RFR 8075926: Add a sun.management.JMXConnectorServer perf counter to track its state

[Staffan Larsen]

> On 18 maj 2015, at 10:25, Jaroslav Bachorik <jaroslav.bachorik at oracle.com> wrote:
> 
> On 18.5.2015 10:21, Staffan Larsen wrote:
>> Looks good, but why is the reverseBytes needed?
>> 
>> 60             this.bb.asLongBuffer().put(Long.reverseBytes(l));
> 
> For some reason Perf.createLong(...) will create bytebuffer with the HILO byte order reversed when compared to how long is usually represented.

I think you should set the order() of the ByteBuffer before you create the LongBuffer. See the code in sun.misc.PerfCounter:

private PerfCounter(String name, int type) {
    this.name = name;
    ByteBuffer bb = perf.createLong(name, type, U_None, 0L);
    bb.order(ByteOrder.nativeOrder());
    this.lb = bb.asLongBuffer();
}

/Staffan

> 
> -JB-
> 
>> 
>> Thanks,
>> /Staffan
>> 
>>> On 13 maj 2015, at 17:39, Jaroslav Bachorik <jaroslav.bachorik at oracle.com> wrote:
>>> 
>>> Please, review the following change
>>> 
>>> Issue : https://bugs.openjdk.java.net/browse/JDK-8075926
>>> Webrev: http://cr.openjdk.java.net/~jbachorik/8075926/webrev.00
>>> 
>>> The sun.management.JMXConnectorServer.<version>.<key> perf counters are not updated when the remote management agent is stopped.
>>> 
>>> The perf counters show stale data and mislead the users.
>>> 
>>> Since it is not possible to 'un-export' perf counters we need an additional counter tracking the version of the related perf counters in use.
>>> 
>>> In the current implementation each start of the remote management agent will export a new set of the related perf counters (sun.management.JMXConnectorServer.<version>.<key>) with the <version> part increased by one. The first remote management agent start will use 0 as its version.
>>> 
>>> The new counter 'sun.management.JMXConnectorServer.remote' will have value of -1 if the remote management is stopped and non-negative number corresponding to the version of the related perf counters in use.
>>> 
>>> Thanks,
>>> 
>>> -JB-
>> 
>