io.micrometer.core.instrument.composite.CompositeGauge Maven / Gradle / Ivy
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/**
* Copyright 2017 VMware, 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
*
* https://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 io.micrometer.core.instrument.composite;
import io.micrometer.core.instrument.Gauge;
import io.micrometer.core.instrument.Meter;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.noop.NoopGauge;
import io.micrometer.core.lang.Nullable;
import java.lang.ref.WeakReference;
import java.util.function.ToDoubleFunction;
class CompositeGauge extends AbstractCompositeMeter implements Gauge {
private final WeakReference ref;
private final ToDoubleFunction f;
CompositeGauge(Meter.Id id, @Nullable T obj, ToDoubleFunction f) {
super(id);
ref = new WeakReference<>(obj);
this.f = f;
}
@Override
public double value() {
return firstChild().value();
}
@Override
Gauge newNoopMeter() {
return new NoopGauge(getId());
}
@Override
Gauge registerNewMeter(MeterRegistry registry) {
final T obj = ref.get();
if (obj == null) {
return null;
}
return Gauge.builder(getId().getName(), obj, f)
.tags(getId().getTagsAsIterable())
.description(getId().getDescription())
.baseUnit(getId().getBaseUnit())
.register(registry);
}
}