com.arangodb.internal.QueueTimeMetricsImpl Maven / Gradle / Ivy
/*
* DISCLAIMER
*
* Copyright 2016 ArangoDB GmbH, Cologne, Germany
*
* 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.
*
* Copyright holder is ArangoDB GmbH, Cologne, Germany
*/
package com.arangodb.internal;
import com.arangodb.QueueTimeMetrics;
import com.arangodb.model.QueueTimeSample;
import java.util.Arrays;
/**
* @author Michele Rastelli
*/
public class QueueTimeMetricsImpl implements QueueTimeMetrics {
private final CircularFifoQueue samples;
public QueueTimeMetricsImpl(int queueSize) {
samples = new CircularFifoQueue(queueSize);
}
@Override
public QueueTimeSample[] getValues() {
return samples.getElements();
}
@Override
public double getAvg() {
return samples.getAvg();
}
void add(double value) {
add(new QueueTimeSample(System.currentTimeMillis(), value));
}
void add(QueueTimeSample value) {
samples.add(value);
}
void clear() {
samples.clear();
}
private static class CircularFifoQueue {
private final QueueTimeSample[] elements;
/**
* Capacity of the queue.
*/
private final int size;
/**
* Array index of the oldest queue element.
*/
private int start;
/**
* Amount of elements in the queue.
*/
private int count;
/**
* Sum of the values in the queue.
*/
private double sum;
CircularFifoQueue(final int size) {
elements = new QueueTimeSample[size];
this.size = elements.length;
clear();
}
/**
* @return the average of the values in the queue, 0.0 if the queue is empty.
*/
synchronized double getAvg() {
if (count == 0) return 0.0;
return sum / count;
}
synchronized void clear() {
start = 0;
count = 0;
sum = 0.0;
Arrays.fill(elements, null);
}
/**
* Adds the given element to this queue. If the queue is full, the least recently added
* element is replaced with the given one.
*
* @param element the element to add
*/
synchronized void add(final QueueTimeSample element) {
if (count < size) {
count++;
}
QueueTimeSample overridden = elements[start];
if (overridden != null) {
sum -= overridden.value;
}
elements[start++] = element;
if (start >= size) {
start = 0;
}
sum += element.value;
}
synchronized QueueTimeSample[] getElements() {
QueueTimeSample[] out = new QueueTimeSample[count];
if (count < size) {
System.arraycopy(elements, 0, out, 0, count);
} else {
System.arraycopy(elements, start, out, 0, size - start);
System.arraycopy(elements, 0, out, size - start, start);
}
return out;
}
}
}