Package io.opentelemetry.api.metrics

Interface LongValueObserver

  • All Superinterfaces:
    AsynchronousInstrument<AsynchronousInstrument.LongResult>, Instrument
    @ThreadSafe
public interface LongValueObserver
extends AsynchronousInstrument<AsynchronousInstrument.LongResult>
    ValueObserver is the asynchronous instrument corresponding to ValueRecorder, used to capture values that are treated as individual observations, recorded with the observe(value) method.

    A ValueObserver is a good choice in situations where a measurement is expensive to compute, such that it would be wasteful to compute on every request.

    Example: 

    
 class YourClass {

   private static final Meter meter = OpenTelemetry.getMeterProvider().get("my_library_name");
   private static final LongValueObserver cpuObserver =
       meter.
           .longValueObserverBuilder("cpu_fan_speed")
           .setDescription("System CPU fan speed")
           .setUnit("ms")
           .build();

   void init() {
     cpuObserver.setCallback(
         new LongValueObserver.Callback<LongResult>() {
          {@literal @}Override
           public void update(LongResult result) {
             // Get system cpu fan speed
             result.observe(cpuFanSpeed);
           }
         });
   }
 }