RFR: 8291714: Implement a Multi-Reader Single-Writer mutex for Hotspot [v5]

[David Holmes]

On Tue, 30 Aug 2022 00:11:16 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Johan Sjölén has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Review comments
>
> src/hotspot/share/utilities/readWriteLock.hpp line 91:
> 
>> 89:   ~ReadWriteLock() = default;
>> 90: 
>> 91:   void write_lock(Thread* current = Thread::current_or_null());
> 
> I'm not seeing the motivation for allowing current to be null with these latest changes.

To be clear, you will only ever get a null if someone passes it in explicitly as Thread::current_or_null() should never be able to return null in the contexts you would use this RWL.

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PR: https://git.openjdk.org/jdk/pull/9838