参考storm中的RotatingMap实现key超时处理

storm0.8.1以后的RotatingMap完全可以独立于storm用来实现hashmap的key超时删除，并调用回调函数

RotatingMap.java：

 

import java.util.HashMap;import java.util.Iterator;import java.util.LinkedList;import java.util.Map;import java.util.Map.Entry;/** * 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 gets/puts. */public class RotatingMap<K, V> {    //this default ensures things expire at most 50% past the expiration time    private static final int DEFAULT_NUM_BUCKETS = 3;    public static interface ExpiredCallback<K, V> {        public void expire(K key, V val);    }    private LinkedList<HashMap<K, V>> _buckets;    private ExpiredCallback _callback;        public RotatingMap(int numBuckets, ExpiredCallback<K, V> callback) {        if(numBuckets<2) {            throw new IllegalArgumentException("numBuckets must be >= 2");        }        _buckets = new LinkedList<HashMap<K, V>>();        for(int i=0; i<numBuckets; i++) {            _buckets.add(new HashMap<K, V>());        }        _callback = callback;    }    public RotatingMap(ExpiredCallback<K, V> callback) {        this(DEFAULT_NUM_BUCKETS, callback);    }    public RotatingMap(int numBuckets) {        this(numBuckets, null);    }           public Map<K, V> rotate() {        Map<K, V> dead = _buckets.removeLast();        _buckets.addFirst(new HashMap<K, V>());        if(_callback!=null) {            for(Entry<K, V> entry: dead.entrySet()) {                _callback.expire(entry.getKey(), entry.getValue());            }        }        return dead;    }    public boolean containsKey(K key) {        for(HashMap<K, V> bucket: _buckets) {            if(bucket.containsKey(key)) {                return true;            }        }        return false;    }    public V get(K key) {        for(HashMap<K, V> bucket: _buckets) {            if(bucket.containsKey(key)) {                return bucket.get(key);            }        }        return null;    }    public void put(K key, V value) {        Iterator<HashMap<K, V>> it = _buckets.iterator();        HashMap<K, V> bucket = it.next();        bucket.put(key, value);        while(it.hasNext()) {            bucket = it.next();            bucket.remove(key);        }    }            public Object remove(K key) {        for(HashMap<K, V> bucket: _buckets) {            if(bucket.containsKey(key)) {                return bucket.remove(key);            }        }        return null;    }    public int size() {        int size = 0;        for(HashMap<K, V> bucket: _buckets) {            size+=bucket.size();        }        return size;    }    }

EventHandler.java

public class EventHandler<k, v> implements RotatingMap.ExpiredCallback<k, v>{ @Override public void expire(Object key, Object val) {  System.out.println("key=" + key + ",val=" + val); }}

 

RotatingMapStarter.java：

import java.sql.Date;import java.text.SimpleDateFormat;public class RotatingMapStarter{ RotatingMap<String, String> m_rotatingMap = null; RotatingMap.ExpiredCallback<String, String> m_eventHandler = null; long m_lastRotate = System.currentTimeMillis(); long m_rotateTime; @SuppressWarnings( { "unchecked", "rawtypes" }) public RotatingMapStarter(int n, int rotateTime) // rotateTime :rotate for              // second {  m_eventHandler = new EventHandler<String, String>();  m_rotatingMap = new RotatingMap<String, String>(4, m_eventHandler);  m_lastRotate = System.currentTimeMillis();  m_rotateTime = 1000L * rotateTime; // millisecond } public RotatingMap<String, String> getM_rotatingMap() {  return m_rotatingMap; } public void setM_rotatingMap(RotatingMap<String, String> m_rotatingMap) {  this.m_rotatingMap = m_rotatingMap; } public void StartConnMonitor() {  Thread thread = new Thread("Server Monitor")  {   @SuppressWarnings("static-access")   public void run()   {    while (true)    {     try     {      Thread.currentThread().sleep(1000);     }     catch (InterruptedException e)     {      e.printStackTrace();     }          long now = System.currentTimeMillis();     if (now - m_lastRotate > m_rotateTime)     {      m_rotatingMap.rotate();      m_lastRotate = now;                 }     else     {      //System.out.println(now - m_lastRotate);      SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式      System.out.println(df.format(new Date(now)));// new Date()为获取当前系统时间     }    }   }  };  thread.start(); } /**  * @param args  */ public static void main(String[] args) {  RotatingMapStarter rotatingMapStarter = new RotatingMapStarter(4, 10);  String value = "001";  String key = "value";  rotatingMapStarter.getM_rotatingMap().put(key, value);  rotatingMapStarter.StartConnMonitor(); }}