com.netflix.eureka.util.MeasuredRate Maven / Gradle / Ivy

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/*
 * Copyright 2012 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.eureka.util;

import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.atomic.AtomicLong;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Utility class for getting a count in last X milliseconds.
 *
 * @author Karthik Ranganathan,Greg Kim
 */
public class MeasuredRate {
    private static final Logger logger = LoggerFactory
            .getLogger(MeasuredRate.class);
    private final AtomicLong lastBucket = new AtomicLong(0);
    private final AtomicLong currentBucket = new AtomicLong(0);
    private final long sampleInterval;
    private Timer timer = new Timer("Eureka-MeasureRateTimer", true);

    /**
     * @param sampleInterval
     *            in milliseconds
     */
    public MeasuredRate(long sampleInterval) {
        this.sampleInterval = sampleInterval;
        timer.schedule(new TimerTask() {

            @Override
            public void run() {
                try {
                    // Zero out the current bucket.
                    lastBucket.set(currentBucket.getAndSet(0));
                } catch (Throwable e) {
                    logger.error("Cannot reset the Measured Rate", e);
                }
            }
        }, sampleInterval, sampleInterval);
    }

    /**
     * Returns the count in the last sample interval.
     */
    public long getCount() {
        return lastBucket.get();
    }

    /**
     * Increments the count in the current sample interval.
     */
    public void increment() {
        currentBucket.incrementAndGet();
    }
}