java/broker/src/main/java/org/apache/qpid/server/configuration/BrokerConfigurationStoreCreator.java

/*
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.qpid.server.configuration;

import java.util.HashMap;
import java.util.Map;

import org.apache.qpid.server.configuration.store.JsonConfigurationEntryStore;
import org.apache.qpid.server.plugin.QpidServiceLoader;

/**
 * A helper class responsible for creation and opening of broker store.
 */
public class BrokerConfigurationStoreCreator
{
    /**
     * URL to resource containing broker default configuration
     */
    public static final String DEFAULT_INITIAL_STORE_LOCATION = BrokerConfigurationStoreCreator.class.getClassLoader()
            .getResource("initial-store.json").toExternalForm();

    private Map<String, ConfigurationStoreFactory> _factories = new HashMap<String, ConfigurationStoreFactory>();

    public BrokerConfigurationStoreCreator()
    {
        QpidServiceLoader<ConfigurationStoreFactory> serviceLoader = new QpidServiceLoader<ConfigurationStoreFactory>();
        Iterable<ConfigurationStoreFactory> configurationStoreFactories = serviceLoader
                .instancesOf(ConfigurationStoreFactory.class);
        for (ConfigurationStoreFactory storeFactory : configurationStoreFactories)
        {
            String type = storeFactory.getStoreType();
            ConfigurationStoreFactory factory = _factories.put(type.toLowerCase(), storeFactory);
            if (factory != null)
            {
                throw new IllegalStateException("ConfigurationStoreFactory with type name '" + type
                        + "' is already registered using class '" + factory.getClass().getName() + "', can not register class '"
                        + storeFactory.getClass().getName() + "'");
            }
        }
    }

    /**
     * Create broker configuration store for a given store location, store type, initial store location and initial store type
     *
     * @param storeLocation store location
     * @param storeType store type
     * @param initialStoreLocation initial store location
     * @param initialStoreType initial store type
     * @return store instance opened at given store location
     * @throws IllegalConfigurationException if store type is unknown
     */
    public ConfigurationEntryStore createStore(String storeLocation, String storeType, String initialStoreLocation,
            String initialStoreType)
    {
        ConfigurationEntryStore store = createStore(storeType);
        if (initialStoreLocation == null)
        {
            initialStoreLocation = DEFAULT_INITIAL_STORE_LOCATION;
            initialStoreType = JsonConfigurationEntryStore.STORE_TYPE;
        }
        if (storeType.equals(initialStoreType))
        {
            store.open(storeLocation, initialStoreLocation);
        }
        else
        {
            ConfigurationEntryStore initialStore = createStore(initialStoreType);
            initialStore.open(initialStoreLocation);
            store.open(storeLocation, initialStore);
        }
        return store;
    }

    private ConfigurationEntryStore createStore(String storeType)
    {
        ConfigurationStoreFactory factory = _factories.get(storeType.toLowerCase());
        if (factory == null)
        {
            throw new IllegalConfigurationException("Unknown store type: " + storeType);
        }
        return factory.createStore();
    }

}