io.opentelemetry.metrics

Interface DoubleUpDownSumObserver

All Superinterfaces:

AsynchronousInstrument<DoubleUpDownSumObserver.ResultDoubleUpDownSumObserver>, Instrument

@ThreadSafe
public interface DoubleUpDownSumObserver
extends AsynchronousInstrument<DoubleUpDownSumObserver.ResultDoubleUpDownSumObserver>

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.getMeterRegistry().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<ResultDoubleUpDownSumObserver>() {
          {@literal @}Override
           public void update(ResultDoubleUpDownSumObserver result) {
             // Get system memory usage
             result.observe(memoryUsed, "state", "used");
             result.observe(memoryFree, "state", "free");
           }
         });
   }
 }
 

Since:

0.1.0

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	DoubleUpDownSumObserver.Builder Builder class for DoubleUpDownSumObserver.
static interface	DoubleUpDownSumObserver.ResultDoubleUpDownSumObserver The result for the Callback.

Nested classes/interfaces inherited from interface io.opentelemetry.metrics.AsynchronousInstrument

AsynchronousInstrument.Callback<R>

Method Summary

Modifier and Type	Method and Description
void	setCallback(AsynchronousInstrument.Callback<DoubleUpDownSumObserver.ResultDoubleUpDownSumObserver> callback) Sets a callback that gets executed every collection interval.

Method Detail

setCallback

void setCallback(AsynchronousInstrument.Callback<DoubleUpDownSumObserver.ResultDoubleUpDownSumObserver> callback)

Description copied from interface: AsynchronousInstrument

Sets a callback that gets executed every collection interval.

Evaluation is deferred until needed, if this AsynchronousInstrument metric is not exported then it will never be called.

Specified by:

setCallback in interface AsynchronousInstrument<DoubleUpDownSumObserver.ResultDoubleUpDownSumObserver>

Parameters:

callback - the callback to be executed before export.