| /** |
| * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. The ASF licenses this file to you 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 |
| * <p/> |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * <p/> |
| * 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 org.apache.storm.metric.internal; |
| |
| import java.io.Closeable; |
| import java.util.TimerTask; |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| /** |
| * This class is a utility to track the rate of something. |
| */ |
| public class RateTracker implements Closeable { |
| private final int bucketSizeMillis; |
| //Old Buckets and their length are only touched when rotating or gathering the metrics, which should not be that frequent |
| // As such all access to them should be protected by synchronizing with the RateTracker instance |
| private final long[] bucketTime; |
| private final long[] oldBuckets; |
| |
| private final AtomicLong bucketStart; |
| private final AtomicLong currentBucket; |
| |
| private final TimerTask task; |
| |
| /** |
| * Constructor. |
| * |
| * @param validTimeWindowInMils events that happened before validTimeWindowInMils are not considered when reporting the rate. |
| * @param numBuckets the number of time sildes to divide validTimeWindows. The more buckets, the smother the reported results |
| * will be. |
| */ |
| public RateTracker(int validTimeWindowInMils, int numBuckets) { |
| this(validTimeWindowInMils, numBuckets, -1); |
| } |
| |
| /** |
| * Constructor. |
| * |
| * @param validTimeWindowInMils events that happened before validTimeWindow are not considered when reporting the rate. |
| * @param numBuckets the number of time sildes to divide validTimeWindows. The more buckets, the smother the reported results |
| * will be. |
| * @param startTime if positive the simulated time to start the first bucket at. |
| */ |
| RateTracker(int validTimeWindowInMils, int numBuckets, long startTime) { |
| numBuckets = Math.max(numBuckets, 1); |
| bucketSizeMillis = validTimeWindowInMils / numBuckets; |
| if (bucketSizeMillis < 1) { |
| throw new IllegalArgumentException( |
| "validTimeWindowInMilis and numOfSildes cause each slide to have a window that is too small"); |
| } |
| bucketTime = new long[numBuckets - 1]; |
| oldBuckets = new long[numBuckets - 1]; |
| |
| bucketStart = new AtomicLong(startTime >= 0 ? startTime : System.currentTimeMillis()); |
| currentBucket = new AtomicLong(0); |
| if (startTime < 0) { |
| task = new Fresher(); |
| MetricStatTimer.timer.scheduleAtFixedRate(task, bucketSizeMillis, bucketSizeMillis); |
| } else { |
| task = null; |
| } |
| } |
| |
| /** |
| * Notify the tracker upon new arrivals. |
| * |
| * @param count number of arrivals |
| */ |
| public void notify(long count) { |
| currentBucket.addAndGet(count); |
| } |
| |
| /** |
| * Get report rate. |
| * @return the approximate average rate per second. |
| */ |
| public synchronized double reportRate() { |
| return reportRate(System.currentTimeMillis()); |
| } |
| |
| synchronized double reportRate(long currentTime) { |
| long duration = Math.max(1L, currentTime - bucketStart.get()); |
| long events = currentBucket.get(); |
| for (int i = 0; i < oldBuckets.length; i++) { |
| events += oldBuckets[i]; |
| duration += bucketTime[i]; |
| } |
| |
| return events * 1000.0 / duration; |
| } |
| |
| @Override |
| public void close() { |
| if (task != null) { |
| task.cancel(); |
| } |
| } |
| |
| /** |
| * Rotate the buckets a set number of times for testing purposes. |
| * |
| * @param numToEclipse the number of rotations to perform. |
| */ |
| final void forceRotate(int numToEclipse, long interval) { |
| long time = bucketStart.get(); |
| for (int i = 0; i < numToEclipse; i++) { |
| time += interval; |
| rotateBuckets(time); |
| } |
| } |
| |
| private synchronized void rotateBuckets(long time) { |
| long timeSpent = time - bucketStart.getAndSet(time); |
| long currentVal = currentBucket.getAndSet(0); |
| for (int i = 0; i < oldBuckets.length; i++) { |
| long tmpTime = bucketTime[i]; |
| bucketTime[i] = timeSpent; |
| timeSpent = tmpTime; |
| |
| long cnt = oldBuckets[i]; |
| oldBuckets[i] = currentVal; |
| currentVal = cnt; |
| } |
| } |
| |
| private class Fresher extends TimerTask { |
| @Override |
| public void run() { |
| rotateBuckets(System.currentTimeMillis()); |
| } |
| } |
| } |