On 21/02/2014 7:20 AM, Paul Sandoz wrote:
On Feb 20, 2014, at 9:09 PM, David Holmes <david.hol...@oracle.com> wrote:
In practice, because there are also final fields in these instances
implementations will most likely perform a storestore barrier after
construction and prior to setting the reference to the created object.
Yes, that is what i was banking on.
That is how hotspot behaves, right?
Yes.
But, you are saying other VMs might not do so?
Right. A storestore at the end of construction is a simple and obvious
way to implement the final-field semantics, but there may be other ways.
The visibility guarantees for final fields extends only to those fields,
and objects accessed through them.
For illustrative purposes only: you could move all the lazy-initialized
fields into a separate State object, which is accessed via a final
field, and then they could be safely initialized and would not need to
be volatile.
David
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Paul.
That would make non-volatile appear to work, but it would not be guaranteed to do so and
the final-field "freeze" action only guarantees that unsafe publication will
see the correct value of the final fields (and for final references anything reachable
via that reference).
