source: Dev/branches/cakephp/cake/libs/model/connection_manager.php @ 126

<?php
/**
 * Datasource connection manager
 *
 * Provides an interface for loading and enumerating connections defined in app/config/database.php
 *
 * PHP versions 4 and 5
 *
 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
 * Copyright 2005-2011, Cake Software Foundation, Inc. (http://cakefoundation.org)
 *
 * Licensed under The MIT License
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright 2005-2011, Cake Software Foundation, Inc. (http://cakefoundation.org)
 * @link          http://cakephp.org CakePHP(tm) Project
 * @package       cake
 * @subpackage    cake.cake.libs.model
 * @since         CakePHP(tm) v 0.10.x.1402
 * @license       MIT License (http://www.opensource.org/licenses/mit-license.php)
 */
require LIBS . 'model' . DS . 'datasources' . DS . 'datasource.php';
include_once CONFIGS . 'database.php';

/**
 * Manages loaded instances of DataSource objects
 *
 * @package       cake
 * @subpackage    cake.cake.libs.model
 */
class ConnectionManager extends Object {

/**
 * Holds a loaded instance of the Connections object
 *
 * @var DATABASE_CONFIG
 * @access public
 */
        var $config = null;

/**
 * Holds instances DataSource objects
 *
 * @var array
 * @access protected
 */
        var $_dataSources = array();

/**
 * Contains a list of all file and class names used in Connection settings
 *
 * @var array
 * @access protected
 */
        var $_connectionsEnum = array();

/**
 * Constructor.
 *
 */
        function __construct() {
                if (class_exists('DATABASE_CONFIG')) {
                        $this->config =& new DATABASE_CONFIG();
                        $this->_getConnectionObjects();
                }
        }

/**
 * Gets a reference to the ConnectionManger object instance
 *
 * @return object Instance
 * @access public
 * @static
 */
        function &getInstance() {
                static $instance = array();

                if (!$instance) {
                        $instance[0] =& new ConnectionManager();
                }

                return $instance[0];
        }

/**
 * Gets a reference to a DataSource object
 *
 * @param string $name The name of the DataSource, as defined in app/config/database.php
 * @return object Instance
 * @access public
 * @static
 */
        function &getDataSource($name) {
                $_this =& ConnectionManager::getInstance();

                if (!empty($_this->_dataSources[$name])) {
                        $return =& $_this->_dataSources[$name];
                        return $return;
                }

                if (empty($_this->_connectionsEnum[$name])) {
                        trigger_error(sprintf(__("ConnectionManager::getDataSource - Non-existent data source %s", true), $name), E_USER_ERROR);
                        $null = null;
                        return $null;
                }
                $conn = $_this->_connectionsEnum[$name];
                $class = $conn['classname'];

                if ($_this->loadDataSource($name) === null) {
                        trigger_error(sprintf(__("ConnectionManager::getDataSource - Could not load class %s", true), $class), E_USER_ERROR);
                        $null = null;
                        return $null;
                }
                $_this->_dataSources[$name] =& new $class($_this->config->{$name});
                $_this->_dataSources[$name]->configKeyName = $name;

                $return =& $_this->_dataSources[$name];
                return $return;
        }

/**
 * Gets the list of available DataSource connections
 *
 * @return array List of available connections
 * @access public
 * @static
 */
        function sourceList() {
                $_this =& ConnectionManager::getInstance();
                return array_keys($_this->_dataSources);
        }

/**
 * Gets a DataSource name from an object reference.
 *
 * **Warning** this method may cause fatal errors in PHP4.
 *
 * @param object $source DataSource object
 * @return string Datasource name, or null if source is not present
 *    in the ConnectionManager.
 * @access public
 * @static
 */
        function getSourceName(&$source) {
                $_this =& ConnectionManager::getInstance();
                foreach ($_this->_dataSources as $name => $ds) {
                        if ($ds == $source) {
                                return $name;
                        }
                }
                return '';
        }

/**
 * Loads the DataSource class for the given connection name
 *
 * @param mixed $connName A string name of the connection, as defined in app/config/database.php,
 *                        or an array containing the filename (without extension) and class name of the object,
 *                        to be found in app/models/datasources/ or cake/libs/model/datasources/.
 * @return boolean True on success, null on failure or false if the class is already loaded
 * @access public
 * @static
 */
        function loadDataSource($connName) {
                $_this =& ConnectionManager::getInstance();

                if (is_array($connName)) {
                        $conn = $connName;
                } else {
                        $conn = $_this->_connectionsEnum[$connName];
                }

                if (class_exists($conn['classname'])) {
                        return false;
                }

                if (!empty($conn['parent'])) {
                        $_this->loadDataSource($conn['parent']);
                }

                $conn = array_merge(array('plugin' => null, 'classname' => null, 'parent' => null), $conn);
                $class = "{$conn['plugin']}.{$conn['classname']}";

                if (!App::import('Datasource', $class, !is_null($conn['plugin']))) {
                        trigger_error(sprintf(__('ConnectionManager::loadDataSource - Unable to import DataSource class %s', true), $class), E_USER_ERROR);
                        return null;
                }
                return true;
        }

/**
 * Return a list of connections
 *
 * @return array An associative array of elements where the key is the connection name
 *               (as defined in Connections), and the value is an array with keys 'filename' and 'classname'.
 * @access public
 * @static
 */
        function enumConnectionObjects() {
                $_this =& ConnectionManager::getInstance();

                return $_this->_connectionsEnum;
        }

/**
 * Dynamically creates a DataSource object at runtime, with the given name and settings
 *
 * @param string $name The DataSource name
 * @param array $config The DataSource configuration settings
 * @return object A reference to the DataSource object, or null if creation failed
 * @access public
 * @static
 */
        function &create($name = '', $config = array()) {
                $_this =& ConnectionManager::getInstance();

                if (empty($name) || empty($config) || array_key_exists($name, $_this->_connectionsEnum)) {
                        $null = null;
                        return $null;
                }
                $_this->config->{$name} = $config;
                $_this->_connectionsEnum[$name] = $_this->__connectionData($config);
                $return =& $_this->getDataSource($name);
                return $return;
        }

/**
 * Gets a list of class and file names associated with the user-defined DataSource connections
 *
 * @return void
 * @access protected
 * @static
 */
        function _getConnectionObjects() {
                $connections = get_object_vars($this->config);

                if ($connections != null) {
                        foreach ($connections as $name => $config) {
                                $this->_connectionsEnum[$name] = $this->__connectionData($config);
                        }
                } else {
                        $this->cakeError('missingConnection', array(array('code' => 500, 'className' => 'ConnectionManager')));
                }
        }

/**
 * Returns the file, class name, and parent for the given driver.
 *
 * @return array An indexed array with: filename, classname, plugin and parent
 * @access private
 */
        function __connectionData($config) {
                if (!isset($config['datasource'])) {
                        $config['datasource'] = 'dbo';
                }
                $filename = $classname = $parent = $plugin = null;

                if (!empty($config['driver'])) {
                        $parent = $this->__connectionData(array('datasource' => $config['datasource']));
                        $parentSource = preg_replace('/_source$/', '', $parent['filename']);

                        list($plugin, $classname) = pluginSplit($config['driver']);
                        if ($plugin) {
                                $source = Inflector::underscore($classname);
                        } else {
                                $source = $parentSource . '_' . $config['driver'];
                                $classname = Inflector::camelize(strtolower($source));
                        }
                        $filename = $parentSource . DS . $source;
                } else {
                        list($plugin, $classname) = pluginSplit($config['datasource']);
                        if ($plugin) {
                                $filename = Inflector::underscore($classname);
                        } else {
                                $filename = Inflector::underscore($config['datasource']);
                        }
                        if (substr($filename, -7) != '_source') {
                                $filename .= '_source';
                        }
                        $classname = Inflector::camelize(strtolower($filename));
                }
                return compact('filename', 'classname', 'parent', 'plugin');
        }

/**
 * Destructor.
 *
 * @access private
 */
        function __destruct() {
                if (Configure::read('Session.save') == 'database' && function_exists('session_write_close')) {
                        session_write_close();
                }
        }
}