com.netflix.servo.publish.MemoryMetricObserver Maven / Gradle / Ivy
/**
* Copyright 2013 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.publish;
import com.netflix.servo.Metric;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* Keeps the last N observations in-memory.
*/
public final class MemoryMetricObserver extends BaseMetricObserver {
private static final int DEFAULT_N = 10;
private final List[] observations;
private int next;
/**
* Creates a new instance that keeps 10 copies in memory.
*/
public MemoryMetricObserver() {
this("unamed observer", DEFAULT_N);
}
/**
* Creates a new instance that keeps {@code num} copies in memory.
*/
@SuppressWarnings("unchecked")
public MemoryMetricObserver(String name, int num) {
super(name);
observations = (List[]) new List[num];
next = 0;
}
/**
* {@inheritDoc}
*/
public void updateImpl(List metrics) {
observations[next] = metrics;
next = (next + 1) % observations.length;
}
/**
* Returns the current set of observations.
*/
public List> getObservations() {
List> builder = new ArrayList<>();
int pos = next;
for (List ignored : observations) {
if (observations[pos] != null) {
builder.add(observations[pos]);
}
pos = (pos + 1) % observations.length;
}
return Collections.unmodifiableList(builder);
}
}