RFR (XS): CR 8004330: Add missing Unsafe entry points for addAndGet() family (original) (raw)

Aleksey Shipilev aleksey.shipilev at oracle.com
Wed Jan 9 11:04:57 UTC 2013

Thanks, David.

On 01/09/2013 02:55 PM, David Holmes wrote:

Not sure where this is now but FYI you needed two CRs for this: one for hotspot and one for the JDK. They have different target versions (hs25 vs 8) and depending on the path you use to integrate could end up in different builds - hence distinct CRs for accurate tracking purposes.

Too late, since these are already committed? I can submit another CR if we need that.

I have a concern that the Long versions of these methods may be used directly without there being any check for supportscx8

I actually have the question about this. What is the usual pattern for using AtomicLong.VM_SUPPORTS_LONG_CAS? AtomicLong seems to use Unsafe directly without the checks. AtomicLongFieldUpdater does the checks. Something is fishy about this whole thing.

I think this one tries to explain something, but I fail to grasp the intent:

/**
 * Records whether the underlying JVM supports lockless
 * compareAndSwap for longs. While the Unsafe.compareAndSwapLong
 * method works in either case, some constructions should be
 * handled at Java level to avoid locking user-visible locks.
 */
static final boolean VM_SUPPORTS_LONG_CAS = VMSupportsCS8();

Doug?

-Aleksey.

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