--- Kris Schneider <[EMAIL PROTECTED]> wrote:
> I don't think synchronization is the answer for this one. The general
> problem is
> that while one thread is running through the enumeration returned from
> ServletContext.getAttributeNames, another thread adds or removes an
> application
> scoped attribute. Even if you successfully lock down this method, other
> methods
> are still free to mess with the collection of application scope
> attributes.
The problem in this case is that it's putting an attribute into the
context for the first time which is a structural modification. Updating
existing context attributes is not a structural modification so we just
need to worry about the initialization in this method.
David
> It
> just seems like the creation and caching of the prefixes array should be
> done at
> startup instead of on-demand. Then, this method would just become
> something like:
>
> public static String[] getModulePrefixes(ServletContext context) {
> return (String[])context.getAttribute(Globals.PREFIXES_KEY);
> }
>
> Quoting David Graham <[EMAIL PROTECTED]>:
>
> > I'm looking at fixes for
> > http://nagoya.apache.org/bugzilla/show_bug.cgi?id=21091
> >
> > 1. Synchronize the entire RequestUtils.getModulePrefixes() method.
> >
> > OR
> >
> > 2. The first thing the method does is checks for prefixes in the
> context
> >
> > String[] prefixes = (String[]) context.getAttribute(PREFIXES_KEY);
> > if (prefixes != null) {
> > return prefixes;
> > }
> >
> > What if the rest of the code below that was inside a
> > synchronized(RequestUtils.class) {} block and the first thing that
> block
> > does is perform the check again?
> >
> > Is this considered double checked locking? It's slightly different
> than
> > the examples I've seen because we would be looking up the value in the
> > context instead of testing a member variable for null.
> >
> > I think solution 2 will work but I want to make sure.
> >
> > Thanks,
> > David
> >
> > __________________________________
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>
> --
> Kris Schneider <mailto:[EMAIL PROTECTED]>
> D.O.Tech <http://www.dotech.com/>
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