Club Drupal

<?php

/**

 * @file

 * Definition of views_plugin_cache.

 */

/**

 * @defgroup views_cache_plugins Views cache plugins

 * @{

 * @todo.

 *

 * @see hook_views_plugins()

 */

/**

 * The base plugin to handle caching.

 */

class views_plugin_cache extends views_plugin {

  /**

   * Contains all data that should be written/read from cache.

   */

  var $storage = array();

  /**

   * What table to store data in.

   */

  var $table = 'cache_views_data';

  /**

   * Initialize the plugin.

   *

   * @param $view

   *   The view object.

   * @param $display

   *   The display handler.

   */

  function init(&$view, &$display) {

    $this->view = &$view;

    $this->display = &$display;

    if (is_object($display->handler)) {

      $options = $display->handler->get_option('cache');

      // Overlay incoming options on top of defaults

      $this->unpack_options($this->options, $options);

    }

  }

  /**

   * Return a string to display as the clickable title for the

   * access control.

   */

  function summary_title() {

    return t('Unknown');

  }

  /**

   * Determine the expiration time of the cache type, or NULL if no expire.

   *

   * Plugins must override this to implement expiration.

   *

   * @param $type

   *   The cache type, either 'query', 'result' or 'output'.

   */

   function cache_expire($type) { }

   /**

    * Determine expiration time in the cache table of the cache type

    * or CACHE_PERMANENT if item shouldn't be removed automatically from cache.

    *

    * Plugins must override this to implement expiration in the cache table.

    *

    * @param $type

    *   The cache type, either 'query', 'result' or 'output'.

    */

  function cache_set_expire($type) {

    return CACHE_PERMANENT;

  }

  /**

   * Save data to the cache.

   *

   * A plugin should override this to provide specialized caching behavior.

   */

  function cache_set($type) {

    switch ($type) {

      case 'query':

        // Not supported currently, but this is certainly where we'd put it.

        break;

      case 'results':

        $data = array(

          'result' => $this->view->result,

          'total_rows' => isset($this->view->total_rows) ? $this->view->total_rows : 0,

          'current_page' => $this->view->get_current_page(),

        );

        cache_set($this->get_results_key(), $data, $this->table, $this->cache_set_expire($type));

        break;

      case 'output':

        $this->gather_headers();

        $this->storage['output'] = $this->view->display_handler->output;

        cache_set($this->get_output_key(), $this->storage, $this->table, $this->cache_set_expire($type));

        break;

    }

  }

  /**

   * Retrieve data from the cache.

   *

   * A plugin should override this to provide specialized caching behavior.

   */

  function cache_get($type) {

    $cutoff = $this->cache_expire($type);

    switch ($type) {

      case 'query':

        // Not supported currently, but this is certainly where we'd put it.

        return FALSE;

      case 'results':

        // Values to set: $view->result, $view->total_rows, $view->execute_time,

        // $view->current_page.

        if ($cache = cache_get($this->get_results_key(), $this->table)) {

          if (!$cutoff || $cache->created > $cutoff) {

            $this->view->result = $cache->data['result'];

            $this->view->total_rows = $cache->data['total_rows'];

            $this->view->set_current_page($cache->data['current_page']);

            $this->view->execute_time = 0;

            return TRUE;

          }

        }

        return FALSE;

      case 'output':

        if ($cache = cache_get($this->get_output_key(), $this->table)) {

          if (!$cutoff || $cache->created > $cutoff) {

            $this->storage = $cache->data;

            $this->view->display_handler->output = $cache->data['output'];

            $this->restore_headers();

            return TRUE;

          }

        }

        return FALSE;

    }

  }

  /**

   * Clear out cached data for a view.

   *

   * We're just going to nuke anything related to the view, regardless of display,

   * to be sure that we catch everything. Maybe that's a bad idea.

   */

  function cache_flush() {

    cache_clear_all($this->view->name . ':', $this->table, TRUE);

  }

  /**

   * Post process any rendered data.

   *

   * This can be valuable to be able to cache a view and still have some level of

   * dynamic output. In an ideal world, the actual output will include HTML

   * comment based tokens, and then the post process can replace those tokens.

   *

   * Example usage. If it is known that the view is a node view and that the

   * primary field will be a nid, you can do something like this:

   *

   * <!--post-FIELD-NID-->

   *

   * And then in the post render, create an array with the text that should

   * go there:

   *

   * strtr($output, array('<!--post-FIELD-1-->', 'output for FIELD of nid 1');

   *

   * All of the cached result data will be available in $view->result, as well,

   * so all ids used in the query should be discoverable.

   */

  function post_render(&$output) { }

  /**

   * Start caching javascript, css and other out of band info.

   *

   * This takes a snapshot of the current system state so that we don't

   * duplicate it. Later on, when gather_headers() is run, this information

   * will be removed so that we don't hold onto it.

   */

  function cache_start() {

    $this->storage['head'] = drupal_add_html_head();

    $this->storage['css'] = drupal_add_css();

    $this->storage['js'] = drupal_add_js();

    $this->storage['headers'] = drupal_get_http_header();

  }

  /**

   * Gather out of band data, compare it to what we started with and store the difference.

   */

  function gather_headers() {

    // Simple replacement for head

    if (isset($this->storage['head'])) {

      $this->storage['head'] = str_replace($this->storage['head'], '', drupal_add_html_head());

    }

    else {

      $this->storage['head'] = '';

    }

    // Check if the advanced mapping function of D 7.23 is available.

    $array_mapping_func = function_exists('drupal_array_diff_assoc_recursive') ? 'drupal_array_diff_assoc_recursive' : 'array_diff_assoc';

    // Slightly less simple for CSS:

    $css = drupal_add_css();

    $css_start = isset($this->storage['css']) ? $this->storage['css'] : array();

    $this->storage['css'] = $this->assetDiff($css, $css_start, $array_mapping_func);

    // Get javascript after/before views renders.

    $js = drupal_add_js();

    $js_start = isset($this->storage['js']) ? $this->storage['js'] : array();

    // If there are any differences between the old and the new javascript then

    // store them to be added later.

    $this->storage['js'] = $this->assetDiff($js, $js_start, $array_mapping_func);

    // Special case the settings key and get the difference of the data.

    $settings = isset($js['settings']['data']) ? $js['settings']['data'] : array();

    $settings_start = isset($js_start['settings']['data']) ? $js_start['settings']['data'] : array();

    $this->storage['js']['settings'] = $array_mapping_func($settings, $settings_start);

    // Get difference of HTTP headers.

    $this->storage['headers'] = $array_mapping_func(drupal_get_http_header(), $this->storage['headers']);

  }

  /**

   * Computes the differences between two JS/CSS asset arrays.

   *

   * @param array $assets

   *   The current asset array.

   * @param array $start_assets

   *   The original asset array.

   * @param string $diff_function

   *   The function that should be used for computing the diff.

   *

   * @return array

   *   A CSS or JS asset array that contains all entries that are new/different

   *   in $assets.

   */

  protected function assetDiff(array $assets, array $start_assets, $diff_function) {

    $diff = $diff_function($assets, $start_assets);

    // Cleanup the resulting array since drupal_array_diff_assoc_recursive() can

    // leave half populated arrays behind.

    foreach ($diff as $key => $entry) {

      // If only the weight was different we can remove this entry.

      if (count($entry) == 1 && isset($entry['weight'])) {

        unset($diff[$key]);

      }

      // If there are other differences we override with the latest entry.

      elseif ($entry != $assets[$key]) {

        $diff[$key] = $assets[$key];

      }

    }

    return $diff;

  }

  /**

   * Restore out of band data saved to cache. Copied from Panels.

   */

  function restore_headers() {

    if (!empty($this->storage['head'])) {

      drupal_add_html_head($this->storage['head']);

    }

    if (!empty($this->storage['css'])) {

      foreach ($this->storage['css'] as $args) {

        drupal_add_css($args['data'], $args);

      }

    }

    if (!empty($this->storage['js'])) {

      foreach ($this->storage['js'] as $key => $args) {

        if ($key !== 'settings') {

          drupal_add_js($args['data'], $args);

        }

        else {

          foreach ($args as $setting) {

            drupal_add_js($setting, 'setting');

          }

        }

      }

    }

    if (!empty($this->storage['headers'])) {

      foreach ($this->storage['headers'] as $name => $value) {

        drupal_add_http_header($name, $value);

      }

    }

  }

  function get_results_key() {

    if (!isset($this->_results_key)) {

      $key_data = array();

      foreach (array('exposed_info', 'page', 'sort', 'order', 'items_per_page', 'offset') as $key) {

        if (isset($_GET[$key])) {

          $key_data[$key] = $_GET[$key];

        }

      }

      $this->_results_key = $this->view->name . ':' . $this->display->id . ':results:' . $this->get_cache_key($key_data);

    }

    return $this->_results_key;

  }

  function get_output_key() {

    if (!isset($this->_output_key)) {

      $key_data = array(

        'result' => $this->view->result,

        'theme' => $GLOBALS['theme'],

      );

      $this->_output_key = $this->view->name . ':' . $this->display->id . ':output:' . $this->get_cache_key($key_data);

    }

    return $this->_output_key;

  }

  /**

   * Returns cache key.

   *

   * @param array $key_data

   *   Additional data for cache segmentation and/or overrides for default

   *   segmentation.

   *

   * @return string

   */

  function get_cache_key($key_data = array()) {

    global $user;

    $key_data += array(

      'roles' => array_keys($user->roles),

      'super-user' => $user->uid == 1, // special caching for super user.

      'language' => $GLOBALS['language']->language,

      'base_url' => $GLOBALS['base_url'],

    );

    if (empty($key_data['build_info'])) {

      $build_info = $this->view->build_info;

      foreach (array('query','count_query') as $index) {

        // If the default query back-end is used generate SQL query strings from

        // the query objects.

        if ($build_info[$index] instanceof SelectQueryInterface) {

          $query = clone $build_info[$index];

          $query->preExecute();

          $key_data['build_info'][$index] = array(

            'sql' => (string) $query,

            'arguments' => $query->getArguments(),

          );

        }

      }

    }

    $key = md5(serialize($key_data));

    return $key;

  }

}

/**

 * @}

 */