Thanks for implementing this enhancement Erik. I think it'll prove to be
popular given the functionality available in JFR recordings. I'd agree
with Alan's comment that the Event class could be documented better to
indicate its purpose.
I'm already using this enhancement to implement some new events in the
JDK security libraries. I hope to get a review started real soon on that
front.
Regards,
Sean.
On 19/06/18 03:06, Erik Gahlin wrote:
Hi,
Could I have a review of an enhancement that will make it possible to
add JFR events to java.base, and possibly other modules in the JDK,
without a compile time dependency on jdk.jfr.
Bug:
https://bugs.openjdk.java.net/browse/JDK-8203629
Webrev:
http://cr.openjdk.java.net/~egahlin/8203629.0
Testing:
Tests in test/jdk/jdk/jfr
The functionality is a prerequisite for an upcoming enhancement that
will add JFR events to the security libraries.
In short, jdk.jfr.Event (located in jdk.jfr) extends
jdk.internal.event.Event (located in java.base). Metadata for events,
such as labels and descriptions, are added using a mirror event class
located in jdk.jfr module. If the fields of the mirror class and the
event class don't match an InternalError is thrown.
To illustrate how the mechanism can be used, see the following example
(not meant to be checked in).
http://cr.openjdk.java.net/~egahlin/8203629.example
Since the implementation of jdk.internal.event.Event is empty, the JIT
will typically eliminate all traces of JFR functionality unless Flight
Recorder is enabled.
Thanks
Erik
