| /** |
| * 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 com.alibaba.jstorm.utils; |
| |
| import java.util.Iterator; |
| import java.util.LinkedList; |
| import java.util.concurrent.LinkedBlockingDeque; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Expires keys that have not been updated in the configured number of seconds. The algorithm used will take between expirationSecs and expirationSecs * (1 + 1 |
| * / (numBuckets-1)) to actually expire the message. |
| * |
| * get, put, remove, containsKey, and size take O(numBuckets) time to run. |
| * |
| * The advantage of this design is that the expiration thread only locks the object for O(1) time, meaning the object is essentially always available for |
| * poll/offer |
| */ |
| public class TimeCacheQueue<K> { |
| // this default ensures things expire at most 50% past the expiration time |
| public static final int DEFAULT_NUM_BUCKETS = 3; |
| |
| public static interface ExpiredCallback<K> { |
| public void expire(K entry); |
| } |
| |
| public static class DefaultExpiredCallback<K> implements ExpiredCallback<K> { |
| protected static final Logger LOG = LoggerFactory.getLogger(DefaultExpiredCallback.class); |
| |
| protected String queueName; |
| |
| public DefaultExpiredCallback(String queueName) { |
| this.queueName = queueName; |
| } |
| |
| public void expire(K entry) { |
| LOG.info("TimeCacheQueue " + queueName + " entry:" + entry + ", timeout"); |
| } |
| } |
| |
| protected LinkedList<LinkedBlockingDeque<K>> _buckets; |
| |
| protected final Object _lock = new Object(); |
| protected Thread _cleaner; |
| protected ExpiredCallback _callback; |
| |
| public TimeCacheQueue(int expirationSecs, int numBuckets, ExpiredCallback<K> callback) { |
| if (numBuckets < 2) { |
| throw new IllegalArgumentException("numBuckets must be >= 2"); |
| } |
| _buckets = new LinkedList<LinkedBlockingDeque<K>>(); |
| for (int i = 0; i < numBuckets; i++) { |
| _buckets.add(new LinkedBlockingDeque<K>()); |
| } |
| |
| _callback = callback; |
| final long expirationMillis = expirationSecs * 1000L; |
| final long sleepTime = expirationMillis / (numBuckets - 1); |
| _cleaner = new Thread(new Runnable() { |
| public void run() { |
| try { |
| while (true) { |
| LinkedBlockingDeque<K> dead = null; |
| |
| Thread.sleep(sleepTime); |
| |
| synchronized (_lock) { |
| dead = _buckets.removeLast(); |
| _buckets.addFirst(new LinkedBlockingDeque<K>()); |
| } |
| if (_callback != null) { |
| for (K entry : dead) { |
| _callback.expire(entry); |
| } |
| } |
| } |
| } catch (InterruptedException ex) { |
| |
| } |
| } |
| }); |
| _cleaner.setDaemon(true); |
| _cleaner.start(); |
| } |
| |
| public TimeCacheQueue(int expirationSecs, ExpiredCallback<K> callback) { |
| this(expirationSecs, DEFAULT_NUM_BUCKETS, callback); |
| } |
| |
| public TimeCacheQueue(int expirationSecs) { |
| this(expirationSecs, DEFAULT_NUM_BUCKETS, null); |
| } |
| |
| public TimeCacheQueue(int expirationSecs, int numBuckets) { |
| this(expirationSecs, numBuckets, null); |
| } |
| |
| public boolean containsKey(K entry) { |
| synchronized (_lock) { |
| for (LinkedBlockingDeque<K> bucket : _buckets) { |
| if (bucket.contains(entry)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| } |
| |
| public K poll() { |
| synchronized (_lock) { |
| Iterator<LinkedBlockingDeque<K>> itor = _buckets.descendingIterator(); |
| while (itor.hasNext()) { |
| LinkedBlockingDeque<K> bucket = itor.next(); |
| K entry = bucket.poll(); |
| if (entry != null) { |
| return entry; |
| } |
| } |
| |
| return null; |
| } |
| } |
| |
| public void offer(K entry) { |
| synchronized (_lock) { |
| LinkedBlockingDeque<K> bucket = _buckets.getFirst(); |
| |
| bucket.offer(entry); |
| } |
| } |
| |
| public void remove(K entry) { |
| synchronized (_lock) { |
| for (LinkedBlockingDeque<K> bucket : _buckets) { |
| if (bucket.contains(entry)) { |
| bucket.remove(entry); |
| return; |
| } |
| } |
| return; |
| } |
| } |
| |
| public int size() { |
| synchronized (_lock) { |
| int size = 0; |
| for (LinkedBlockingDeque<K> bucket : _buckets) { |
| size += bucket.size(); |
| } |
| return size; |
| } |
| } |
| |
| @Override |
| protected void finalize() throws Throwable { |
| try { |
| _cleaner.interrupt(); |
| } finally { |
| super.finalize(); |
| } |
| } |
| |
| } |