[hibernate-issues] [Hibernate-JIRA] Created: (HHH-3628) Hilo optimizer problem in case of multiple threads accessing the sequence table

[Montagnon Cyril (JIRA)]

Hilo optimizer problem in case of multiple threads accessing the sequence table
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                 Key: HHH-3628
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3628
             Project: Hibernate Core
          Issue Type: Bug
    Affects Versions: 3.2.6
         Environment: Sybase
            Reporter: Montagnon Cyril


If 2 (or more) threads access the table storing the ids, this optimizer won't work and will try to insert entities with twice the same idea.

The problem is the way the HiLoOptimizer class generates the id : 

            public synchronized Serializable generate(AccessCallback callback) {
			if ( lastSourceValue < 0 ) {
				lastSourceValue = callback.getNextValue();
				while ( lastSourceValue <= 0 ) {
					lastSourceValue = callback.getNextValue();
				}
				hiValue = ( lastSourceValue * incrementSize ) + 1;
				value = hiValue - incrementSize;
			}
			else if ( value >= hiValue ) {
				lastSourceValue = callback.getNextValue();
				hiValue = ( lastSourceValue * incrementSize ) + 1;
			}
			return make( value++ );
		}

In the 'else if' part, the 'value' variable isn't reaffected, which means the current thread will try to insert entities with an id that has already been used by another thread. The value should be reset with hiValue - incrementSize.


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