org.neo4j.kernel.configuration.BaseConfigurationMigrator Maven / Gradle / Ivy

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/**
 * Copyright (c) 2002-2013 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.kernel.configuration;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.neo4j.kernel.impl.util.StringLogger;

/**
 * A basic approach to implementing configuration migrations.
 * This applies migrations in both directions, meaning that you
 * can still continue to both read and write with the old configuration
 * value.
 */
public class BaseConfigurationMigrator implements ConfigurationMigrator {

    public static interface Migration 
    {
        public boolean appliesTo(Map rawConfiguration);

        public Map apply(Map rawConfiguration);
        
        public String getDeprecationMessage();
    }
    
    public static abstract class SpecificPropertyMigration implements Migration
    {

        private String propertyKey;
        private String deprecationMessage;

        public SpecificPropertyMigration(String propertyKey, String deprecationMessage)
        {
            this.propertyKey = propertyKey;
            this.deprecationMessage = deprecationMessage;
        }
        
        public boolean appliesTo(Map rawConfiguration) 
        {
            return rawConfiguration.containsKey(propertyKey);
        }
        
        public Map apply(Map rawConfiguration) 
        {
            String value = rawConfiguration.get(propertyKey);
            rawConfiguration.remove(propertyKey);
            setValueWithOldSetting(value, rawConfiguration);
            return rawConfiguration;
        }
        
        public String getDeprecationMessage()
        {
            return deprecationMessage;
        }
        
        public abstract void setValueWithOldSetting(String value, Map rawConfiguration);
    }
    
    public static class PropertyRenamed extends SpecificPropertyMigration
    {

        private String newKey;

		public PropertyRenamed(String oldKey, String newKey, String deprecationMessage)
        {
            super(oldKey, deprecationMessage);
            this.newKey = newKey;
        }
		
        public void setValueWithOldSetting(String value, Map rawConfiguration)
        {
        	rawConfiguration.put(newKey, value);
        }
    }
    
    public static Migration propertyRenamed(String oldKey, String newKey, String deprecationMessage)
    {
    	return new PropertyRenamed(oldKey, newKey, deprecationMessage);
    }
    
    private List migrations = new ArrayList();
    
    public void add(Migration migration) 
    {
        migrations.add(migration);
    }

    @Override
    public Map apply(Map rawConfiguration, StringLogger log)
    {
        boolean printedDeprecationMessage = false;
        for(Migration migration : migrations) 
        {
            if(migration.appliesTo(rawConfiguration)) 
            {
                if(!printedDeprecationMessage) 
                {
                    printedDeprecationMessage = true;
                    log.logMessage( "WARNING! Deprecated configuration options used. See manual for details" );
                }

                rawConfiguration = migration.apply(rawConfiguration);

                log.logMessage( migration.getDeprecationMessage() );
            }
        }
        return rawConfiguration;
    }
    
}