RFR: JDK-8266536: Provide a variant of os::iso8601_time which works with arbitrary timestamps [v5]

[Yasumasa Suenaga]

On Fri, 7 May 2021 07:07:54 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> We have os::iso8601_time(), which gives an ISO8601 timestamp of the current time. It would be very useful to have a second variant which can be fed an arbitrary numerical timestamp.
>> 
>> This is useful in the context of making asynchronous UL logging cheaper (see JDK-8229517)
>> 
>> This patch provides an additional API: 
>> `char* os::iso8601_time(jlong milliseconds_since_19700101, char* buffer, size_t buffer_length, bool utc);`
>> alongside the existing
>> `char* os::iso8601_time(char* buffer, size_t buffer_length, bool utc);`
>> and implements the latter using the former. Not much code added.
>> 
>> In addition, it adds a regression gtest for these APIs.
>> 
>> Please ignore the harfbuzz change, its a build fix needed for older gcc, will be removed before final push.
>> 
>> Testing: GHA, manual gtests, SAP nightlies on all our platforms.
>> 
>> Thanks, Thomas
>
> Thomas Stuefe has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - remove stray edit
>  - Yasumasa-feedback-2

Thank you for fixing it! It still looks good.

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Marked as reviewed by ysuenaga (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3869