throttle.module
Allows configuration of congestion control auto-throttle mechanism.
File
drupal-6.x/modules/throttle/throttle.moduleView source
- <?php
-
- /**
- * @file
- * Allows configuration of congestion control auto-throttle mechanism.
- */
-
- function throttle_menu() {
- $items['admin/settings/throttle'] = array(
- 'title' => '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 = '<p>'. 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.') .'</p>';
- $output .= '<p>'. 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.') .'</p>';
- $output .= '<p>'. t('For more information, see the online handbook entry for <a href="@throttle">Throttle module</a>.', array('@throttle' => 'http://drupal.org/handbook/modules/throttle/')) .'</p>';
- return $output;
- case 'admin/settings/throttle':
- return '<p>'. 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.') .'</p>';
- }
- }