/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
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/**
 * 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.
 * <p/>
 * Optimizers work on constructor injection.  They should provide
 * a constructor with the following arguments <ol>
 * <li>java.lang.Class - The return type for the generated values</li>
 * <li>int - The increment size</li>
 * </ol>
 *
 * @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.
Params:
callback – Callback to access the underlying value source.
Returns:
The generated identifier value./**
	 * 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.
Returns:
The last value we obtained from the underlying source;
null indicates we have not yet consulted with the source./**
	 * 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.
Returns:
The increment size./**
	 * 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?
Returns:
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./**
	 * 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();
}