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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.statsd;
import io.micrometer.core.instrument.AbstractMeter;
import io.micrometer.core.instrument.Gauge;
import io.micrometer.core.instrument.util.MeterEquivalence;
import io.micrometer.core.lang.Nullable;
import org.reactivestreams.Subscriber;
import java.lang.ref.WeakReference;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.ToDoubleFunction;
public class StatsdGauge extends AbstractMeter implements Gauge, StatsdPollable {
private final StatsdLineBuilder lineBuilder;
private final Subscriber subscriber;
private final WeakReference ref;
private final ToDoubleFunction value;
private final AtomicReference lastValue = new AtomicReference<>(Double.NaN);
private final boolean alwaysPublish;
private volatile boolean shutdown = false;
StatsdGauge(Id id, StatsdLineBuilder lineBuilder, Subscriber subscriber, @Nullable T obj, ToDoubleFunction value, boolean alwaysPublish) {
super(id);
this.lineBuilder = lineBuilder;
this.subscriber = subscriber;
this.ref = new WeakReference<>(obj);
this.value = value;
this.alwaysPublish = alwaysPublish;
}
@Override
public double value() {
T obj = ref.get();
return obj != null ? value.applyAsDouble(ref.get()) : Double.NaN;
}
@Override
public void poll() {
double val = value();
if (!shutdown && Double.isFinite(val) && (alwaysPublish || lastValue.getAndSet(val) != val)) {
subscriber.onNext(lineBuilder.gauge(val));
}
}
@SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
@Override
public boolean equals(Object o) {
return MeterEquivalence.equals(this, o);
}
@Override
public int hashCode() {
return MeterEquivalence.hashCode(this);
}
void shutdown() {
this.shutdown = true;
}
}