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package net.anotheria.util.concurrency;


import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * UnsafeIdBasedLockManager class.
 *
 * @author another
 * @version $Id: $Id
 */
public class UnsafeIdBasedLockManager extends AbstractIdBasedLockManager
        implements IdBasedLockManager {
    /**
     * Serialization version unique identifier.
     */
    private static final long serialVersionUID = -4257919838109398407L;
    private ConcurrentMap> locks = new ConcurrentHashMap<>();

    /** {@inheritDoc} */
    @Override
    public IdBasedLock obtainLock(K id) {
        IdBasedLock lock = new IdBasedLock<>(id, this);
        IdBasedLock myLock = locks.putIfAbsent(id, lock);
        if (myLock == null)
            return lock;
        myLock.lock();
        myLock.increaseRefCount();
        if (myLock.getRefCount().get() == 1) {
            //someone else have probably removed the lock in the mean time, re-add
            IdBasedLock raceCond = locks.put(id, myLock);
            //if race cond!= null we have a synch problem here, but we are unsafe after all!
            //future use - merge both locks
        }

        myLock.unlockWithoutRelease();
        return myLock;
    }

    /** {@inheritDoc} */
    @Override
    public void releaseLock(IdBasedLock lock) {
        K id = lock.getId();
        lock.lock();
        if (lock.getRefCount().get() == 1) {
            IdBasedLock previous = locks.remove(id);
        }
        lock.decreaseRefCount();
        lock.unlockWithoutRelease();
    }

    /** {@inheritDoc} */
    @Override
    protected Map> getLockMap() {
        return locks;
    }
}