[foreign-memaccess] [Rev 03] RFR: Move "owner" field and thread-confinement checks to MemoryScope

[Jorn Vernee]

On Fri, 15 May 2020 13:10:06 GMT, Peter Levart <plevart at openjdk.org> wrote:

>> Now MemoryScope is simplified, I re-based this change and am opening this PR on top. Currently MemorySegment is
>> encapsulating thread-confinement logic and state (owner field) while MemoryScope is encapsulating temporal-confinement
>> logic and state. But the interplay between the two must be very carefully caried out (for example, close() or dup() on
>> child scopes may only be called in owner thread). By moving the thread-confinement logic and state to MemoryScope, I
>> think we get better encapsulation as all MemoryScope methods become "safe" - some can still be called in owner thread
>> only, but failing to do so throws IllegalSateException instead of exhibiting undefined behavior.
>
> Peter Levart has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix confined root MemoryScope.close() - confinement check is required

src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/MemoryScope.java line 192:

> 191:             checkAliveConfined(this);
> 192:         }
> 193:     }

This changes the behavior we had before in AbstractMemorySegmentImpl::checkValidState. We should still do the liveness
check even if there is no owner.

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PR: https://git.openjdk.java.net/panama-foreign/pull/167