memcache-session.inc in Memcache API and Integration 5

User session handling functions.

File

memcache-session.inc

<?php

/**
 * @file
 * User session handling functions.
 */

/**
 * Implement hook_user() using a required module's namespace since memcache is 
 * not a module and thus can't implement hooks directly.
 */
function filter_user($op, &$edit, &$account, $category = NULL) {
  if ($op == 'update') {

    // Invalidate cached user object.
    cache_clear_all($account->uid, 'users');
  }
}
function sess_open($save_path, $session_name) {
  return TRUE;
}
function sess_close() {
  return TRUE;
}
function sess_read($key) {
  global $user;

  // Write and Close handlers are called after destructing objects since PHP 5.0.5
  // Thus destructors can use sessions but session handler can't use objects.
  // So we are moving session closure before destructing objects.
  register_shutdown_function('session_write_close');

  // Handle the case of first time visitors and clients that don't store cookies (eg. web crawlers).
  if (!isset($_COOKIE[session_name()])) {
    $user = drupal_anonymous_user();
    return '';
  }

  // Otherwise, if the session is still active, we have a record of the client's session in memcache.
  $session = dmemcache_get($key, 'session');
  $user = sess_user_load($session);
  return $user->session;
}
function sess_write($key, $value) {
  global $user;

  // If the client doesn't have a session, and one isn't being created ($value),
  // do nothing.  If session saving has been turned off, do nothing.
  if (empty($_COOKIE[session_name()]) && empty($value) || !session_save_session()) {
    return TRUE;
  }

  // Prepare the information to be saved
  $session = new stdClass();
  $session->sid = $key;
  $session->uid = $user->uid;
  $session->cache = $user->cache;
  $session->hostname = $_SERVER["REMOTE_ADDR"];
  $session->session = $value;
  $session->timestamp = $_SERVER['REQUEST_TIME'];

  // Be sure that we have the latest user object.  If user_save() has been
  // called, we need to refresh the object from the database.
  $user = sess_user_load($session);
  if ($user->uid || $value) {
    dmemcache_set($key, $session, ini_get('session.gc_maxlifetime'), 'session');
    dmemcache_set($user->uid, $user, ini_get('session.gc_maxlifetime'), 'users');
    if ($user->uid && $user->access < $_SERVER['REQUEST_TIME'] - 300) {
      db_query("UPDATE {users} SET access = %d WHERE uid = %d", $_SERVER['REQUEST_TIME'], $user->uid);
    }
  }
  return TRUE;
}
function sess_regenerate() {

  // We code around http://bugs.php.net/bug.php?id=32802 by destroying
  // the session cookie by setting expiration in the past (a negative
  // value).  This issue only arises in PHP versions before 4.4.0,
  // regardless of the Drupal configuration.
  // TODO: remove this when we require at least PHP 4.4.0
  if (isset($_COOKIE[session_name()])) {
    setcookie(session_name(), '', $_SERVER['REQUEST_TIME'] - 42000, '/');
  }

  // Store the current (anonymous) session id.
  $old_session_id = session_id();

  // Generate the new (authenticated) session id.
  session_regenerate_id();
  $key = session_id();

  // Grab the user's information that is cached with the anonymous key
  $info = dmemcache_get($old_session_id, 'session');

  // Update it.
  $info->sid = $key;

  // Store it with the new key.
  dmemcache_set($key, $info, ini_get('session.gc_maxlifetime'), 'session');

  // Clear the old data from the cache.
  dmemcache_delete($old_session_id, 'session');
}

/**
 * Counts how many users have sessions. Can count either anonymous sessions, authenticated sessions, or both.
 * Would be insane slow with memcached as we would need to retrieve at least the stats of all object.
 * Not implemented.
 */
function sess_count($timestamp = 0, $anonymous = true) {
}

/**
 * Called by PHP session handling with the PHP session ID to end a user's session.
 *
 * @param  string $sid
 *   the session id
 */
function sess_destroy_sid($sid) {
  dmemcache_delete($sid, 'session');
}

/**
 * End a specific user's session. Not implemented.
 */
function sess_destroy_uid($uid) {
}
function sess_gc($lifetime) {

  // Automatic with memcached.
  // Be sure to adjust 'php_value session.gc_maxlifetime' to a large enough
  // value. For example, if you want user sessions to stay in your database
  // for three weeks before deleting them, you need to set gc_maxlifetime
  // to '1814400'. At that value, only after a user doesn't log in after
  // three weeks (1814400 seconds) will his/her session be removed.
  return TRUE;
}
function sess_user_load($session) {
  $user = new stdClass();

  // We found the client's session record and they are an authenticated user
  if ($session && $session->uid > 0) {
    $user = dmemcache_get($session->uid, 'users');
    if (!$user->uid && $user->uid != 0) {
      $user = db_fetch_object(db_query("SELECT u.* FROM {users} u WHERE u.uid = %d", $session->uid));
      $user = drupal_unpack($user);
      $user->session = empty($session->session) ? '' : $session->session;

      // Add roles element to $user
      $user->roles = array();
      $user->roles[DRUPAL_AUTHENTICATED_RID] = 'authenticated user';
      $result = db_query("SELECT r.rid, r.name FROM {role} r INNER JOIN {users_roles} ur ON ur.rid = r.rid WHERE ur.uid = %d", $user->uid);
      while ($role = db_fetch_object($result)) {
        $user->roles[$role->rid] = $role->name;
      }
    }
    else {
      if ($user->uid) {
        $user->from_cache = TRUE;
        $user->session = empty($session->session) ? '' : $session->session;
      }
      else {

        // This is a rare case that we have a session cached, but no session user object cached.
        // This usually only happens if you kill memcached and restart it.
        $user = drupal_anonymous_user($session->session);
      }
    }
  }
  else {
    $session = isset($session->session) ? $session->session : '';
    $user = drupal_anonymous_user($session);
  }
  return $user;
}

/**
 * Determine whether to save session data of the current request.
 *
 * This function allows the caller to temporarily disable writing of session 
 * data, should the request end while performing potentially dangerous 
 * operations, such as manipulating the global $user object.
 *
 * @param $status
 *   Disables writing of session data when FALSE, (re-)enables writing when 
 *   TRUE.
 *
 * @return FALSE if writing session data has been disabled. Otherwise, TRUE.
 */
function session_save_session($status = NULL) {
  static $save_session = TRUE;
  if (isset($status)) {
    $save_session = $status;
  }
  return $save_session;
}

Functions

Name	Description
filter_user	Implement hook_user() using a required module's namespace since memcache is not a module and thus can't implement hooks directly.
session_save_session	Determine whether to save session data of the current request.
sess_close
sess_count	Counts how many users have sessions. Can count either anonymous sessions, authenticated sessions, or both. Would be insane slow with memcached as we would need to retrieve at least the stats of all object. Not implemented.
sess_destroy_sid	Called by PHP session handling with the PHP session ID to end a user's session.
sess_destroy_uid	End a specific user's session. Not implemented.
sess_gc
sess_open
sess_read
sess_regenerate
sess_user_load
sess_write