com.venky.cache.UnboundedCache Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of common Show documentation

Commonly used programming tasks in java

The newest version!

package com.venky.cache;

import java.util.HashMap;
import java.util.concurrent.ConcurrentHashMap;

public abstract class UnboundedCache extends ConcurrentHashMap {

	/**
	 * 
	 */
	private static final long serialVersionUID = -279156550678934353L;
	@SuppressWarnings("unchecked")
	public V get(Object key){
		K k = (K)key;
		V v = super.get(k);
		if (v == null){
			v = getValue(k); //Wastful getValue is better than blocking GetValue.
			if (v != null){
				synchronized (this){
					V vExisting = super.get(k);
					if (vExisting == null){
						super.put(k, v);
					}else {
						v = vExisting;
					}
				}
			}
		}
		return v;
	}
	
	protected abstract V getValue(K key);
}