Let me paraphrase to make sure I understand you.
You want to call observeInstructionCount() externally as the method which
will interrupt the thread?
If I understood that right then all you want to do is create another method
in the "MyContext" factory which will set an interrupt flag that
observeInstructionCount will monitor.
To extend the example given:
// Custom Context to store execution time.
private static class MyContext extends Context
{
long startTime;
boolean interruptFlag = false;
}
public synchronized interruptScript(){
interruptFlag = true;
}
// Override observeInstructionCount(Context, int)
protected void observeInstructionCount(Context cx, int
instructionCount)
{
//All the other stuff from the example...
if(interruptFlag == true) throw new Error();
}
observeInstructionConnt() is only being called by the javascript engine
which in turn monitors for the exception to be thrown and propagates it
through the script (the Error's can't be caught by the script, hence it
propagates right through and out of the script context).
Let me know if I'm off base with my understanding.
David
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Patrick
Lightbody
Sent: Thursday, February 19, 2009 9:26 AM
To: Attila Szegedi
Cc: David Parks; [email protected]
Subject: Re: Stopping JavaScript Evaluation
Duh - thanks! I was starting to do that last night, though instead of
a subclass I was looking at getThreadLocal() and putThreadLocal() as a
way to get a "Stoppable" object that had the flag in it.
I'd rather do it on the Context directly (less indirection), but am
curious about one thing: It doesn't appear a subclass (MyContext) can
set the internal factory field. This will cause an error in many of
the default methods of Context. For example:
protected void observeInstructionCount(int instructionCount)
{
ContextFactory f = getFactory();
f.observeInstructionCount(this, instructionCount);
}
Because the "factory" field is private and is only set in a
package-protected constructor, and because getFactory() is
public+final, there is no way for me to extend Context while still
passing in a reference to the factory. In the example JavaDocs, this
looks like it's skipped entirely.
It may work for me, since I'll be overriding observeInstructionCount
and not calling super, but it worries me a bit. There are other
methods that also depend on the factory being not-null:
public boolean hasFeature(int featureIndex)
{
ContextFactory f = getFactory();
return f.hasFeature(this, featureIndex);
}
public static void exit()
{
Object helper = VMBridge.instance.getThreadContextHelper();
Context cx = VMBridge.instance.getContext(helper);
if (cx == null) {
throw new IllegalStateException(
"Calling Context.exit without previous Context.enter");
}
if (cx.enterCount < 1) Kit.codeBug();
if (--cx.enterCount == 0) {
VMBridge.instance.setContext(helper, null);
cx.factory.onContextReleased(cx);
}
}
Any ideas?
Patrick
On Thu, Feb 19, 2009 at 1:57 AM, Attila Szegedi <[email protected]> wrote:
> On 2009.02.19., at 7:49, David Parks wrote:
>
>> Can you not add the stop flag check to the observeInstructionCount
>> callback
>> method? That would be the most straight forward way to stop the script
and
>> really take very few lines of code to implement. Can you explain why this
>> wouldn't work in your case? If you're concerned with finding a reference
>> to
>> the stop check flag you can always extend Context and add your own
>> reference
>> to whatever object contains the check you need to perform as nearly
>> demonstrated in this example:
>>
>>
>>
http://www.mozilla.org/rhino/apidocs/org/mozilla/javascript/ContextFactory.h
>> tml
>
> Hm... I'm thinking I might update that example a bit - throw a
> java.lang.ThreadDeath specifically in place of generic java.lang. Error.
>
> Attila.
>
>> David
>
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> dev-tech-js-engine-rhino mailing list
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