
    }
  }

To interrupt a thread you call the static method:
  /** Interrupt execution on thread <tt>t</tt>. **/
  public static void interrupt (Thread t) {
    INTERRUPTABLE = true;
    t.interrupt();
  }
You may need something different in BeanShell.

We put the INTERRUPTABLE check in the main evaluator loop, at function calls, and in 14 other places for built in procedures - while loops for things like appending or mapping over lists which can be long.  But you can get along with just the check in the evaluator to start with.

k
At 04:20 PM 3/1/2004 -0600, Pat wrote:
>On Mon, Mar 01, 2004 at 02:09:38PM -0800, Shankar Unni wrote:
>> 
>> That might not work reliably either. Consider (for the sake of form):
>> 
>>   while (true) {
>>      try {
>>         while (true) ;
>>      } catch (Exception e) {}
>>   }
>> 
>> Now *that*'s practically uninterruptible, unless you catch it in the tiny
>> windows outside the try block.
>
>Yah, that's what I meant by adding the hooks to our looping control structures
>as well as the main loop.  There are only a few places necessary to cover all
>of those cases, I think...
>
>I'm speaking of script code of course... If Java code does that we're hosed ;)
>
>
>Pat
>
>
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