Java code example: simple singleton lock using with Atomic variables

I needed a very simple lock system for a software demo for operation on HashMap, instead of using ReentrantLock from java.util.concurrent.locks i chose to use Atomic classes from java.util.concurrent.atomic.* .

My demo has a very LONG blocking thread that writes on a shared HashMap, the following class permits me to tune the sleep time for the lock without using a syncronized queue.

Using AtomicInteger in place of AtomicBoolean gives the possibility to use multi-level lock levels

package com.simonecaruso;
 
import java.util.concurrent.atomic.AtomicInteger;
 
public class ConfigLock {
 
	static ConfigLock uniq  = null;
	static AtomicInteger i = 0;
 
	public static synchronized ConfigLock getInstance(){
		if(uniq == null)
			uniq = new ConfigLock();
		return uniq;
	}
 
	public static boolean isLocked(){
		return i.intValue() &gt; 0 ? true : false;
	}
 
	public static boolean tryLock(){
		return i.compareAndSet(0, 1);
	}
 
	public static boolean unLock(){
		return i.compareAndSet(1, 0);
	}
 
	public static boolean lock() throws InterruptedException{
		while(i.compareAndSet(0, 1) != true)
			Thread.sleep(100);
		return true;
	}
}

One Reply to “Java code example: simple singleton lock using with Atomic variables”

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March 10, 2015 at 17:28

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