Re: [aspectj-dev] IllegalMonitorStateException using locks

[Giles Reger <oneandonlygiles@xxxxxxxxx>]

An inelegant solution might be to intercept calls to wait on RWPriorityMonitorLock (which toy haven't locked) and replace them with calls of wait on the appropriate reentrant lock (which you have locked). Although this all seems a little convoluted and I'm not sure what the aim of the code is.

Giles

On May 1, 2013 8:44 PM, "Andrew Eisenberg" <andrew@xxxxxxxxxxxx> wrote:

Also, see my suggestion to your question on the forum: http://www.eclipse.org/forums/index.php/t/485975/

On Wed, May 1, 2013 at 12:40 PM, Giles Reger <oneandonlygiles@xxxxxxxxx> wrote:

When you call wait in lockRead and lockWrite you are not holding the monitor if the enclosing RWPriorityMonitorLock - you hold the monitor of a different lock.

On May 1, 2013 6:06 PM, "Pedro Martins" <pmp.martins@xxxxxxxxxxxxxxxxx> wrote:

Hellow, I have a code that uses multiple threads, and so I need read and write locks for it. Simply put, this is what I have so far:

[code]
public interface IReadWriteLock{
    public void lockWrite();
    public void unlockWrite();
   
    public void lockRead();
    public void unlockRead();
}
[/code]

This interface would then be implemented by a class:

[code]
public class RWPriorityMonitorLock implements IReadWriteLock{
   
    private boolean dbWritting, writterWantsIn;
    private int numReaders;
   
    public RWPriorityMonitorLock() {
        dbWritting = false;
        numReaders = 0;
        writterWantsIn = false;
    }
   
    @Override
    public void lockRead() {
        while(dbWritting || writterWantsIn)
            try{
                wait();
            }catch(InterruptedException e){ e.printStackTrace(); }
           
        numReaders++;
    }

    @Override
    public void unlockRead() {
        numReaders--;
       
        if(numReaders == 0)
            notify();
    }

    @Override
    public void lockWrite() {
        writterWantsIn = true;
        while(numReaders > 0 || dbWritting)
            try{
                wait();
            }catch(InterruptedException e){ e.printStackTrace(); }
       
        dbWritting = true;
        writterWantsIn = false;
    }

    @Override
    public void unlockWrite() {
        dbWritting = false;
        notifyAll();
    }
}
[/code]

Now, in order to force synchronization , I use the aspect:

[code]
public aspect IReadWriteLockAspect {

    private static Map<IReadWriteLock, Lock> allLocks = new HashMap<>();

    pointcut lockReflectInit(): call(public Object
            java.lang.reflect.Constructor.newInstance(..)); 

    pointcut hardWaitMutex():
        call(public void IReadWriteLock+.*());

    void around(): hardWaitMutex(){
        IReadWriteLock currentLock = (IReadWriteLock) thisJoinPoint.getTarget();
        Lock mutex = allLocks.get(currentLock);
        mutex.lock();
        try{
            proceed();
        }finally{
            mutex.unlock();
        }
    }

    Object around(): lockReflectInit() {
        IReadWriteLock lockType = (IReadWriteLock)proceed();
        allLocks.put(lockType, new ReentrantLock(true));
        return lockType;
    }
}
[/code]

The point is, every time I try to execute something, I get an IllegalMonitorStateException. In this link:
http://stackoverflow.com/questions/1537116/illegalmonitorstateexception-on-wait-call

They say that the thread must own the monitor, but I don't see where that is not happening. Can some one help?

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