RFR: 8256156: JFR: Allow 'jfr' tool to show metadata without a recording

[Erik Gahlin]

On Fri, 8 Jan 2021 10:04:58 GMT, Yang Yi <github.com+5010047+kelthuzadx at openjdk.org> wrote:

>> Hi all,
>> 
>> May I please have a review for this minor patch?
>> 
>> It simplifies the use of subcommand `metadata` of jfr tool. Recording 
>> file is no longer mandatory, users can directly use `jfr metadata` to 
>> output JDK builtin meta information. As JDK-8256156 mentioned, it also 
>> supports events and categories filters:
>> $ jfr metadata 
>> $ jfr metadata recording.jfr # compatible
>> $ jfr metadata --events jdk.ThreadStart,jdk.ThreadEnd
>> $ jfr metadata --events jdk.ThreadStart,jdk.ThreadEnd recording.jfr
>> $ jfr metadata --categories GC,Detailed
>> $ jfr metadata --categories GC,Detailed recording.jfr
>
> @egahlin  Hi Erik, I have updated my patch according to your review comments.

You need to add a CSR as well to the bug report, where the syntax etc. is described.

https://bugs.openjdk.java.net/browse/JDK-8205517

Do you have a JIRA account?

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PR: https://git.openjdk.java.net/jdk/pull/1904