RFR: 8292989: Avoid dynamic memory in AsyncLogWriter [v2]

[Xin Liu]

On Wed, 31 Aug 2022 17:53:24 GMT, Xin Liu <xliu at openjdk.org> wrote:

>> src/hotspot/share/logging/logAsyncWriter.hpp line 98:
>> 
>>> 96:     bool push_back(const AsyncLogMessage& msg);
>>> 97: 
>>> 98:     // for testing-only!
>> 
>> We typically allow test fixture classes to be declared `friend`s to the classes they test. This allows you to move testing functions to the testing code.
>
> make sense!

I made `AsyncLogWriter::throttle_buffers' private.

I don't think it's necessary to declare `friend class AsyncLogWriter` here in class Buffer. Buffer is a private nested class and we can't construct it outside, so I think it's okay to leave `set_capacity` public here.

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

PR: https://git.openjdk.org/jdk/pull/10092