KeyGeneratorTask.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2012, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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 software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.jboss.capedwarf.cluster;

import org.infinispan.AdvancedCache;
import org.jboss.capedwarf.common.infinispan.NewTxTask;

/**
 * Entity key id generator taks.
 *
 * @author <a href="mailto:ales.justin@jboss.org">Ales Justin</a>
 */
public class KeyGeneratorTask extends NewTxTask<String, Long, Long> {
    private final String sequenceName;
    private final long allocationSize;
    private final long initialValue;

    public KeyGeneratorTask(String sequenceName, long allocationSize) {
        this(sequenceName, allocationSize, 1L);
    }

    public KeyGeneratorTask(String sequenceName, long allocationSize, long initialValue) {
        this.sequenceName = sequenceName;
        this.allocationSize = allocationSize;
        this.initialValue = initialValue;
    }

    protected Long callInTx() throws Exception {
        final AdvancedCache<String, Long> ac = getCache().getAdvancedCache();
        final String cacheKey = sequenceName;
        
        if (ac.lock(cacheKey) == false)
            throw new IllegalArgumentException("Cannot get a lock on id generator for " + cacheKey);

        Long nextId = ac.get(cacheKey);
        if (nextId == null)
            nextId = initialValue;

        ac.put(cacheKey, nextId + allocationSize);

        return nextId;
    }
}