/*
 * Copyright (C) 2006 Alfresco, Inc.
 *
 * Licensed under the Mozilla Public License version 1.1 
 * with a permitted attribution clause. You may obtain a
 * copy of the License at
 *
 *   http://www.alfresco.org/legal/license.txt
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the
 * License.
 */

package org.alfresco.repo.avm;

/**
 * This is a helper class that knows how to issue identifiers.
 * @author britt
 */
public class Issuer
{
    /**
     * The next number to issue.
     */
    private long fNext;
    
    /**
     * The name of this issuer.
     */
    private String fName;
    
    /**
     * The transactional wrapper.
     */
    private RetryingTransactionHelper fTransaction;
    
    /**
     * Default constructor.
     */
    public Issuer()
    {
    }
    
    /**
     * Set the name of this issuer. For Spring.
     * @param name The name to set.
     */
    public void setName(String name)
    {
        fName = name;
    }
    
    /**
     * Set the transactional wrapper.
     * @param retryingTransaction The transactional wrapper.
     */
    public void setRetryingTransaction(RetryingTransactionHelper retryingTransaction)
    {
        fTransaction = retryingTransaction;
    }
    
    /**
     * After the database is up, get our value.
     */
    public void init()
    {
        class TxnCallback implements RetryingTransactionCallback 
        {
            public Long value;
            
            public void perform()
            {
                value = AVMContext.fgInstance.fIssuerDAO.getIssuerValue(fName);
            }
        };
        TxnCallback doit = new TxnCallback();
        fTransaction.perform(doit, false);
        if (doit.value == null)
        {
            fNext = 0L;
        }
        else
        {
            fNext = doit.value + 1;
        }
    }
    
    /**
     * Issue the next number.
     * @return A serial number.
     */
    public synchronized long issue()
    {
        return fNext++;
    }
}