RFR: 8261407: ReflectionFactory.checkInitted() is not thread-safe [v2]

[David Holmes]

On Sun, 19 Dec 2021 06:51:45 GMT, liach <duke at openjdk.java.net> wrote:

>> Upon review of [8261407](https://bugs.openjdk.java.net/browse/JDK-8261407), by design, duplicate initialization of ReflectionFactory should be safe as it performs side-effect-free property read actions, and the suggesting of making the `initted` field volatile cannot prevent concurrent initialization either; however, having `initted == true` published without the other fields' values is a possibility, which this patch addresses.
>> 
>> This simulates what's done in `CallSite`'s constructor for `ConstantCallSite`. Please feel free to point out the problems with this patch, as I am relatively inexperienced in this field of fences and there are relatively less available documents. (Thanks to https://shipilev.net/blog/2014/on-the-fence-with-dependencies/)
>
> liach has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Just use volatile directly to ensure read order

As Alan notes there is no need for explicit initialization to the default value, so a volatile write can be saved. Otherwise this seems to address the problem of safe publication.

Thanks,
David

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/6889