Drupal模塊講解-Authcache緩存原理詳解教程

2024-08-30 19:06:43

字體：大中小

來源：轉載

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Authcache模塊和Boost模塊的原理不一樣,Boost模塊是生成靜態頁面,所以緩存的效果最好,速度最快,Authcache模塊是利用Drupal自身的緩存機制,生成頁面緩存,由于進入到了Drupal環節,因此速度沒有Boost緩存快,但是優點就是可以靈活的使用PHP/Drupal相關方法,動態處理數據.

Drupal模塊講解-Authcache緩存原理詳解教程

首先,我們從Drupal的bootstrap講起.

function drupal_bootstrap($phase = NULL, $new_phase = TRUE) {

  // Not drupal_static(), because does not depend on any run-time information.

  static $phases = array(

    DRUPAL_BOOTSTRAP_CONFIGURATION,

    DRUPAL_BOOTSTRAP_PAGE_CACHE,

    DRUPAL_BOOTSTRAP_DATABASE,

    DRUPAL_BOOTSTRAP_VARIABLES,

    DRUPAL_BOOTSTRAP_SESSION,

    DRUPAL_BOOTSTRAP_PAGE_HEADER,

    DRUPAL_BOOTSTRAP_LANGUAGE,

    DRUPAL_BOOTSTRAP_FULL,

  );

….

}

這是Drupal自帶的bootstrap的幾個環節(Drupal7),從CONFIGURATION、一直到 FULL,這樣整個Drupal就啟動了,所有的模塊也加載了.

其中我們發現,有一個環節叫 PAGE_CACHE,我們來把這個階段的處理函數完整的貼出來,以便大家能更好的理解這段代碼.

function _drupal_bootstrap_page_cache() {

  global $user;

  // Allow specifying special cache handlers in settings.php, like

  // using memcached or files for storing cache information.

  require_once DRUPAL_ROOT . '/includes/cache.inc';

  foreach (variable_get('cache_backends', array()) as $include) {

    require_once DRUPAL_ROOT . '/' . $include;

  }  //開源軟件:Vevb.com

  // Check for a cache mode force from settings.php.

  if (variable_get('page_cache_without_database')) {

    $cache_enabled = TRUE;

  }

  else {

    drupal_bootstrap(DRUPAL_BOOTSTRAP_VARIABLES, FALSE);

    $cache_enabled = variable_get('cache');

  }

  drupal_block_denied(ip_address());

  // If there is no session cookie and cache is enabled (or forced), try

  // to serve a cached page.

  if (!isset($_COOKIE[session_name()]) && $cache_enabled) {

    // Make sure there is a user object because its timestamp will be

    // checked, hook_boot might check for anonymous user etc.

    $user = drupal_anonymous_user();

    // Get the page from the cache.

    $cache = drupal_page_get_cache();

    // If there is a cached page, display it.

    if (is_object($cache)) {

      header('X-Drupal-Cache: HIT');

      // Restore the metadata cached with the page.

      $_GET['q'] = $cache->data['path'];

      drupal_set_title($cache->data['title'], PASS_THROUGH);

      date_default_timezone_set(drupal_get_user_timezone());

      // If the skipping of the bootstrap hooks is not enforced, call

      // hook_boot.

      if (variable_get('page_cache_invoke_hooks', TRUE)) {

        bootstrap_invoke_all('boot');

      }

      drupal_serve_page_from_cache($cache);

      // If the skipping of the bootstrap hooks is not enforced, call

      // hook_exit.

      if (variable_get('page_cache_invoke_hooks', TRUE)) {

        bootstrap_invoke_all('exit');

      }

      // We are done.

      exit;

    }

    else {

      header('X-Drupal-Cache: MISS');

    }

  }

}

當我們看到最下面,exit ;(We are done)之處,我們就知道，Drupal已經處理完了請求,后面的環境(Session、數據庫、模塊、FULL)等環節就不用啟動了,因此大大節省了服務器的處理時間和提高了響應時間.

這就是Drupal自帶的緩存處理機制,Drupal自帶的緩存機制缺點也很明顯,就是只對匿名用戶有效.

因此,Authcache模塊就出現了,Authcache就是利用Drupal自帶的緩存機制,實現對登錄用戶的緩存.

繼續看上面的代碼,其中有3行,如下:

foreach (variable_get('cache_backends', array()) as $include) {

require_once DRUPAL_ROOT . '/' . $include;

}

其中,獲取’cache_backends’的時候,加載了一個數組變量,所以在Drupal自身的緩存階段要使用到authcache,那就必須修改這個 cache_backends.

果如其然,如下所示,我們在安裝authcache的時候,就必須設置如下變量.

$conf['cache_backends'][] = 'sites/all/modules/authcache/authcache.cache.inc';

$conf['cache_backends'][] = 'sites/all/modules/authcache/modules/authcache_builtin/authcache_builtin.cache.inc';

這個時候,我們就加載進了authcache.cache.inc和文件了.

繼續…我們打開authcache.cache.inc 其中,就是定義一些函數,繼續查看authcache_builtin.cache.inc文件,看到如下代碼: