RFR: 8229517: Support for optional asynchronous/buffered logging [v17]

[Xin Liu]

On Fri, 21 May 2021 09:43:36 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Xin Liu has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update according to reviewer's feedback.
>
> src/hotspot/share/logging/logFileOutput.cpp line 312:
> 
>> 310:   if (aio_writer != nullptr) {
>> 311:     aio_writer->enqueue(*this, decorations, msg);
>> 312:     return -1;
> 
> Any difference between returning 0 and -1 here? Could you add some comments if any?

This is interesting! Thanks for the comment. 
I take a look at logFileStreamOuptut.cpp again, `LogFileStreamOutput::write` returns -1 when it runs into some errors. 

I feel it's more appropriate to return 0 here.  The value suggests that 'succeed but the written bytes is unknown.'
so far,  it doesn't matter because nobody reads this return value.

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PR: https://git.openjdk.java.net/jdk/pull/3135