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

[Alan Bateman]

On Tue, 6 Jun 2023 19:39:31 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

src/java.base/share/classes/java/net/Socket.java line 43:

> 41: import java.util.Collections;
> 42: 
> 43: import jdk.internal.event.SocketWriteEvent;

You'll probably want to clean up the imports to avoid having import of jdk.internal classes in two places.

src/java.base/share/classes/java/net/Socket.java line 1109:

> 1107:                 nbytes = read0(b, off, len);
> 1108:             } finally {
> 1109:                 SocketReadEvent.checkForCommit(start, nbytes, parent.getRemoteSocketAddress(), parent.getSoTimeout());

So if read throws, this will commit a jdk.SocketReadEvent with size 0, maybe this will change later to include the exception?

src/java.base/share/classes/java/net/Socket.java line 1114:

> 1112:         }
> 1113: 
> 1114:         private int read0(byte[] b, int off, int len) throws IOException {

Can you rename this to implRead?

src/java.base/share/classes/java/net/Socket.java line 1215:

> 1213:                 return;
> 1214:             }
> 1215:             int bytesWritten = 0;

Is bytesWritten needed?

src/java.base/share/classes/java/net/Socket.java line 1226:

> 1224:         }
> 1225: 
> 1226:         public void write0(byte[] b, int off, int len) throws IOException {

Can you change this to be private and rename to implWrite?

src/java.base/share/classes/sun/nio/ch/SocketChannelImpl.java line 421:

> 419:     }
> 420: 
> 421:     private int read0(ByteBuffer buf) throws IOException {

Can you rename this to implRead too?

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PR Review Comment: https://git.openjdk.org/jdk/pull/14342#discussion_r1236731407
PR Review Comment: https://git.openjdk.org/jdk/pull/14342#discussion_r1237226982
PR Review Comment: https://git.openjdk.org/jdk/pull/14342#discussion_r1236719052
PR Review Comment: https://git.openjdk.org/jdk/pull/14342#discussion_r1236719603
PR Review Comment: https://git.openjdk.org/jdk/pull/14342#discussion_r1236719373
PR Review Comment: https://git.openjdk.org/jdk/pull/14342#discussion_r1237227861