[foreign-preview] RFR: 8281855: Rename ResourceScope to MemorySession [v7]

[Maurizio Cimadamore]

On Wed, 16 Feb 2022 21:30:31 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> Maurizio Cimadamore has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:
>> 
>>  - Merge branch 'foreign-preview' into session_preview
>>  - Fix spurious reference to ResourceScopeImpl after merge
>>  - Merge branch 'foreign-preview' into session_preview
>>  - Address review comments
>>    * replace spurious usages of `scope` in direct buffer template
>>  - Update src/java.base/share/classes/java/lang/ClassLoader.java
>>    
>>    Co-authored-by: Paul Sandoz <paul.d.sandoz at googlemail.com>
>>  - Update src/java.base/share/classes/java/nio/Direct-X-Buffer.java.template
>>    
>>    Co-authored-by: Paul Sandoz <paul.d.sandoz at googlemail.com>
>>  - Fix more spurious usages of ResourceScope
>>  - Fix whitespaces
>>  - Merge branch 'foreign-preview' into session_preview
>>  - Fix reference to ResourceScope in javadoc
>>  - ... and 2 more: https://git.openjdk.java.net/panama-foreign/compare/14b6c7b4...bee07da5
>
> src/java.base/share/classes/jdk/internal/foreign/abi/UpcallStubs.java line 59:
> 
>> 57:             }
>> 58:         });
>> 59:         return new NativeSymbolImpl("upcall:" + Long.toHexString(entry), MemoryAddress.ofLong(entry), ((MemorySessionImpl)session));
> 
> If I understand correctly, this doesn't use `Scoped.toSessionImpl` since the session doesn't need to be closed in this case?

No: `NativeSymbolImpl` wants a true, closeable MemorySessionImpl. Then, if you look at that class, its `session` method will return a non closeable view of that session. The `toSessionImpl` happens in `AbstractCLinker::upcallStub`.

> test/jdk/java/foreign/TestRestricted.java line 69:
> 
>> 67:         var mh = MethodHandles.lookup().findStatic(MemorySegment.class, "ofAddress",
>> 68:             MethodType.methodType(MemorySegment.class, MemoryAddress.class, long.class, MemorySession.class));
>> 69:         var seg = (MemorySegment)mh.invoke(MemoryAddress.NULL, 4000L, MemorySession.global());
> 
> Why is this relaxed to invoke?

Not sure - probably just a refactoring accident

-------------

PR: https://git.openjdk.java.net/panama-foreign/pull/641