[crac] RFR: RCU Lock - RW lock with very lightweight read- and heavyweight write-locking [v2]

[Dan Heidinga]

On Wed, 12 Apr 2023 12:27:14 GMT, Radim Vansa <duke at openjdk.org> wrote:

>> This implementation is suitable for uses where the write-locking happens very rarely (if at all), as in the case of CRaC checkpoint, and we don't want to slow down regular access to the protected resource.
>
> Radim Vansa has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reuse MethodHandles.lookup()
>   
>   Co-authored-by: Dan Heidinga <heidinga at redhat.com>

src/java.base/share/native/libjava/RCULock.c line 70:

> 68:     }
> 69:     for (int i = 0; i < num; ++i) {
> 70:         jobject el = (*env)->GetObjectArrayElement(env, methods, i);

I think for correctness, this needs to be followed by an exception check

if ((*env)->ExceptionOccurred(env)) {
   free_up_to(c_methods, i);
   // exception already pending
   return;
}

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PR Review Comment: https://git.openjdk.org/crac/pull/58#discussion_r1164062255