RFR: 8255883: Avoid multiple GeneratedMethodAccessor for same NativeMethod… [v5]

[Aleksey Shipilev]

On Wed, 11 Nov 2020 05:38:08 GMT, Hui Shi <hshi at openjdk.org> wrote:

>> …AccessorImpl object
>> 
>> We met real problem when using protobuf with option optimized for code size, detail in JBS https://bugs.openjdk.java.net/browse/JDK-8255883
>> 
>> Optimize solution is adding a new boolean field to detect concurrent method accessor generation in same NativeMethodAccessorImpl object, only one thread is allowed to generate accessor, other threads still invoke in jni way until parent's delegator is updated from NativeMethodAccessorImpl  to generated accessor.
>> 
>> In common case, extra overhead is an atomic operation, compared with method accessor generate, this cost is trivial.
>
> Hui Shi has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR.

Looks okay (as far as low-level code goes) to me. Others need to ack too.

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1070