RFR: 8308995: Update Network IO JFR events to be static mirror events [v5]

[Daniel Fuchs]

On Thu, 7 Sep 2023 21:50:17 GMT, Tim Prinzing <tprinzing at openjdk.org> wrote:

>> The socket read/write JFR events currently use instrumentation of java.base code using templates in the jdk.jfr modules. This results in some java.base code residing in the jdk.jfr module which is undesirable.
>> 
>> JDK19 added static support for event classes. The old instrumentor classes should be replaced with mirror events using the static support.
>> 
>> In the java.base module:
>> Added two new events, jdk.internal.event.SocketReadEvent and jdk.internal.event.SocketWriteEvent.
>> java.net.Socket and sun.nio.ch.SocketChannelImpl were changed to make use of the new events.
>> 
>> In the jdk.jfr module:
>> jdk.jfr.events.SocketReadEvent and jdk.jfr.events.SocketWriteEvent were changed to be mirror events.
>> In the package jdk.jfr.internal.instrument, the classes SocketChannelImplInstrumentor, SocketInputStreamInstrumentor, and SocketOutputStreamInstrumentor were removed. The JDKEvents class was updated to reflect all of those changes.
>> 
>> The existing tests in test/jdk/jdk/jfr/event/io continue to pass with the new implementation:
>> Passed: jdk/jfr/event/io/TestSocketChannelEvents.java
>> Passed: jdk/jfr/event/io/TestSocketEvents.java
>> 
>> I added a micro benchmark which measures the overhead of handling the jfr socket events.
>> test/micro/org/openjdk/bench/java/net/SocketEventOverhead.java.
>> It needs access the jdk.internal.event package, which is done at runtime with annotations that add the extra arguments.
>> At compile time the build arguments had to be augmented in make/test/BuildMicrobenchmark.gmk
>
> Tim Prinzing has updated the pull request incrementally with one additional commit since the last revision:
> 
>   More changes from review:
>   
>   I didn't like the name of the helper method 'checkForCommit' because it
>   doesn't indicate that it might commit the event.  I also don't like
>   'commitEvent' because it might not.  Since JFR events are sort of like a
>   queue I went with a name from collections and called it 'offer' so using
>   it is something like 'SocketReadEvent.offer(...)' which seems like it
>   gets the idea across better.  Also improved the javadoc for it.
>   
>   Removed the comments about being instrumented by JFR in
>   Socket.SocketInputStream and Socket.SocketOutputStream.
>   
>   I went ahead and moved the event commiting out of the finally block so
>   that we don't emit events when the read/write did not actually happen.
>   The bugid JDK-8310979 will be used to determine if more should be done
>   in this area.
>   
>   The implRead and implWrite were moved up with the other support methods
>   for read/write.

LGTM. Are there existing that will help verify that the read events and write events are still emitted as expected? If not shouldn't we write some?

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PR Review: https://git.openjdk.org/jdk/pull/14342#pullrequestreview-1633551891