# DataSourceRepositoryHolder.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.synapse.commons.datasource;

    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.synapse.commons.SynapseCommonsException;
    import org.apache.synapse.commons.datasource.factory.DataSourceInformationRepositoryFactory;

    import java.util.Properties;

    /**
     * Holder for the DataSourceRepository
     */
    @SuppressWarnings({"UnusedDeclaration"})
    public class DataSourceRepositoryHolder {

        private static final Log log = LogFactory.getLog(DataSourceRepositoryHolder.class);

        private static final DataSourceRepositoryHolder DATA_SOURCE_REPOSITORY_HOLDER
                = new DataSourceRepositoryHolder();

        private DataSourceInformationRepository dataSourceInformationRepository;

        private DataSourceRepositoryManager dataSourceRepositoryManager;

        private RepositoryBasedDataSourceFinder repositoryBasedDataSourceFinder;

        private boolean initialized = false;

        private DataSourceRepositoryHolder() {
        }

        public static DataSourceRepositoryHolder getInstance() {
            return DATA_SOURCE_REPOSITORY_HOLDER;
        }

        /**
         * Initialize DataSourceInformationRepository.
         *
         * @param repository to be initialized
         * @param properties DataSources configuration properties
         */
        public void init(DataSourceInformationRepository repository, Properties properties) {

            if (initialized) {
                if (log.isDebugEnabled()) {
                    log.debug("Data source repository holder has already been initialized.");
                }
                return;
            }

            if (log.isDebugEnabled()) {
                log.debug("Initializing the data source repository holder");
            }

            DataSourceInformationRepositoryListener repositoryListener = null;
            if (repository != null) {
                repositoryListener = repository.getRepositoryListener();
            }

            if (repositoryListener == null) {
                repositoryListener = new DataSourceRepositoryManager(
                        new InMemoryDataSourceRepository(),
                        new JNDIBasedDataSourceRepository());
                if (repository != null) {
                    repository.setRepositoryListener(repositoryListener);
                }
            }

            if (repositoryListener instanceof DataSourceRepositoryManager) {
                dataSourceRepositoryManager = (DataSourceRepositoryManager) repositoryListener;
                repositoryBasedDataSourceFinder = new RepositoryBasedDataSourceFinder();
                repositoryBasedDataSourceFinder.init(dataSourceRepositoryManager);
            }

            if (repository == null) {
                repository =
                        DataSourceInformationRepositoryFactory.createDataSourceInformationRepository(
                                repositoryListener, properties);
            } else {
                DataSourceInformationRepositoryFactory.setupDataSourceInformationRepository(
                        repository, properties);
            }
            dataSourceInformationRepository = repository;
            initialized = true;
        }

        public DataSourceInformationRepository getDataSourceInformationRepository() {
            assertInitialized();
            return dataSourceInformationRepository;
        }

        private void assertInitialized() {
            if (!initialized) {
                String msg = "Data source repository holder has not been initialized";
                log.error(msg);
                throw new SynapseCommonsException(msg);
            }
        }

        public boolean isInitialized() {
            return initialized;
        }

        public DataSourceRepositoryManager getDataSourceRepositoryManager() {
            assertInitialized();
            return dataSourceRepositoryManager;
        }

        public RepositoryBasedDataSourceFinder getRepositoryBasedDataSourceFinder() {
            assertInitialized();
            return repositoryBasedDataSourceFinder;
        }
    }