Package io.opentelemetry.api.metrics

Interface DoubleSumObserver

  • All Superinterfaces:
    AsynchronousInstrument, Instrument
    @ThreadSafe
public interface DoubleSumObserver
extends AsynchronousInstrument
    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.setUpdater(
 //         new DoubleSumObserver.Callback<DoubleResult>() {
 //          @Override
 //           public void update(DoubleResult result) {
 //             // Get system cpu usage
 //             result.observe(cpuIdle, "state", "idle");
 //             result.observe(cpuUser, "state", "user");
 //           }
 //         });
 //   }
 // }