org.hibernate.id.enhanced.Optimizer Maven / Gradle / Ivy
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2008-2011, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.id.enhanced;
import java.io.Serializable;
import org.hibernate.id.IntegralDataTypeHolder;
/**
* Performs optimization on an optimizable identifier generator. Typically
* this optimization takes the form of trying to ensure we do not have to
* hit the database on each and every request to get an identifier value.
*
* Optimizers work on constructor injection. They should provide
* a constructor with the following arguments
* - java.lang.Class - The return type for the generated values
* - int - The increment size
*
*
* @author Steve Ebersole
*/
public interface Optimizer {
/**
* Generate an identifier value accounting for this specific optimization.
*
* All known implementors are synchronized. Consider carefully if a new
* implementation could drop this requirement.
*
* @param callback Callback to access the underlying value source.
* @return The generated identifier value.
*/
public Serializable generate(AccessCallback callback);
/**
* A common means to access the last value obtained from the underlying
* source. This is intended for testing purposes, since accessing the
* underlying database source directly is much more difficult.
*
* @return The last value we obtained from the underlying source;
* null indicates we have not yet consulted with the source.
*/
public IntegralDataTypeHolder getLastSourceValue();
/**
* Retrieves the defined increment size.
*
* @return The increment size.
*/
public int getIncrementSize();
/**
* Are increments to be applied to the values stored in the underlying
* value source?
*
* @return True if the values in the source are to be incremented
* according to the defined increment size; false otherwise, in which
* case the increment is totally an in memory construct.
*/
public boolean applyIncrementSizeToSourceValues();
}