8245121: (bf) XBuffer.put(Xbuffer src) can give unexpected result when storage overlaps

[Brian Burkhalter]

> On May 28, 2020, at 5:21 PM, Paul Sandoz <paul.sandoz at oracle.com> wrote:
> 
> Here’s a tip, rather than creating a fixed size array upfront:
> 
> - create a List<Object[]> to add argument list combinations to
> - add with args.add(new Object[] {proxy})
> - at the end do args.toArray(Object[][]::new)

Cool - thanks!

> For:
> 
>  281             List<BufferProxy> proxies1 = getProxies(type);
>  282             List<BufferProxy> proxies2 = getProxies(type);
>  283             for (BufferProxy proxy1 : proxies1) {
>  284                 for (BufferProxy proxy2 : proxies2) {
>  285                     data[index][0] = proxy1;
>  286                     data[index++][1] = proxy2;
>  287                 }
>  288             }
> 
> Can you reuse proxy1 since the list is not modified and the proxy is stateless w.r.t. Buffers? Is it necessary to test when proxy1 == proxy2 i.e. the diagonal?

Good point. Yes I think it can be re-used as there is no relevant state. I don’t think it’s necessary to check for proxy1 == proxy2: we want to test the case where both are the same type, kind, and order.

> It’s useful to try the streams approach as an exercise, I can imagine some people might find nested flatMaps a little jarring. The nested loops are fine here.

The updated version is at

http://cr.openjdk.java.net/~bpb/8245121/webrev.04/

It keeps getting shorter!

Thanks,

Brian
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