RFR: 8271186: Add UL option to replace newline char [v4]

[Yasumasa Suenaga]

On Tue, 24 Aug 2021 18:01:51 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Yasumasa Suenaga has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:
>> 
>>  - Update UL help message and manpage
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8271186
>>  - Fix test on Windows
>>  - Implement as foldmultilines
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8271186
>>  - add inclusion of os.hpp
>>  - 8271186: Add UL option to replace newline char
>
> src/hotspot/share/logging/logFileOutput.cpp line 204:
> 
>> 202:       success = LogFileStreamOutput::initialize(pos, errstream);
>> 203:       *equals_pos = '\0';
>> 204:       if (!success) {
> 
> I think the code can be simplified by parsing the value here:
> 
> bool fold_multilines = ....;
> LogFileStreamOutput::set_fold_multilines(foldmultilines);

`foldmultilines` is a parameter which should be applied in initialization. `LogOutput` and extended classes of it look like to have a rule to apply initialization parameter at `initialize()`.
We can simplify the code as you said if we can apply `foldmultiline` for `LogFileStreamOutput` at `LogFileOutput::initialize()`, but I concern it breaks the semantics for UL implementation.

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PR: https://git.openjdk.java.net/jdk/pull/4885