[foreign-memaccess+abi] RFR: 8296417: Make memory session a pure lifetime abstraction

[Maurizio Cimadamore]

On Fri, 4 Nov 2022 17:14:56 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> Add description

src/java.base/share/classes/java/lang/foreign/SegmentAllocator.java line 349:

> 347: 
> 348:     /**
> 349:      * Returns a segment allocator which responds to allocation requests by returning consecutive slices

Note: `newNativeArena` is now gone, and replaced with a more general "slicing allocator". The reason I did this was two-fold: the arena factory seemed to be fairly specific, and not very useful to build upon (slicing allocator greatly improve on that aspect). The second problem is the name: now that we have a toplevel Arena, I think having an arena allocator factory here would be too confusing. I don't think the loss in functionality is significant (newNativeArena can be trivially implemented in terms of a slicing allocator), but if we really need it, we could always add another Arena subclass (e.g. SlicingArena which does more or less what the old allocator did.

src/java.base/share/classes/jdk/internal/foreign/GlobalSession.java line 10:

> 8:  * Acquiring and or releasing a memory session similarly does nothing.
> 9:  */
> 10: final class GlobalSession extends MemorySessionImpl {

I've decided to split this (and implicit sessions) up, for better clarity

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PR: https://git.openjdk.org/panama-foreign/pull/750