Re: org.apache.sling.commons.metrics.MetricsService not supporting gauge type

[Allen Liu]

Hi Robert,
Thanks for the link. I have tried the Gauge support approach explained in the 
Sling ticket you provided. I can't seem to get it to work to meet my use case. 
Maybe I don't understand the approach completely. 
It says to register the Gauge as a service instead of using the metricService 
like the other 4 metrics (i.e. counter, timer etc)

I created a gauge interface: 

import org.apache.sling.commons.metrics.Gauge;

public interface GaugeMonitor extends Gauge<Integer> {

    void setValue(int val);

}

A gauge implementation:
public class GaugeImpl implements GaugeMonitor {

    private volatile int value;

    @Override
    public void setValue(int val){
        value = val;
    }

    @Override
    public Integer getValue() {
        return value;
    }
}

Then I created a function in my monitoring service to register gauge as a 
service:
    @Reference(target = "(name=sling)")
    private MetricRegistry registry;

    public GaugeMonitor gauge(String name){
        GaugeMonitor m =  (GaugeMonitor) registry.getGauges().get(name);
        if(m != null){
            return m;
        }
        GaugeMonitor gauge = new GaugeImpl();
        Dictionary<String, String> properties = new Hashtable<String, String>();
        properties.put(Gauge.NAME, name);
        bundleContext.registerService(Gauge.class, gauge, properties);
        return gauge;
    }

The first gauge works fine but if I want to reuse the gauge in another bundle 
by calling monitorService.gauge("sameGaugeName"), I get a ClassCastException.

Do you know if there is a way to reuse the gauge without checking the 
metricRegistry? 

Thanks

Allen 

On 5/27/20, 2:34 AM, "Robert Munteanu" <romb...@apache.org> wrote:

    On Wed, 2020-05-27 at 00:07 +0000, Allen Liu wrote:
    > Hi Robert,
    > Thanks a lot for the info. I was also using MetricRegistry to
    > register the gauge metrics. I thought there was a way to add the
    > gauge metric using metricsService.
    > After looking into the implementation of metricsService, it seems to
    > be not trivial to add the gauge registration in the metricsService. 
    > 
    > So, I will keep my implementation as it is to register gauge metrics
    > using MetricRegistry.


    While looking futher, it seems that there is Gague support, please see

      
https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fissues.apache.org%2Fjira%2Fbrowse%2FSLING-5966&amp;data=02%7C01%7Calliu%40adobe.com%7C776ef6f7866a435a194408d802211bb9%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637261688512048503&amp;sdata=Ksw5ueFzSazsjHOy7zuG0Rf4QFoY39fRc%2FRZUgbx%2Bq8%3D&amp;reserved=0

    Can you give this a try and let me know if it works for you?

    Thanks,
    Robert