@ThreadSafe public interface DoubleValueObserver extends AsynchronousInstrument<AsynchronousInstrument.DoubleResult>
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 DoubleValueObserver cpuObserver =
meter.
.doubleValueObserverBuilder("cpu_temperature")
.setDescription("System CPU temperature")
.setUnit("ms")
.build();
void init() {
cpuObserver.setCallback(
new DoubleValueObserver.Callback<DoubleResult>() {
{@literal @}Override
public void update(DoubleResult result) {
// Get system cpu temperature
result.observe(cpuTemperature);
}
});
}
}
Modifier and Type | Interface and Description |
---|---|
static interface |
DoubleValueObserver.Builder
Builder class for
DoubleValueObserver . |
AsynchronousInstrument.Callback<R extends AsynchronousInstrument.Result>, AsynchronousInstrument.DoubleResult, AsynchronousInstrument.LongResult, AsynchronousInstrument.Result
Modifier and Type | Method and Description |
---|---|
void |
setCallback(AsynchronousInstrument.Callback<AsynchronousInstrument.DoubleResult> callback)
Sets a callback that gets executed every collection interval.
|
void setCallback(AsynchronousInstrument.Callback<AsynchronousInstrument.DoubleResult> callback)
AsynchronousInstrument
Evaluation is deferred until needed, if this AsynchronousInstrument
metric is not
exported then it will never be called.
setCallback
in interface AsynchronousInstrument<AsynchronousInstrument.DoubleResult>
callback
- the callback to be executed before export.