com.netflix.spectator.api.ObjectGauge Maven / Gradle / Ivy
/**
* Copyright 2015 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.netflix.spectator.api;
import java.util.Collections;
import java.util.function.ToDoubleFunction;
/**
* Gauge that is defined by executing a {@link ToDoubleFunction} on an object.
*/
class ObjectGauge extends AbstractMeter implements Gauge {
private final ToDoubleFunction f;
/**
* Create a gauge that samples the provided number for the value.
*
* @param clock
* Clock used for accessing the current time.
* @param id
* Identifier for the gauge.
* @param obj
* {@link Object} used to access the value.
* @param f
* Function that is applied on the value for the number. The operation {@code f.apply(obj)}
* should be thread-safe.
*/
ObjectGauge(Clock clock, Id id, T obj, ToDoubleFunction f) {
super(clock, id, obj);
this.f = f;
}
@Override public Iterable measure() {
return Collections.singleton(new Measurement(id, clock.wallTime(), value()));
}
@Override public double value() {
final T obj = ref.get();
return (obj == null) ? Double.NaN : f.applyAsDouble(obj);
}
}