org.hibernate.id.enhanced.LegacyHiLoAlgorithmOptimizer Maven / Gradle / Ivy

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2013, 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 java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.hibernate.HibernateException;
import org.hibernate.id.IntegralDataTypeHolder;

import org.jboss.logging.Logger;

/**
 * Slight variation from {@link HiLoOptimizer}, maintaining compatibility with the values generated by the
 * legacy Hibernate hilo based generators.
 *
 * @author Steve Ebersole
 */
public class LegacyHiLoAlgorithmOptimizer extends AbstractOptimizer {
	private static final Logger log = Logger.getLogger( LegacyHiLoAlgorithmOptimizer.class );

	private final long initialMaxLo;

	private static class GenerationState {
		private long maxLo;
		private long lo;
		private IntegralDataTypeHolder hi;

		private IntegralDataTypeHolder lastSourceValue;
		private IntegralDataTypeHolder value;
	}

	/**
	 * Constructs a LegacyHiLoAlgorithmOptimizer
	 *
	 * @param returnClass The Java type of the values to be generated
	 * @param incrementSize The increment size.
	 */
	public LegacyHiLoAlgorithmOptimizer(Class returnClass, int incrementSize) {
		super( returnClass, incrementSize );
		if ( incrementSize < 1 ) {
			throw new HibernateException( "increment size cannot be less than 1" );
		}
		if ( log.isTraceEnabled() ) {
			log.tracev( "Creating hilo optimizer (legacy) with [incrementSize={0}; returnClass={1}]", incrementSize, returnClass.getName() );
		}
		initialMaxLo = incrementSize;
	}

	@Override
	public synchronized Serializable generate(AccessCallback callback) {
		final GenerationState generationState = locateGenerationState( callback.getTenantIdentifier() );

		if ( generationState.lo > generationState.maxLo ) {
			generationState.lastSourceValue = callback.getNextValue();
			generationState.lo = generationState.lastSourceValue.eq( 0 ) ? 1 : 0;
			generationState.hi = generationState.lastSourceValue.copy().multiplyBy( generationState.maxLo + 1 );
		}
		generationState.value = generationState.hi.copy().add( generationState.lo++ );
		return generationState.value.makeValue();
	}

	private GenerationState noTenantState;
	private Map tenantSpecificState;

	private GenerationState locateGenerationState(String tenantIdentifier) {
		if ( tenantIdentifier == null ) {
			if ( noTenantState == null ) {
				noTenantState = createGenerationState();
			}
			return noTenantState;
		}
		else {
			GenerationState state;
			if ( tenantSpecificState == null ) {
				tenantSpecificState = new ConcurrentHashMap();
				state = createGenerationState();
				tenantSpecificState.put( tenantIdentifier, state );
			}
			else {
				state = tenantSpecificState.get( tenantIdentifier );
				if ( state == null ) {
					state = createGenerationState();
					tenantSpecificState.put( tenantIdentifier, state );
				}
			}
			return state;
		}
	}

	private GenerationState createGenerationState() {
		final GenerationState state = new GenerationState();
		state.maxLo = initialMaxLo;
		state.lo = initialMaxLo + 1;
		return state;
	}

	private GenerationState noTenantGenerationState() {
		if ( noTenantState == null ) {
			throw new IllegalStateException( "Could not locate previous generation state for no-tenant" );
		}
		return noTenantState;
	}

	@Override
	public synchronized IntegralDataTypeHolder getLastSourceValue() {
		return noTenantGenerationState().lastSourceValue.copy();
	}

	@Override
	public boolean applyIncrementSizeToSourceValues() {
		return false;
	}

	/**
	 * Getter for property 'lastValue'.
	 * 
	 * Exposure intended for testing purposes.
	 *
	 * @return Value for property 'lastValue'.
	 */
	@SuppressWarnings( {"UnusedDeclaration"})
	public synchronized IntegralDataTypeHolder getLastValue() {
		return noTenantGenerationState().value;
	}
}