RFR (14) 8235837: Memory access API refinements

[Maurizio Cimadamore]

New revision:

http://cr.openjdk.java.net/~mcimadamore/8235837_v2

delta from previous iteration:

http://cr.openjdk.java.net/~mcimadamore/8235837_v2_delta

javadoc

http://cr.openjdk.java.net/~mcimadamore/8235837_v2_javadoc

specdiff

http://cr.openjdk.java.net/~mcimadamore/8235837_v2_specdiff/overview-summary.html

Cheers
Maurizio

On 09/01/2020 14:36, Maurizio Cimadamore wrote:
> Hi,
> following the JEP 370 code review and CSR, certain comments that have 
> not been addressed have been added to the tracker issue:
>
> https://bugs.openjdk.java.net/browse/JDK-8235837
>
> For further evaluation. After some discussion in the Panama channel 
> (see [1] and [2]), the Panama team has come to the following conclusions:
>
> * the MemoryAddress::offset(long) method should be renamed to 
> MemoryAddress::addOffset(long)
> * the MemorySegment::isAccessible() predicate should be dropped and 
> replaced with the MemorySegment::ownerThread() accessor
> * a new predicate should be added to MemoryLayout, namely 
> MemoryLayout::hasSize() to allow clients to establish as to whether a 
> layout contains some unsized parts
> * a new method should be added to SequenceLayout, namely 
> SequenceLayout::withElementCount, to create a new sequence layout with 
> new element count
> * 2 new helper methods should be added to MemoryLayout, namely:
>    - MemoryLayout::map - to allow transformation of a layout into a 
> new layout (by replacing the sub-layout at given path with a new layout)
>    - MemoryLayout::select - to allow selection of a sub-layout given a 
> layout path
>
> Overall, we think this set of change strikes a good compromise between 
> usability, readability and minimality.
>
> The javadoc for the layout path-accepting methods (both old and new 
> ones) has been significantly refactored and improved - and the 
> toplevel javadoc section on layout paths has been enhanced to cover 
> all the concepts. The implementation for these methods has also been 
> consolidated greatly, which revealed subtle bugs in the old 
> implementation which have now been rectified (new tests have been added).
>
> Webrev is available here:
>
> http://cr.openjdk.java.net/~mcimadamore/8235837/
>
> Specdiff for changes here:
>
> http://cr.openjdk.java.net/~mcimadamore/8235837_specdiff/overview-summary.html 
>
>
> A draft CSR for this issue is available here (I will finalize once the 
> review converges on the API changes):
>
> https://bugs.openjdk.java.net/browse/JDK-8236853
>
> I plan to push this to JDK 14 under the late enhancement process [3].
>
> Cheers
> Maurizio
>
> [1] - 
> https://mail.openjdk.java.net/pipermail/panama-dev/2019-December/006873.html
> [2] - 
> https://mail.openjdk.java.net/pipermail/panama-dev/2019-December/006885.html
> [3] - https://openjdk.java.net/jeps/3#Late-Enhancement-Request-Process
>
>
>
>
>