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<?php
/**
* DbCache Class.
*
* @package Silla.IO
* @subpackage Core\Modules\DB
* @author Kalin Stefanov <kalin@athlonsofia.com>
* @copyright Copyright (c) 2015, Silla.io
* @license http://opensource.org/licenses/GPL-3.0 GNU General Public License, version 3.0 (GPLv3)
*/
namespace Core\Modules\DB;
use Core;
/**
* DbCache Class Definition. Singleton class for handling the database cache.
*/
final class DbCache
{
/**
* Whether there is a schema or not.
*
* @var boolean
* @access private
*/
private $hasSchema = false;
/**
* Stores the queries cache.
*
* @var array
* @access private
*/
public $cache = array();
/**
* Stores tables schema.
*
* @var array
* @access private
*/
private $schema = array();
/**
* Stores the state of the tables(if the table has been changed, after cached query).
*
* @var array
* @access private
*/
private $tables = array();
/**
* Stores the prepared database statements.
*
* @var array
* @access private
*/
private $statements = array();
/**
* Data source name.
*
* @var array Array containing the credentials.
*/
private $dsn;
/**
* Initialize DB Cache.
*
* @param array $dsn Data source name.
*
* @uses setSchema()
*/
public function __construct(array $dsn)
{
$this->dsn = $dsn;
$names = Core\DB()->getTables($this->dsn['name']);
if (empty($names)) {
return;
}
foreach ($names as $tableName) {
$schemaMeta = $this->getSchemaMeta($tableName);
/* Cache the schema for the current execution of the script */
$this->setSchema($tableName, $schemaMeta);
}
$this->hasSchema = true;
}
/**
* Cloning of DbCache is disallowed.
*
* @access public
*
* @return void
*/
public function __clone()
{
trigger_error(__CLASS__ . ' cannot be cloned! It is a singleton.', E_USER_ERROR);
}
/**
* Set method.
*
* @param string $attr Attribute name.
* @param mixed $val Attribute value.
*
* @return void
*/
public function __set($attr, $val)
{
$this->{$attr} = $val;
}
/**
* Get method.
*
* @param string $attr Attribute name.
*
* @return mixed
*/
public function __get($attr)
{
return $this->{$attr};
}
/**
* Cache a query and its result.
*
* @param string $table Table name.
* @param string $query SQL query.
* @param array $result Result array.
*
* @access public
*
* @return void
*/
public function setCache($table, $query, array $result)
{
if (!$this->cache[$table]) {
$this->cache[$table] = array();
}
$this->cache[$table][$query] = $result;
}
/**
* Get the result of a cached query, or return the whole cache.
*
* @param string $table Table name.
* @param string $query Query string(optional).
*
* @access public
*
* @return array
*/
public function getCache($table, $query = null)
{
if ($query) {
return $this->cache[$table][$query];
}
if (!(isset($this->cache[$table]) && $this->cache[$table])) {
$this->cache[$table] = array();
}
return $this->cache[$table];
}
/**
* Clears the cache for a given table.
*
* @param string $table Table name.
*
* @return void
*/
public function clearCache($table)
{
unset($this->cache[$table]);
}
/**
* Get the state of a table.
*
* @param string $name Name of the table.
*
* @access public
*
* @return boolean
*/
public function getTable($name)
{
return $this->tables[$name];
}
/**
* Get a database statement.
*
* @param string $query It's used for a key.
*
* @access public
*
* @return object
*/
public function getStatement($query)
{
return $this->statements[$query];
}
/**
* Set a table schema.
*
* @param string $table Name of the table.
* @param array $value Schema data.
*
* @access private
*
* @return void
*/
private function setSchema($table, array $value)
{
$this->schema[$table] = $value;
}
/**
* Get the table schema.
*
* @param string $table Name of the table.
*
* @access public
*
* @return array
*/
public function getSchema($table)
{
return isset($this->schema[$this->dsn['tables_prefix'] . $table]) ?
$this->schema[$this->dsn['tables_prefix'] . $table] : array();
}
/**
* Get table meta information from cache or extract it, if missing.
*
* @param string $tableName Name of the table.
*
* @uses Core\Cache()
* @uses extractSchemaMeta()
*
* @return array
*/
private function getSchemaMeta($tableName)
{
if (Core\Config()->CACHE['db_schema']) {
$schemaMeta = Core\Cache()->fetch($tableName);
if (is_null($schemaMeta)) {
$schemaMeta = $this->extractSchemaMeta($tableName);
Core\Cache()->store($tableName, $schemaMeta);
}
} else {
$schemaMeta = $this->extractSchemaMeta($tableName);
}
return $schemaMeta;
}
/**
* Retrieve meta information about supplied database table.
*
* @param string $tableName Name of the table.
*
* @throws \LogicException Error extracting schema meta information.
* @access private
* @uses Core\DB()
* @uses associateType()
*
* @return array
*/
private function extractSchemaMeta($tableName)
{
$fields_meta = array();
$results = Core\DB()->getTableSchema($tableName, $this->dsn['name']);
foreach ($results as $result) {
$fields_meta[$result['COLUMN_NAME']]['type'] = $this->associateType($result['DATA_TYPE']);
$fields_meta[$result['COLUMN_NAME']]['is_null'] = $result['IS_NULLABLE'];
$fields_meta[$result['COLUMN_NAME']]['extra'] = $result['EXTRA'];
$fields_meta[$result['COLUMN_NAME']]['default'] = $result['COLUMN_DEFAULT'];
$fields_meta[$result['COLUMN_NAME']]['unique'] = $result['COLUMN_KEY'] == 'UNI';
/* If the field is string, varchar, text etc. add the max length of this field into the schema */
if ('string' === $fields_meta[$result['COLUMN_NAME']]['type']) {
$fields_meta[$result['COLUMN_NAME']]['length'] = $result['CHARACTER_MAXIMUM_LENGTH'];
}
if ('enum' === $fields_meta[$result['COLUMN_NAME']]['type'] && isset($result['COLUMN_TYPE'])) {
$fields_meta[$result['COLUMN_NAME']]['values'] = explode(
"','",
str_replace(array("enum('", "')", "''"), array('', '', "'"), $result['COLUMN_TYPE'])
);
}
}
if (empty($fields_meta)) {
throw new \LogicException('Error extracting schema meta information.');
}
return $fields_meta;
}
/**
* Associate the field type with specific value used in the queries.
*
* @param string $type Field type.
*
* @access private
*
* @return string
*/
private function associateType($type)
{
switch ($type) {
case 'tinyint':
case 'smallint':
case 'mediumint':
case 'int':
case 'bigint':
return 'int';
case 'double':
case 'float':
case 'decimal':
return 'double';
case 'time':
case 'date':
case 'timestamp':
return 'date';
case 'datetime':
return 'datetime';
case 'enum':
return 'enum';
default:
return 'string';
}
}
}