Charles,
Contexts have complicated lifetime. If you just curious how weak
handles work, you'd better play with simpler objects.
Handle goes near death state when it found out it references weakly
reachable object. You're callback is never invoked as v8 retains the
context (it's a current context) and hence strongly reachable from
inside v8. Value is base type, so everything is an instance of Value.
Please note that you have a bug in your code: your weak callback must
either dispose the handle passed or revive it.
And, just in case, most of objects are created and returned back in
Local handles. Those handles live as long as handle scope to which
they belong and retain the object. Thus the code:
HandleScope hs;
Persistent p = Persistent::New(Object::New());
p.MakeWeak(...)
// Force GC
will never trigger weak callback as l is alive and it retains the
object. The right way:
Persistent p;
{
HandleScope hs;
p = Persistent::New(Object::New());
}
p.MakeWeak(...)
// Force GC
hth and yours,
anton.
On Fri, Apr 8, 2011 at 1:59 AM, Charles Lowell <[email protected]> wrote:
> Hi,
>
> I'm having trouble understanding when a Persistent handle is
> considered "Near Death", and when exactly a weak reference callback is
> invoked. Consider the following code:
>
> https://gist.github.com/908831
>
> It appears that the WeakReference Callback is never invoked.
>
> I guess my questions are
>
> 1) Why is it never considered near death? given that there is only one
> reference to it which is weak.
>
> 2) why isn't the PrintlnWeakReferenceCallback ever invoked?
>
> 3) WeakReferenceCallbacks take a Persistent<Value> as a parameter.
> What if, as in this case, the object is not a Value?
>
> cheers,
> Charles
>
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>
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