com.netflix.servo.monitor.BasicGauge Maven / Gradle / Ivy
/*
* Copyright 2011-2018 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.servo.monitor;
import com.netflix.servo.SpectatorContext;
import com.netflix.servo.annotations.DataSourceType;
import com.netflix.servo.tag.TagList;
import com.netflix.servo.util.Throwables;
import java.util.concurrent.Callable;
/**
* A gauge implementation that invokes a specified callable to get the current value.
*/
public final class BasicGauge extends AbstractMonitor
implements Gauge, SpectatorMonitor {
private final MonitorConfig baseConfig;
private final Callable function;
/**
* Creates a new instance of the gauge.
*
* @param config configuration for this monitor
* @param function a function used to fetch the value on demand
*/
public BasicGauge(MonitorConfig config, Callable function) {
super(config.withAdditionalTag(DataSourceType.GAUGE));
this.baseConfig = config;
this.function = function;
}
/**
* {@inheritDoc}
*/
@Override
public T getValue(int pollerIndex) {
try {
return function.call();
} catch (Exception e) {
throw Throwables.propagate(e);
}
}
/**
* {@inheritDoc}
*/
@Override
public void initializeSpectator(TagList tags) {
SpectatorContext.polledGauge(baseConfig)
.monitorValue(this, m -> m.getValue(0).doubleValue());
}
/**
* {@inheritDoc}
*/
@Override
public boolean equals(Object obj) {
if (obj == null || !(obj instanceof BasicGauge)) {
return false;
}
BasicGauge m = (BasicGauge) obj;
return config.equals(m.getConfig()) && function.equals(m.function);
}
/**
* {@inheritDoc}
*/
@Override
public int hashCode() {
int result = config.hashCode();
result = 31 * result + function.hashCode();
return result;
}
/**
* {@inheritDoc}
*/
@Override
public String toString() {
return "BasicGauge{config=" + config + ", function=" + function + '}';
}
}