[jmm-dev] VarHandle.safepoint() methods

[Doug Lea]

On 01/05/2017 07:55 AM, Doug Lea wrote:

> A complementary approach would be to allow programmers
> to manually insert safepoint checks, such that the JVM would
> not insert one if already there.
>
> As in  (for some field x, VH X, and local r:)
>     r = X.get(this);
>     ...
>     if (VarHandles.checkPointed()) // returns true if safepoint
>         r = X.getAcquire(this);
>

Or, more plausibly, using epoch-based indicators:

     r = X.get(this);
     e = varHandles.getEpoch();
     ...
     if (VarHandles.checkPointedEpoch() != e) // true if safepoint
         r = X.getAcquire(this);

-Doug