--- /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 @@
+<?php
+// $Id: throttle.module,v 1.83 2007/12/14 18:08:49 goba Exp $
+
+/**
+ * @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>';
+ }
+}