Need option for actuator+dropwizard timers for short timings

[tdalsing-pivotal]

When using dropwizard with spring boot actuator the timers are in milliseconds. For timings that are less than 1 ms the values are always 0 since the output is an integer and the value is truncated. Please change the output to a floating point value.

Test code:

@RestController
public class DWController {

    private MetricRegistry registry;

    @Autowired
    public DWController(MetricRegistry registry) {
        this.registry = registry;
    }

    @RequestMapping("/foo/{count}")
    public String foo(@PathVariable("count") int count) {
        Timer timer = registry.timer("fooTimer");
        Timer.Context ctx = timer.time();

        // do something that will take < 1 millisecond
        for (int i = 0; i < count; ++i) {
            double d = Math.pow(i, 10);
        }

        long t = ctx.stop();
        return "" + t;
    }
}

Exercising the code:

curl http://localhost:8080/foo/10

several times results in:

{
  "mem": 362154,
  "mem.free": 279813,
  "processors": 4,
  "instance.uptime": 30543,
  "uptime": 35343,
  "systemload.average": 3.80029296875,
  "heap.committed": 314368,
  "heap.init": 262144,
  "heap.used": 34554,
  "heap": 3728384,
  "nonheap.committed": 50048,
  "nonheap.init": 2496,
  "nonheap.used": 47743,
  "nonheap": 0,
  "threads.peak": 22,
  "threads.daemon": 20,
  "threads.totalStarted": 26,
  "threads": 22,
  "classes": 5977,
  "classes.loaded": 5977,
  "classes.unloaded": 0,
  "gc.ps_scavenge.count": 6,
  "gc.ps_scavenge.time": 83,
  "gc.ps_marksweep.count": 1,
  "gc.ps_marksweep.time": 46,
  "fooTimer.snapshot.median": 0,
  "gauge.response.foo.count": 3.0,
  "fooTimer.fiveMinuteRate": 0.605644105347075,
  "fooTimer.count": 17,
  "fooTimer.snapshot.75thPercentile": 0,
  "fooTimer.snapshot.999thPercentile": 0,
  "fooTimer.snapshot.max": 0,
  "fooTimer.snapshot.98thPercentile": 0,
  "fooTimer.fifteenMinuteRate": 0.6021061761967533,
  "counter.status.200.foo.count": 17,
  "fooTimer.snapshot.95thPercentile": 0,
  "fooTimer.snapshot.99thPercentile": 0,
  "fooTimer.snapshot.stdDev": 0,
  "fooTimer.meanRate": 0.6349273410338819,
  "fooTimer.oneMinuteRate": 0.6107670725235096,
  "fooTimer.snapshot.min": 0,
  "fooTimer.snapshot.mean": 0,
  "httpsessions.max": -1,
  "httpsessions.active": 0
}

[snicoll]

This has been superseded by the planned move to Micrometer-based metrics (#9970)