| /** |
| * 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 |
| * |
| * 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 storm.starter.tools; |
| |
| import backtype.storm.utils.Time; |
| import org.apache.commons.collections.buffer.CircularFifoBuffer; |
| |
| /** |
| * This class tracks the time-since-last-modify of a "thing" in a rolling fashion. |
| * <p></p> |
| * For example, create a 5-slot tracker to track the five most recent time-since-last-modify. |
| * <p></p> |
| * You must manually "mark" that the "something" that you want to track -- in terms of modification times -- has just |
| * been modified. |
| */ |
| public class NthLastModifiedTimeTracker { |
| |
| private static final int MILLIS_IN_SEC = 1000; |
| |
| private final CircularFifoBuffer lastModifiedTimesMillis; |
| |
| public NthLastModifiedTimeTracker(int numTimesToTrack) { |
| if (numTimesToTrack < 1) { |
| throw new IllegalArgumentException( |
| "numTimesToTrack must be greater than zero (you requested " + numTimesToTrack + ")"); |
| } |
| lastModifiedTimesMillis = new CircularFifoBuffer(numTimesToTrack); |
| initLastModifiedTimesMillis(); |
| } |
| |
| private void initLastModifiedTimesMillis() { |
| long nowCached = now(); |
| for (int i = 0; i < lastModifiedTimesMillis.maxSize(); i++) { |
| lastModifiedTimesMillis.add(Long.valueOf(nowCached)); |
| } |
| } |
| |
| private long now() { |
| return Time.currentTimeMillis(); |
| } |
| |
| public int secondsSinceOldestModification() { |
| long modifiedTimeMillis = ((Long) lastModifiedTimesMillis.get()).longValue(); |
| return (int) ((now() - modifiedTimeMillis) / MILLIS_IN_SEC); |
| } |
| |
| public void markAsModified() { |
| updateLastModifiedTime(); |
| } |
| |
| private void updateLastModifiedTime() { |
| lastModifiedTimesMillis.add(now()); |
| } |
| |
| } |