GlobalParameter.java

/**
 * Copyright © 2013 enioka. All rights reserved
 * Authors: Marc-Antoine GOUILLART (marc-antoine.gouillart@enioka.com)
 *          Pierre COPPEE (pierre.coppee@enioka.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 com.enioka.jqm.model;

import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

import com.enioka.jqm.jdbc.DatabaseException;
import com.enioka.jqm.jdbc.DbConn;
import com.enioka.jqm.jdbc.NoResultException;
import com.enioka.jqm.jdbc.QueryResult;

/**
 * <strong>Not part of any API - this an internal JQM class and may change without notice.</strong> <br>
 * Persistence class for storing parameters related to the whole JQM cluster (parameters related to a single engine are stored inside
 * {@link Node}).<br>
 * Parameters are simple key/value string pairs.
 */
public class GlobalParameter implements Serializable
{
    private static final long serialVersionUID = 2619971486012565203L;

    private Integer id;
    private String key;
    private String value;
    private Calendar lastModified;

    /**
     * The key (name) of the parameter. Most parameter keys are unique, but not all so there is no unique constraint inside the database.
     * This is the field used for retrieving {@link GlobalParameter}s.<br>
     * Max length is 50.
     */
    public String getKey()
    {
        return key;
    }

    /**
     * See {@link #getKey()}
     */
    public void setKey(String key)
    {
        this.key = key;
    }

    /**
     * Value of the parameter. Its interpretation depends on the key.<br>
     * Max length is 1000.
     */
    public String getValue()
    {
        return value;
    }

    /**
     * See {@link #getValue()}
     */
    public void setValue(String value)
    {
        this.value = value;
    }

    /**
     * A technical ID without any meaning. Generated by the database.
     */
    public Integer getId()
    {
        return id;
    }

    /**
     * When the object was last modified. Read only.
     */
    public Calendar getLastModified()
    {
        return lastModified;
    }

    /**
     * See {@link #getLastModified()}
     */
    protected void setLastModified(Calendar lastModified)
    {
        this.lastModified = lastModified;
    }

    /**
     * Create a new GP entry in the database. No commit performed.
     */
    public static GlobalParameter create(DbConn cnx, String key, String value)
    {
        QueryResult r = cnx.runUpdate("globalprm_insert", key, value);
        GlobalParameter res = new GlobalParameter();
        res.id = r.getGeneratedId();
        res.key = key;
        res.value = value;
        return res;
    }

    public static List<GlobalParameter> select(DbConn cnx, String query_key, Object... args)
    {
        List<GlobalParameter> res = new ArrayList<GlobalParameter>();
        try
        {
            ResultSet rs = cnx.runSelect(query_key, args);
            while (rs.next())
            {
                GlobalParameter tmp = new GlobalParameter();

                tmp.id = rs.getInt(1);
                tmp.key = rs.getString(2);
                tmp.value = rs.getString(3);
                Calendar c = Calendar.getInstance();
                c.setTimeInMillis(rs.getTimestamp(4).getTime());
                tmp.lastModified = c;

                res.add(tmp);
            }
        }
        catch (SQLException e)
        {
            throw new DatabaseException(e);
        }
        return res;
    }

    /**
     * Retrieve the value of a single-valued parameter.
     * 
     * @param key
     * @param defaultValue
     * @param cnx
     */
    public static String getParameter(DbConn cnx, String key, String defaultValue)
    {
        try
        {
            return cnx.runSelectSingle("globalprm_select_by_key", 3, String.class, key);
        }
        catch (NoResultException e)
        {
            return defaultValue;
        }
    }

    public static void setParameter(DbConn cnx, String key, String value)
    {
        QueryResult qr = cnx.runUpdate("globalprm_update_value_by_key", value, key);
        if (qr.nbUpdated == 0)
        {
            create(cnx, key, value);
        }
    }
}