| package backtype.storm.utils; |
| |
| 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. |
| */ |
| //deprecated in favor of non-threaded RotatingMap |
| @Deprecated |
| public class TimeCacheMap<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 final Object _lock = new Object(); |
| private Thread _cleaner; |
| private ExpiredCallback _callback; |
| |
| public TimeCacheMap(int expirationSecs, 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; |
| final long expirationMillis = expirationSecs * 1000L; |
| final long sleepTime = expirationMillis / (numBuckets-1); |
| _cleaner = new Thread(new Runnable() { |
| public void run() { |
| try { |
| while(true) { |
| Map<K, V> dead = null; |
| Time.sleep(sleepTime); |
| synchronized(_lock) { |
| 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()); |
| } |
| } |
| } |
| } catch (InterruptedException ex) { |
| |
| } |
| } |
| }); |
| _cleaner.setDaemon(true); |
| _cleaner.start(); |
| } |
| |
| public TimeCacheMap(int expirationSecs, ExpiredCallback<K, V> callback) { |
| this(expirationSecs, DEFAULT_NUM_BUCKETS, callback); |
| } |
| |
| public TimeCacheMap(int expirationSecs) { |
| this(expirationSecs, DEFAULT_NUM_BUCKETS); |
| } |
| |
| public TimeCacheMap(int expirationSecs, int numBuckets) { |
| this(expirationSecs, numBuckets, null); |
| } |
| |
| |
| public boolean containsKey(K key) { |
| synchronized(_lock) { |
| for(HashMap<K, V> bucket: _buckets) { |
| if(bucket.containsKey(key)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| } |
| |
| public V get(K key) { |
| synchronized(_lock) { |
| for(HashMap<K, V> bucket: _buckets) { |
| if(bucket.containsKey(key)) { |
| return bucket.get(key); |
| } |
| } |
| return null; |
| } |
| } |
| |
| public void put(K key, V value) { |
| synchronized(_lock) { |
| 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) { |
| synchronized(_lock) { |
| for(HashMap<K, V> bucket: _buckets) { |
| if(bucket.containsKey(key)) { |
| return bucket.remove(key); |
| } |
| } |
| return null; |
| } |
| } |
| |
| public int size() { |
| synchronized(_lock) { |
| int size = 0; |
| for(HashMap<K, V> bucket: _buckets) { |
| size+=bucket.size(); |
| } |
| return size; |
| } |
| } |
| |
| public void cleanup() { |
| _cleaner.interrupt(); |
| } |
| } |