community_tags_authcache.module

<?php
/**
 * Authcache cycle is thus:
 * - Node page containing user-specific community tags form is marked for caching by authcache ($is_page_authcache).
 * - User's tags are removed from the form and added via ajax to cached page.
 * - Method in JS will be called by authcache by matching value from hook_authcache_ajax().
 */

/**
 * Remove the personalised data in the form - i.e. my tags - these will be
 * loaded via authcache ajax.
 */
function community_tags_authcache_form_community_tags_form_alter(&$form, &$form_state) {
  global $user, $is_page_authcache;

  if($is_page_authcache) {
    if(_community_tags_tag_access()) {
      // unset user specific values in the CT form
      unset($form['tags']['#default_value']);
      unset($form['tags_refs']['#value']);

      // add ct-processed class to prevent CT adding behaviour until user's
      // tags are loaded via ajax.
      $form['tags']['#attributes']['class'] .= ' ct-processed';

      drupal_add_js(drupal_get_path('module', 'community_tags_authcache') .'/community_tags_authcache.js', 'module', 'header');
    }

    // maintain user role cache keys for clearing selected node pages from authcache page cache
    _community_tags_authcache_update_role_keys();
  }
}

/**
 * Maintain the set of role combinations. Store in page cache so that it gets
 * reset when the page cache is cleared.
 *
 * This should be called from the code that determines how the updated content
 * is rendered in the authcached node page. e.g. hook_preprocess for a block
 * where $is_page_authcache is set. Or in the more general case could be called
 * by an implementation of hook_authcache_info() or hook_authcache_ajax() but might
 * result in more redundant calls to cache_clear_all().
 */
function _community_tags_authcache_update_role_keys() {
  global $user;

  // get the list of role keys used so far to cache pages where this function has been invoked.
  $cache_entry = cache_get('authcache_role_keys', 'cache_page');
  $keys = !empty($cache_entry->data) ? $cache_entry->data : array();

  // recreate the roles part of the key that is used to cache the current page.
  $key = _authcache_key($user);

  // update the list of roles keys if necessary
  if (!isset($keys[$key])) {
    $keys[$key] = $key;
    cache_set('authcache_role_keys', $keys, 'cache_page', CACHE_TEMPORARY);
  }
}

/**
 * Implements hook_authcache_ajax().
 *
 * Modifies footer JSON for Ajax call. Cached page, add any context needed to get user's tags as part of ajax call.
 * The value set here will be passed to hooks in authcache_custom.php.
 */
function community_tags_authcache_authcache_ajax() {
  global $user, $theme_key;

  $authcache_ajax = array();

  if (_community_tags_tag_access()) {
    $authcache_ajax['community_tags'] = 1;
  }

  return $authcache_ajax;
}

/**
 * The CT form is cached along with the rest of the node page
 * with mytags removed from the form. Users tags are loaded by authcache and cached by the browser.
 * If any tags are added or removed from node, the cached node page is invalidated which
 * in turn causes a fresh ajax request for mytags.
 */
function community_tags_authcache_community_tags_tags_added($node, $user, $terms) {
  // invalidate the authcache page cache for this node
  _community_tags_authcache_invalidate_nodepage_authcache($node);
}

function community_tags_authcache_community_tags_tags_removed($node, $user, $terms) {
  // invalidate the authcache page cache for this node
  _community_tags_authcache_invalidate_nodepage_authcache($node);
}

/**
 * Remove selected node pages that have been cached by authcache.
 */
function _community_tags_authcache_invalidate_nodepage_authcache($node) {
  global $base_root;

  // Invalidate cached node page for all roles
  $cache_entry = cache_get('authcache_role_keys', 'cache_page');

  if(!empty($cache_entry->data)) {
    $url = url('node/'.$node->nid);

    foreach($cache_entry->data as $role_key) {
      $cache_key = $role_key . $base_root . $url;
      cache_clear_all($cache_key, 'cache_page');
    }
  }
}