Re: 'instrumenting' arrays

Using stack frames, you can probably rule out some cases where it's clearly
coming from a simple array  (e.g. it was just constructed in this same
method) but I think this will be a rare scenario.  If an array is passed in
as a method argument, for example, you would have to backtrack to all of its
callers and so on.  In simple cases (not that they're simple to solve) you
can figure it out but ultimately you're looking at the halting problem.

I think you're going to more or least have to treat them all as if they
might be your transactional array... invoke some method that decides if they
are or not and do the right thing.

On Tue, Mar 9, 2010 at 2:04 PM, Peter Veentjer <[email protected]>wrote:

> I'm writing an STM called Multiverse
> http://multiverse.codehaus.org
>
> One of the things I want to add to one of the next releases is support
> for transactional arrays. I already figured out how to deal with the
> array itself;
> if an transactional object has a field of type array of type X, I
> upgrade the type of that field to: array of type transactional
> reference of type X. This is
> peanuts. I already got a prototype TransactionalArray working that
> doesn't rely on instrumentation and lazily fills the array with
> transactional references.
> And I also got transactional references for primitives that reduce the
> amount of boxing/unboxing.
>
> The big problem is with the instrumentation of methods because it is
> hard to figure out if the bytecode that accesses an array is touching
> a normal array
> or a transactional one. With GET_FIELD/PUT_FIELD this isn't a problem
> because the instrumentation can determine based on the type of the
> field owner
> if something extra needs to be done. But in this case the context
> matters and not the type.
>
> So has someone experience with 'instrumenting' arrays?
>
>
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