RFR: 8256156: JFR: Allow 'jfr' tool to show metadata without a recording [v14]

[Erik Gahlin]

On Sat, 6 Mar 2021 11:45:26 GMT, Yi Yang <yyang 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
>
> Yi Yang has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR.

Looks good. 

I still think the name of the test method should be called testWildcard() instead of testWildcardAndAcronym() since it is not testing acronyms, i.e using "GC" instead of "GarbageCollection", which is fine, but the name of the method should be appropriate.

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

Marked as reviewed by egahlin (Reviewer).

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