Problem in using the Unreferenced interface

Question

I let my RemoteObject to implement the Unreferenced interface to handle with the unexpectly abort client. but I have a question about how to use such interface in my remote object.
My first thought about it is simple :
class RemoteObject extends UnicastRemoteObject implements Unreferenced {
    public long lock(final int recno) {
        this.lockedRecNo = recno;
        this.lockCookie = LockManager.getInstance().lock(recno);
        return lockcookie;
    public void unreferenced() {
        this.unlock(this.lockedRecNo, this.lockCookie);
}I think it is absolutely wrong under such scenario, since the unreference does not take effect immediately and we surely have only one RemoteObject, during this time. someother client may lock on other records, When performing the unreferenced, we may work on the incorrect record number and cookie.
Then I improved it as
class RemoteObject extends UnicastRemoteObject implements Unreferenced {
    private HashMap lockedRecord = new HashMap();
    public long lock(final int recno) {
        this.lockedRecNo = recno;
        this.lockCookie = LockManager.getInstance().lock(recno);
        lockedRecord.put(new Integer(recno), new Long(lockCookie))
        return lockcookie;
    public void unlock(final int recno, final int cookie) {
        LockManager.getInstance().unlock(recno, cookie);
        lockedRecord.remove(new Integer(recno));
    public void unreferenced() {
        //get all that haven't released lock from the HashMap
        //do a loop
        **loop** {
        this.unlock(this.lockedRecNo, this.lockCookie);
    }There are still some problems. maybe when we are executing the unreference, there is a client who are holding a lock and doing the update action, then we may wrongly release his lock.
I can not figure out a good enough way to handle this. can any one help me on this. thx in advance.

Answer 1

Hi.. Actually, it is not part of the[b] real world problem, I just want to provide a way to clean up the staleness record. If considering this. do you guys thing the approach 2 of the first posting is a way(maybe not a good way), except I should change the hashmap to hashtable to avoid the concurrent accessing... appreciate for any reply from u.