Draft JEP on enhanced volatiles

[Brian Goetz]

> can you be a little more specific and provide the way
> foo.volatile.compareAndSet is compiled with this example:

Hey, the JEP isn't even out of draft yet!  Stop asking hard questions.

The current strawman, though, is to expose direct (CP-ready) MH forms 
(Lookup API / constant pool format TBD) for field get/set with fence, 
array element get/set with fence, field CAS, and array element CAS. 
Then the static compiler translates

    foo.volatile.cAS(n,m)

as

    LDC #MH[lookupFieldCASer(foo)]
    aload n
    aload m
    invokevirtual "invokeExact"

> class Linked {
>    volatile Node head;
>
>    public void add(String element) {
>      for(;;) {
>         Node oldHead = head.volatile.get();
>         Node newNode = new Node(element, oldHead);
>         if (head.volatile.compareAndSet(oldHead, newNode)) {
>           return;
>         }
>      }
>    }
> }
>
> I will be very happy to see how you solve the different issues because
> i've also spent some times thinking on how the .volatile syntax can be
> implemented:
>    - what is the signature of the method compareAndSet, and how you
> fight the generics erasure ?
>    - how do you remove the extra-level of indirection if head is a
> VolatileXXX,
>      because accessing to the value is this.head.payload and not
> this.head ?
>    - what LinkedClass.class.getDeclaredField("head").getType() returns ?
>
> regards,
> Rémi
>