diff -r fcf75e232c5b -r 0ff3ba646492 web/drupal/modules/throttle/throttle.module --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/web/drupal/modules/throttle/throttle.module Fri Aug 21 16:26:26 2009 +0000 @@ -0,0 +1,128 @@ + 'Throttle', + 'description' => 'Control how your site cuts out content during heavy load.', + 'page callback' => 'drupal_get_form', + 'page arguments' => array('throttle_admin_settings'), + 'access arguments' => array('administer site configuration'), + 'file' => 'throttle.admin.inc', + ); + return $items; +} + +/** + * Determine the current load on the site. + * + * Call the throttle_status() function from your own modules, themes, blocks, + * etc. as follows: + * + * $throttle = module_invoke('throttle', 'status'); + * + * to determine the current throttle status. Use module_invoke() so the + * call will still work if the throttle module is disabled. For example, in + * your theme you might choose to disable pictures when your site is too busy + * (reducing bandwidth), or in your modules you might choose to disable + * some complicated logic when your site is too busy (reducing CPU utilization). + * + * @return + * 0 or 1. 0 means that the throttle is currently disabled. 1 means that + * the throttle is currently enabled. When the throttle is enabled, CPU + * and bandwidth intensive functionality should be disabled. + */ +function throttle_status() { + return variable_get('throttle_level', 0); +} + +/** + * Implementation of hook_exit(). + * + * Changes the current throttle level based on page hits. + */ +function throttle_exit() { + // The following logic determines what the current throttle level should + // be, and can be disabled by the admin. If enabled, the mt_rand() function + // returns a number between 0 and N, N being specified by the admin. If + // 0 is returned, the throttle logic is run, adding two additional database + // queries. Otherwise, the following logic is skipped. This mechanism is + // referred to in the admin page as the 'probability limiter', roughly + // limiting throttle related database calls to 1 in N. + if (!mt_rand(0, variable_get('throttle_probability_limiter', 9))) { + + // Count users with activity in the past n seconds. + // This value is defined in the user module Who's Online block. + $time_period = variable_get('user_block_seconds_online', 900); + + // When determining throttle status in your own module or theme, use + // $throttle = module_invoke('throttle', 'status'); + // as that will still work when throttle.module is disabled. + // Clearly here the module is enabled so we call throttle_status() directly. + $throttle = throttle_status(); + + if ($max_guests = variable_get('throttle_anonymous', 0)) { + $guests = sess_count(time() - $time_period, TRUE); + } + else { + $guests = 0; + } + if ($max_users = variable_get('throttle_user', 0)) { + $users = sess_count(time() - $time_period, FALSE); + } + else { + $users = 0; + } + + // update the throttle status + $message = ''; + if ($max_users && $users > $max_users) { + if (!$throttle) { + variable_set('throttle_level', 1); + $message = format_plural($users, + '1 user accessing site; throttle enabled.', + '@count users accessing site; throttle enabled.'); + } + } + elseif ($max_guests && $guests > $max_guests) { + if (!$throttle) { + variable_set('throttle_level', 1); + $message = format_plural($guests, + '1 guest accessing site; throttle enabled.', + '@count guests accessing site; throttle enabled.'); + } + } + else { + if ($throttle) { + variable_set('throttle_level', 0); + // Note: unorthodox format_plural() usage due to Gettext plural limitations. + $message = format_plural($users, '1 user', '@count users') .', '; + $message .= format_plural($guests, '1 guest accessing site; throttle disabled', '@count guests accessing site; throttle disabled'); + } + } + if ($message) { + cache_clear_all(); + watchdog('throttle', 'Throttle: %message', array('%message' => $message)); + } + } +} + +/** + * Implementation of hook_help(). + */ +function throttle_help($path, $arg) { + switch ($path) { + case 'admin/help#throttle': + $output = '

'. t('The throttle module provides a congestion control mechanism that automatically adjusts to a surge in incoming traffic. If your site is referenced by a popular website, or experiences a "Denial of Service" (DoS) attack, your webserver might become overwhelmed. The throttle mechanism is utilized by modules to temporarily disable CPU-intensive functionality, increasing performance. For instance, via the throttle module, modules may choose to disable resource-intensive blocks or the code within the site theme may temporarily disable user pictures in posts.') .'

'; + $output .= '

'. t('The congestion control throttle can be automatically enabled when the number of anonymous or authenticated users currently visiting the site exceeds a specified threshold.') .'

'; + $output .= '

'. t('For more information, see the online handbook entry for Throttle module.', array('@throttle' => 'http://drupal.org/handbook/modules/throttle/')) .'

'; + return $output; + case 'admin/settings/throttle': + return '

'. t('The throttle module provides a congestion control mechanism that automatically adjusts to a surge in incoming traffic. If your site is referenced by a popular website, or experiences a "Denial of Service" (DoS) attack, your webserver might become overwhelmed. The throttle mechanism is utilized by modules to temporarily disable CPU-intensive functionality, increasing performance.') .'

'; + } +}