| /** |
| * 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 backtype.storm.metric.internal; |
| |
| import java.util.Timer; |
| import java.util.TimerTask; |
| import java.util.concurrent.atomic.AtomicLong; |
| |
| /** |
| * This class is a utility to track the rate of something. |
| */ |
| public class RateTracker{ |
| 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; |
| |
| /** |
| * @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); |
| } |
| |
| /** |
| * @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; |
| } |
| |
| 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 { |
| public void run () { |
| rotateBuckets(System.currentTimeMillis()); |
| } |
| } |
| |
| public static void main (String args[]) throws Exception { |
| final int number = (args.length >= 1) ? Integer.parseInt(args[0]) : 100000000; |
| for (int i = 0; i < 10; i++) { |
| testRate(number); |
| } |
| } |
| |
| private static void testRate(int number) { |
| RateTracker rt = new RateTracker(10000, 10); |
| long start = System.currentTimeMillis(); |
| for (int i = 0; i < number; i++) { |
| rt.notify(1); |
| if ((i % 1000000) == 0) { |
| //There is an issue with some JVM versions where an integer for loop that takes a long time |
| // can starve other threads resulting in the timer thread not getting called. |
| // This is a work around for that, and we still get the same results. |
| Thread.yield(); |
| } |
| } |
| long end = System.currentTimeMillis(); |
| double rate = rt.reportRate(); |
| rt.close(); |
| System.out.printf("time %,8d count %,8d rate %,15.2f reported rate %,15.2f\n", end-start,number, ((number * 1000.0)/(end-start)), rate); |
| } |
| } |