Re: Patch: embedded window extension

[Michael Koch <konqueror at gmx dot de>]

Am Freitag, 23. Juli 2004 14:26 schrieb Eric Blake:
> Your approach looks okay to me; you solved my initial concern about
> correctness.  But I still have 2 comments.
>
> First, I am not sure whether setAccessible(true) is visible by
> anyone else using reflection; should you be caching the
> pre-existing accessible value on entry and restoring it before
> existing the priveleged action?  This is more of a general question
> I have about reflection - is getDeclaredField() allowed to return
> the same Field instance to more than one caller, and if so, is
> there a race condition where when one thread has set the Field as
> accessible inside a privileged action, another thread without
> security privileges can use that same Field with the temporary
> elevation in accessibility even though that thread can't change the
> accessibility?  Or is getDeclaredField() required to return a
> different instance to every caller?  On the other hand, there are
> also security checks for getDeclaredField, so a security manager
> can enforce that only privileged actions can access the Field
> instance in the first place, allowing getDeclaredField to return
> the same instance to all allowed callers.

I'm no expert in reflection. In fact I'm using it first time directly. 
Perhaps someone other can help ?

> Second, how often is this method called?  If it is called
> frequently, I would consider creating a cached version of the
> anonymous PrivilegedAction, rather than creating and destroying one
> for every invocation.  If it is rarely called, then caching is
> probably not worth the effort, and your code is fine as is.

This method should be called only once. I think there is no need for 
caching.


Michael