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snpesnpe
 Post subject: LockMode problem
PostPosted: Tue Nov 23, 2004 1:55 pm 
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Joined: Sat Jun 12, 2004 4:49 pm
Posts: 915
Hello,
I try next scenario with hibernate :

Step 1) user populate rows in session A and close session A

Step 2) use choose row 1 and change

Step 3) user call save and commit work

It work fine except that another user can update row 1 between step 1 and step 2 and his changes aren't saved

Now I want lock row in step 2 and do :

step 1) populate in session A and close session A

step 2) user choose row 1 and when he update row I open new session B and new transaction T and call lock(row,LockMode.UPGRADE_NOWAIT)

another user can't update row 1 now

step 3) User choose save and I call
B.update(row);
T.commit();
B.close();

However, Hibernate doesn't update row.Why ?

I try this scenario in Oracle sqlplus with :

select *
from mytab
where id=1
for update of id,name;

<...
<1 row selected

-- another user can't change row 1

update mytab set name='another name' where id=1;

< 1 row updated

commit;

< commit complete.

regards
Haris Peco
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christian
 Post subject:
PostPosted: Tue Nov 23, 2004 1:57 pm 
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I've no idea what you are talking about.

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snpesnpe
 Post subject:
PostPosted: Tue Nov 23, 2004 2:24 pm 
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Posts: 915
Christian,
It is simple.
I can't update row after LockMode.UPGRADE in same session, same transaction

select .. FOR UPDATE OF denied update form another transaction, but not from same transaction

regards
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anthony
 Post subject:
PostPosted: Tue Nov 23, 2004 2:27 pm 
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Posts: 1977
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Quote:
I can't update row after LockMode.UPGRADE in same session, same transaction


you mean after locking with lockmode upgrade or upgrade no wait, changes made to you persistent object can't be persisted?

are you sure about the transaction begin? when is it called?

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snpesnpe
 Post subject:
PostPosted: Tue Nov 23, 2004 2:42 pm 
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Posts: 915
This is code :
LockMode.UPGRADE

lock on change :

try {
openTransaction();
transactionSession.lock(getCurrentBean(),
LockMode.UPGRADE_NOWAIT);
getCurrentBean().setChanged(changed);
} catch (HibernateException e) {
rollback();
fireMessageListener("setchanged.exception");
if (logger.isDebugEnabled())
logger.debug(e.getMessage());
}

private void openTransaction () throws HibernateException {
if (transactionSession == null) {
transactionSession = getSessionFactory().openSession();
transaction = transactionSession.beginTransaction();
}
}

update :

try {
openTransaction();
transactionSession.update(getCurrentBean());
commitTransaction();
} catch (HibernateException e) {
rollback();
fireMessageListener("save.update");
if (logger.isDebugEnabled()) {
logger.debug(e.getMessage());
}
} finally {
refresh();
}

private void commitTransaction() throws HibernateException {
if (transaction != null) {
//transactionSession.flush();
transaction.commit();
transactionSession.close();
}
transactionSession = null;
transaction=null;
}
rollback :

try {
rollbackTransaction();
} catch (HibernateException e) {
fireMessageListener("rollback.exception");
logger.error(e.getMessage());
}
refresh();

private void rollbackTransaction() throws HibernateException {
if (transaction != null) {
transaction.rollback();
transactionSession.close();
}
transactionSession = null;
transaction = null;
}

refresh load rows in another session (without transaction - it is Oracle)

openTransaction,commitTransaction and roolbackTransaction will open only one transaction

regards
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christian
 Post subject:
PostPosted: Tue Nov 23, 2004 2:44 pm 
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Posts: 4592
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Please repost, use proper indentation and code blocks.

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anthony
 Post subject:
PostPosted: Tue Nov 23, 2004 2:47 pm 
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Joined: Thu Dec 18, 2003 9:55 am
Posts: 1977
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transactionSession.update(getCurrentBean());


is your instance detached? sounds strange this may be broken, lock also re attach an instance if it is detached so you don't need to call update...

also prefer threadlocal holding for transaction

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snpesnpe
 Post subject:
PostPosted: Tue Nov 23, 2004 2:52 pm 
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Joined: Sat Jun 12, 2004 4:49 pm
Posts: 915
lock
Code:
         try {
                openTransaction();
               
                transactionSession.lock(getCurrentBean(),
                        LockMode.UPGRADE_NOWAIT);
                getCurrentBean().setChanged(changed);
            } catch (HibernateException e) {
                rollback();
                fireMessageListener("setchanged.exception");
                if (logger.isDebugEnabled())
                    logger.debug(e.getMessage());
            }


commit

Code:
         try {
            openTransaction();
            transactionSession.update(getCurrentBean());
            commitTransaction();
        } catch (HibernateException e) {
            rollback();
            fireMessageListener("save.update");
            if (logger.isDebugEnabled()) {
                logger.debug(e.getMessage());
            }
        } finally {
            refresh();
        }


rollback :

Code:
        try {
            rollbackTransaction();
        } catch (HibernateException e) {
            fireMessageListener("rollback.exception");
            logger.error(e.getMessage());
        } finally {
           refresh();
        }


methods :
Code:
private void openTransaction () throws HibernateException {
        if (transactionSession == null) {
            transactionSession = getSessionFactory().openSession();
            transaction = transactionSession.beginTransaction();
        }
    }
   
    private void commitTransaction() throws HibernateException {
        if (transaction != null) {
            //transactionSession.flush();
            transaction.commit();
            transactionSession.close();
        }
        transactionSession = null;
        transaction=null;
    }
    private void rollbackTransaction() throws HibernateException {
        if (transaction != null) {
            transaction.rollback();
            transactionSession.close();
        }
        transactionSession = null;
        transaction = null;
    }


regards
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christian
 Post subject:
PostPosted: Tue Nov 23, 2004 2:54 pm 
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Posts: 4592
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I've still no idea what this is about, so I'm giving up.

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snpesnpe
 Post subject:
PostPosted: Tue Nov 23, 2004 3:30 pm 
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Joined: Sat Jun 12, 2004 4:49 pm
Posts: 915
Anthony, Christian,

I make test case (one test success and 2 test fail - test name talk
Code:
package org.springframework.richclient.test.hibernate;

import org.springframework.richclient.model.hibernate.AdmSnpeMenus;

import net.sf.hibernate.HibernateException;
import net.sf.hibernate.LockMode;
import net.sf.hibernate.Session;
import net.sf.hibernate.Transaction;

/**
* @author snpe
*
*/
public class HibernateUpgradeTests extends BaseHibernateWithouSpringTests {

    private Session session;
    private Session transactionSession;
    private Transaction transaction;
   
    protected void setUp() throws Exception {
        AdmSnpeMenus menu = getMenu();
        menu.setImg("neki.gif");
        openTransaction();
        transactionSession.update(menu);
        commitTransaction();
    }
   
    protected void tearDown() throws Exception {
    }
   
    public HibernateUpgradeTests(String name) {
        super(name);
    }

    public void testLockUpgradeSuccess() throws HibernateException {
        AdmSnpeMenus menu = getMenu();
        assertTrue("id=neki",menu.getId().equals("neki"));
        assertTrue("img = neki.gif",menu.getImg().equals("neki.gif"));
        openTransaction();
        transactionSession.lock(menu,LockMode.UPGRADE_NOWAIT);
        menu.setImg("another.gif");
        transactionSession.update(menu);
        commitTransaction();
        menu = getMenu();
        assertTrue("neki=another.gif",menu.getImg().equals("another.gif"));
    }
   
    public void testLockUpgradeFail1() throws HibernateException {
        AdmSnpeMenus menu = getMenu();
        assertTrue("id=neki",menu.getId().equals("neki"));
        assertTrue("img = neki.gif",menu.getImg().equals("neki.gif"));
        menu.setImg("another.gif");
        openTransaction();
        transactionSession.lock(menu,LockMode.UPGRADE_NOWAIT);
        transactionSession.update(menu);
        commitTransaction();
        menu = getMenu();
        assertTrue("neki=another.gif",menu.getImg().equals("another.gif"));
    }
   
    public void testLockUpgradeFail2() throws HibernateException {
        AdmSnpeMenus menu = getMenu();
        assertTrue("id=neki",menu.getId().equals("neki"));
        assertTrue("img = neki.gif",menu.getImg().equals("neki.gif"));
        openTransaction();
        menu.setImg("another.gif");
        transactionSession.lock(menu,LockMode.UPGRADE_NOWAIT);
        transactionSession.update(menu);
        commitTransaction();
        menu = getMenu();
        assertTrue("neki=another.gif",menu.getImg().equals("another.gif"));
    }
   
    private AdmSnpeMenus getMenu() throws HibernateException {
        session = getSessionFactory().openSession();
        String query = "from " + AdmSnpeMenus.class.getName()
        + " as menu where menu.id = 'neki' ";
        AdmSnpeMenus menu = (AdmSnpeMenus) session.find(query).get(0);
        session.close();
        return menu;
    }
   
    private void openTransaction () throws HibernateException {
        if (transactionSession == null) {
            transactionSession = getSessionFactory().openSession();
            transaction = transactionSession.beginTransaction();
        }
    }
   
    private void commitTransaction() throws HibernateException {
        if (transaction != null) {
            //transactionSession.flush();
            transaction.commit();
            transactionSession.close();
        }
        transactionSession = null;
        transaction=null;
    }
    private void rollbackTransaction() throws HibernateException {
        if (transaction != null) {
            transaction.rollback();
            transactionSession.close();
        }
        transactionSession = null;
        transaction = null;
    }

}



regards
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anthony
 Post subject:
PostPosted: Tue Nov 23, 2004 3:35 pm 
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Joined: Thu Dec 18, 2003 9:55 am
Posts: 1977
Location: France
this is the expected behaviour

Code:
    public void testLockUpgradeSuccess() throws HibernateException {
        AdmSnpeMenus menu = getMenu();
        assertTrue("id=neki",menu.getId().equals("neki"));
        assertTrue("img = neki.gif",menu.getImg().equals("neki.gif"));
        openTransaction();
        transactionSession.lock(menu,LockMode.UPGRADE_NOWAIT);
        menu.setImg("another.gif");
// update isn't necessary here       
//transactionSession.update(menu);
        commitTransaction();
        menu = getMenu();
        assertTrue("neki=another.gif",menu.getImg().equals("another.gif"));
    }
   
    public void testLockUpgradeFail1() throws HibernateException {
        AdmSnpeMenus menu = getMenu();
        assertTrue("id=neki",menu.getId().equals("neki"));
        assertTrue("img = neki.gif",menu.getImg().equals("neki.gif"));
        menu.setImg("another.gif");
        openTransaction();
// here you're saying to re attach with lock and detached instance you it //hasn't been modified during detachement       
transactionSession.lock(menu,LockMode.UPGRADE_NOWAIT);

// here you're telling to reattach a detached modified instance, this one isn't detached anymore because of the previous session.lock....
        transactionSession.update(menu);
        commitTransaction();
        menu = getMenu();
        assertTrue("neki=another.gif",menu.getImg().equals("another.gif"));
    }


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Last edited by anthony on Tue Nov 23, 2004 3:39 pm, edited 1 time in total.

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snpesnpe
 Post subject:
PostPosted: Tue Nov 23, 2004 3:38 pm 
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Posts: 915
Why ? Why lock have Object parameter ?

regards
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anthony
 Post subject:
PostPosted: Tue Nov 23, 2004 3:40 pm 
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Joined: Thu Dec 18, 2003 9:55 am
Posts: 1977
Location: France
i've edited my previous reply, read it

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snpesnpe
 Post subject:
PostPosted: Tue Nov 23, 2004 3:48 pm 
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Joined: Sat Jun 12, 2004 4:49 pm
Posts: 915
Anthony,
I make swing application (spring rcp) and this is scenario :

- user populate rows and he haven't any lock
- when user type any character in form I want lock this row with user's changes
- when user call sav button I commit transaction

What is correct use case ?

Thanks
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anthony
 Post subject:
PostPosted: Tue Nov 23, 2004 4:36 pm 
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Joined: Thu Dec 18, 2003 9:55 am
Posts: 1977
Location: France
why don't you use versionning?

pessimistic lock is really heavy and in your case, you should have a very long transaction

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