views/pdo_cache_backend.php

   1 <?php
   2 // Hoplite
   3 // Copyright (c) 2013 Blue Static
   4 //
   5 // This program is free software: you can redistribute it and/or modify it
   6 // under the terms of the GNU General Public License as published by the Free
   7 // Software Foundation, either version 3 of the License, or any later version.
   8 //
   9 // This program is distributed in the hope that it will be useful, but WITHOUT
  10 // ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 // FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12 // more details.
  13 //
  14 // You should have received a copy of the GNU General Public License along with
  15 // this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 namespace hoplite\views;
  18
  19 require_once HOPLITE_ROOT . '/views/cache_backend.php';
  20
  21 /*!
  22   An instance of CacheBackend that stores compiled templates in a database
  23   table accessed through a PDO object.
  24 */
  25 class PDOCacheBackend implements CacheBackend
  26 {
  27   /*! @var \PDO The dat abase to use. */
  28   protected $db = NULL;
  29
  30   /*! @var \PDOStatement Used to query for cached templates. */
  31   protected $fetch_statement = NULL;
  32
  33   /*! @var \PDOStatement Used to insert new templates. */
  34   protected $insert_statement = NULL;
  35
  36   /*! @var \PDOStatement Used to expire out-of-date templates. */
  37   protected $delete_statement = NULL;
  38
  39   /*! @var string Base query for a multi-fetch operation. */
  40   protected $fetch_multi_query = "";
  41
  42   /*!
  43     Constructor that prepares the database statements.
  44
  45     @param \PDO The connected database object.
  46     @param string Name of the database table to store templates in.
  47     @param string Column in which the template name is stored.
  48     @param string Column in which the template data is stored.
  49     @param string Column in which the template last modified time is stored.
  50   */
  51   public function __construct(\PDO $db,
  52                               $table_name,
  53                               $name_column_name = 'name',
  54                               $data_column_name = 'template',
  55                               $timestamp_column_name = 'timestamp')
  56   {
  57     $this->db = $db;
  58
  59     $this->fetch_statement = $db->Prepare("
  60         SELECT `$data_column_name` AS template,
  61             `$timestamp_column_name` AS timestamp
  62         FROM $table_name
  63         WHERE `$name_column_name` IN (:name)
  64     ");
  65
  66     $this->insert_statement = $db->Prepare("
  67         INSERT INTO `$table_name`
  68             (`$name_column_name`, `$data_column_name`, `$timestamp_column_name`)
  69         VALUES
  70             (:name, :template, :timestamp)
  71     ");
  72
  73     $this->delete_statement = $db->Prepare("
  74         DELETE FROM `$table_name`
  75         WHERE `$name_column_name` = :name
  76     ");
  77
  78     $this->fetch_multi_query = "
  79         SELECT `$name_column_name` AS name,
  80             `$data_column_name` AS template,
  81             `$timestamp_column_name` AS timestamp
  82         FROM $table_name
  83         WHERE `$name_column_name` IN ";
  84   }
  85
  86   public function GetTemplateDataForName($name, $modification_time)
  87   {
  88     $this->fetch_statement->Execute(array('name' => $name));
  89     $tpl = $this->fetch_statement->FetchObject();
  90     if (!$tpl)
  91       return NULL;
  92
  93     if ($tpl->timestamp < $modification_time) {
  94       $this->delete_statement->Execute(array('name' => $name));
  95       return NULL;
  96     }
  97
  98     return $tpl->template;
  99   }
 100
 101   public function StoreCompiledTemplate($name, $modification_time, $data)
 102   {
 103     $this->insert_statement->Execute(array(
 104         'name'      => $name,
 105         'timestamp' => $modification_time,
 106         'template'  => $data,
 107     ));
 108   }
 109
 110   public function GetMultipleTemplates(Array $fetch_templates)
 111   {
 112     $placeholders = array_fill(0, count($fetch_templates), '?');
 113     $stmt = $this->db->Prepare($this->fetch_multi_query . '(' . implode(',', $placeholders) . ')');
 114     $stmt->Execute(array_keys($fetch_templates));
 115
 116     $templates = array();
 117     while (($template = $stmt->FetchObject())) {
 118       if ($template->timestamp >= $fetch_templates[$template->name])
 119         $templates[$template->name] = $template->template;
 120     }
 121     return $templates;
 122   }
 123 }