Package io.opentelemetry.api.metrics

Interface DoubleSumObserver

  • All Superinterfaces:
    AsynchronousInstrument<AsynchronousInstrument.DoubleResult>, Instrument
    @ThreadSafe
public interface DoubleSumObserver
extends AsynchronousInstrument<AsynchronousInstrument.DoubleResult>
    SumObserver is the asynchronous instrument corresponding to Counter, used to capture a monotonic sum with Observe(sum).

    "Sum" appears in the name to remind that it is used to capture sums directly. Use a SumObserver to capture any value that starts at zero and rises throughout the process lifetime and never falls.

    A SumObserver 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 DoubleSumObserver cpuObserver =
       meter.
           .doubleSumObserverBuilder("cpu_time")
           .setDescription("System CPU usage")
           .setUnit("ms")
           .build();

   void init() {
     cpuObserver.setCallback(
         new DoubleSumObserver.Callback<DoubleResult>() {
          {@literal @}Override
           public void update(DoubleResult result) {
             // Get system cpu usage
             result.observe(cpuIdle, "state", "idle");
             result.observe(cpuUser, "state", "user");
           }
         });
   }
 }