# JdbcDataSource.java

    /*
    ** Module   : JdbcDataSource.java
    ** Abstract : JDBC data source which wraps a C3P0 pooled data source
    **
    ** Copyright (c) 2019-2025, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --------------------------------Description----------------------------------
    ** 001 ECF 20190902 Created initial version. Establishes a C3P0 pooled data source per database.
    ** 002 GBB 20230512 Logging methods replaced by CentralLogger/ConversionStatus.
    ** 003 RAA 20240423 Modified methods to also include the database configuration.
    **     RAA 20240426 The DataSource is now also based on the tenant's id, not only the database.
    ** 004 OM  20240909 Improved Database API.
    ** 005 OM  20241128 Multi-tenant runtime support: selected the proper persistence context, eventually
    **                  based on [sharedDb] parameter.
    ** 006 AS  20241209 Implemented a retry system for getting connections.
    ** 007 LS  20250321 Remove the dataSource from the sources and close it when it becomes broken.
    */

    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
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    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
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    */

    package com.goldencode.p2j.persist.orm;

    import java.sql.*;
    import java.util.*;
    import java.util.concurrent.*;
    import javax.sql.DataSource;
    import com.goldencode.p2j.persist.*;
    import com.goldencode.p2j.util.logging.*;
    import com.mchange.v2.c3p0.ComboPooledDataSource;
    import com.mchange.v2.resourcepool.ResourcePoolException;

    /**
     * A JDBC data source which wraps a C3P0 pooled data source. Access to pooled data sources is via
     * static methods, and is organized by database.
     */
    class JdbcDataSource
    {
       /** Logger */
       static final CentralLogger log = CentralLogger.get(JdbcDataSource.class.getName());

       /** Concurrent map of instances, keyed by database keys. */
       private static Map<DatabaseKey, JdbcDataSource> sources = new ConcurrentHashMap<>();

       /** Delegate data source */
       private final DataSource dataSource;

       /** Flag indicating whether data source supports batch operations */
       private final boolean batch;

       /**
        * Get a JDBC connection from the pool, creating it if necessary.
        *
        * @param   database
        *          Database with which the connection must be established.
        * @param   cfg
        *          The configuration of the given database.
        * @param   tenantName
        *          The name of the tenant.
        *
        * @return  JDBC connection.
        *
        * @throws  PersistenceException
        *          if there is an error configuring or obtaining the data source or connection.
        */
       static Connection getConnection(Database database, DatabaseConfig cfg, String tenantName)
       throws PersistenceException
       {
          Connection connection = null;
          Exception e = null;
          int retryConnectionCount = 0;
          boolean retry = true;

          while (retry)
          {
             retry = false;
             try
             {
                DataSource ds = getDataSource(database, cfg, tenantName).dataSource;

                // There is a possibility that another thread will throw an
                // InterruptedException at the same time a checkout of a
                // connection is attempted by this thread and it will fail, in this cases,
                // the checkout is retried.
                // It is highly unlikely that all 3 attempts will be interrupted by another thread,
                // but if that happens, we will need to adjust the retryConnectionCount.
                while (connection == null && retryConnectionCount < 3)
                {
                   try
                   {
                      connection = ds.getConnection();
                   }
                   catch (SQLException exc)
                   {
                      e = exc;
                      Throwable cause = exc.getCause();

                      // check if the underlying cause of the exception is a broken resource pool
                      // the c3p0 pool can declare itself "broken" if it fails to obtain a connection and
                      // has the breakAfterAcquireFailure flag enabled.
                      if (cause instanceof ResourcePoolException &&
                          cause.getMessage().equals(DBUtils.BROKEN_POOL_ERROR))
                      {
                         DatabaseKey key = new DatabaseKey(database, tenantName);
                         if (ds instanceof ComboPooledDataSource)
                         {
                            // the broken datasource must be closed manually to release its resources.
                            ((ComboPooledDataSource) ds).close();
                         }
                         // the dataSource is broken, we need to remove it
                         sources.remove(key);

                         // we detected now that the datasource is broken,
                         // but maybe the connection was restored in the meantime
                         // try getting a new one before throwing the PersistenceException
                         retry = true;
                         break;
                      }
                      retryConnectionCount++;
                   }
                }
             }
             catch (PersistenceException exc)
             {
                e = exc;
             }
          }
          if (connection == null)
          {
             throw new PersistenceException(DBUtils.JDBC_CONNECTION_ERROR, e);
          }
          return connection;
       }

       /**
        * Indicate whether the data source represented by the given database object supports batch
        * operations.
        *
        * @param   database
        *          Database for which batch support information is needed.
        *
        * @return  {@code true} if batch operations are supported, else {@code false}.
        *
        * @throws  PersistenceException
        *          if database metadata needs to be queried and there is an error doing so.
        */
       static boolean supportsBatch(Database database)
       throws PersistenceException
       {
          return getDataSource(database, null, null).batch;
       }

       /**
        * Get the JDBC data source for the given database.
        *
        * @param   database
        *          Database object which identifies the data source.
        * @param   cfg
        *          The configuration of the given database.
        * @param   tenantName
        *          The name of the tenant.
        *
        * @return  Data source object.
        *
        * @throws  PersistenceException
        *          if there is an error configuring or obtaining the data source.
        */
       private static JdbcDataSource getDataSource(Database database, DatabaseConfig cfg, String tenantName)
       throws PersistenceException
       {
          DatabaseKey dbKey = new DatabaseKey(database, tenantName);
          JdbcDataSource jds = sources.get(dbKey);

          if (jds == null)
          {
             DataSource dataSource = database.isTemporary()
                                  ? new TempTableDataSourceProvider().getDataSource(database, cfg)
                                  : PooledDataSourceProvider.getInstance().getDataSource(database, cfg, tenantName);
             jds = new JdbcDataSource(dataSource);
             sources.put(dbKey, jds);
          }

          return jds;
       }

       /**
        * Private constructor; all access is via static methods. Reads configuration data from the
        * application directory and constructs the data source accordingly.
        *
        * @param   dataSource
        *          The data source. Note that only the database name is used directly to configure the data
        *          source; all other information is read from the directory or is derived, based on the database
        *          type.
        *
        * @throws  PersistenceException
        *          if there is an error configuring or obtaining the data source.
        */
       private JdbcDataSource(DataSource dataSource)
       throws PersistenceException
       {
          this.dataSource = dataSource;

          try (Connection conn = dataSource.getConnection())
          {
             DatabaseMetaData dbMeta = conn.getMetaData();
             this.batch = dbMeta.supportsBatchUpdates();
          }
          catch (SQLException exc)
          {
             // if an error is encountered when using a c3p0 datasource
             // it needs to be closed manually to release its resources
             if (dataSource instanceof ComboPooledDataSource)
             {
                ((ComboPooledDataSource) dataSource).close();
             }
             throw new PersistenceException("Error querying database metadata", exc);
          }
       }

       /**
        * Class that handles a database key for the {@code sources} map.
        * This involves one component (the database instance) if we are not in multi-tenancy mode,
        * or two components (the database instance and the tenant id) otherwise.
        */
       private static class DatabaseKey
       {
          /** The database instance to work with. */
          private final Database db;

          /** The tenant id. This will be {@code null} if multi-tenancy is not enabled. */
          private final String tenantName;

          /** The hash code for the key. */
          private final int hashCode;

          /**
           * Basic constructor.
           *
           * @param   db
           *          The database instance to work with.
           * @param   tenantName
           *          The name of the tenant.
           */
          private DatabaseKey(Database db, String tenantName)
          {
             this.db = db;
             this.tenantName = tenantName;
             hashCode = tenantName != null                                     ?
                        (37 * 17 + db.hashCode()) * 37 + tenantName.hashCode() :
                        37 * 17 + db.hashCode();
          }

          /**
           * Calculate a hash code for this object.
           *
           * @return  Hash code.
           */
          @Override
          public int hashCode()
          {
             return hashCode;
          }

          /**
           * Test the equality between this instance and another given one.
           *
           * @return  {@code true} if the objects match, {@code false} otherwise.
           */
          @Override
          public boolean equals(Object o)
          {
             if (this == o)
             {
                // Same instance.
                return true;
             }

             if (!(o instanceof DatabaseKey))
             {
                // Impossible to be equivalent.
                return false;
             }

             DatabaseKey that = (DatabaseKey) o;

             if (!this.db.equals(that.db))
             {
                return false;
             }

             if (this.tenantName != null && that.tenantName == null ||
                 this.tenantName == null && that.tenantName != null)
             {
                return false;
             }

             if (this.tenantName == null && that.tenantName == null)
             {
                return true;
             }

             return this.tenantName.equals(that.tenantName);
          }
       }
    }