hg: panama/panama/jdk: Summary: push of version-2 prototype of Arrays2.0. Work remains, comment is requested.

[David Chase]

On 2014-10-07, at 9:35 PM, John Rose <john.r.rose at oracle.com> wrote:
> On Oct 7, 2014, at 5:59 PM, Samuel Audet <samuel.audet at gmail.com> wrote:
> 
>> Is panama-dev going to be the place where most of the discussions about Arrays2.0 take place? Or is this part of some other project?
> 
> I like to think of Panama as consisting of three major chunks of work:
> FFI, data layouts, and Arrays 2.0.
> 
> I gave an early and rough prospectus of the Arrays 2.0 work at
> the 2012 JVM Language Summit [1] and Karl Taylor and I talked
> more generally about flattened data structures this year[2].
> 
> [1]: http://cr.openjdk.java.net/~jrose/pres/201207-Arrays-2.pdf
> [2]: http://cr.openjdk.java.net/~jrose/pres/201407-FlattenedData.pdf

Note that there’s a reasonable-sized chunk of that Arrays2.0 talk that I have not
yet addressed — I have focused on multiple (well, 2 — and based on that, I am not
sure what the best plan for N > 2 is) dimensions, long addressing, bulk operations,
performance, and extensibility.

I *think* I have a plan for volatile, I think I have a plan for soft-read-only,
and I’m thinking about what the locking/concurrency world should look like.

Arrays embedded into objects, I have not yet looked into (except as part of a layout prototype),
I think that is a completely different sort of work (VM hacking, not library hacking — unless we do
it in Layout).  And I’m not going near the notation till I think I have the mechanisms all working reliably.

And it’s useful feedback to hear “I love the idea of bulk operations with built-in
fork/join and blocking” or “I really really need the ability to lock ranges of an array”
or “volatile access to array elements is very important to me”.

David