Package io.opentelemetry.api.metrics

Interface DoubleUpDownSumObserver

  • All Superinterfaces:
    AsynchronousInstrument<AsynchronousInstrument.DoubleResult>, Instrument
    @ThreadSafe
public interface DoubleUpDownSumObserver
extends AsynchronousInstrument<AsynchronousInstrument.DoubleResult>
    UpDownSumObserver is the asynchronous instrument corresponding to UpDownCounter, used to capture a non-monotonic count with Observe(sum).

    "Sum" appears in the name to remind that it is used to capture sums directly. Use a UpDownSumObserver to capture any value that starts at zero and rises or falls throughout the process lifetime.

    A UpDownSumObserver 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 DoubleUpDownSumObserver memoryObserver =
       meter.
           .doubleUpDownSumObserverBuilder("memory_usage")
           .setDescription("System memory usage")
           .setUnit("by")
           .build();

   void init() {
     memoryObserver.setCallback(
         new DoubleUpDownSumObserver.Callback<DoubleResult>() {
          {@literal @}Override
           public void update(DoubleResult result) {
             // Get system memory usage
             result.observe(memoryUsed, "state", "used");
             result.observe(memoryFree, "state", "free");
           }
         });
   }
 }