129 lines
5.7 KiB
Plaintext
129 lines
5.7 KiB
Plaintext
<?php
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// $Id$
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/**
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* @file
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* Allows configuration of congestion control auto-throttle mechanism.
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*/
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function throttle_menu() {
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$items['admin/settings/throttle'] = array(
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'title' => 'Throttle',
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'description' => 'Control how your site cuts out content during heavy load.',
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'page callback' => 'drupal_get_form',
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'page arguments' => array('throttle_admin_settings'),
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'access arguments' => array('administer site configuration'),
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'file' => 'throttle.admin.inc',
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);
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return $items;
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}
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/**
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* Determine the current load on the site.
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*
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* Call the throttle_status() function from your own modules, themes, blocks,
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* etc. as follows:
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*
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* $throttle = module_invoke('throttle', 'status');
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*
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* to determine the current throttle status. Use module_invoke() so the
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* call will still work if the throttle module is disabled. For example, in
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* your theme you might choose to disable pictures when your site is too busy
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* (reducing bandwidth), or in your modules you might choose to disable
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* some complicated logic when your site is too busy (reducing CPU utilization).
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*
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* @return
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* 0 or 1. 0 means that the throttle is currently disabled. 1 means that
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* the throttle is currently enabled. When the throttle is enabled, CPU
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* and bandwidth intensive functionality should be disabled.
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*/
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function throttle_status() {
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return variable_get('throttle_level', 0);
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}
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/**
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* Implementation of hook_exit().
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*
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* Changes the current throttle level based on page hits.
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*/
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function throttle_exit() {
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// The following logic determines what the current throttle level should
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// be, and can be disabled by the admin. If enabled, the mt_rand() function
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// returns a number between 0 and N, N being specified by the admin. If
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// 0 is returned, the throttle logic is run, adding two additional database
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// queries. Otherwise, the following logic is skipped. This mechanism is
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// referred to in the admin page as the 'probability limiter', roughly
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// limiting throttle related database calls to 1 in N.
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if (!mt_rand(0, variable_get('throttle_probability_limiter', 9))) {
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// Count users with activity in the past n seconds.
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// This value is defined in the user module Who's Online block.
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$time_period = variable_get('user_block_seconds_online', 900);
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// When determining throttle status in your own module or theme, use
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// $throttle = module_invoke('throttle', 'status');
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// as that will still work when throttle.module is disabled.
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// Clearly here the module is enabled so we call throttle_status() directly.
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$throttle = throttle_status();
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if ($max_guests = variable_get('throttle_anonymous', 0)) {
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$guests = sess_count(time() - $time_period, TRUE);
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}
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else {
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$guests = 0;
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}
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if ($max_users = variable_get('throttle_user', 0)) {
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$users = sess_count(time() - $time_period, FALSE);
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}
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else {
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$users = 0;
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}
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// update the throttle status
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$message = '';
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if ($max_users && $users > $max_users) {
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if (!$throttle) {
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variable_set('throttle_level', 1);
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$message = format_plural($users,
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'1 user accessing site; throttle enabled.',
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'@count users accessing site; throttle enabled.');
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}
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}
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elseif ($max_guests && $guests > $max_guests) {
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if (!$throttle) {
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variable_set('throttle_level', 1);
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$message = format_plural($guests,
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'1 guest accessing site; throttle enabled.',
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'@count guests accessing site; throttle enabled.');
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}
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}
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else {
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if ($throttle) {
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variable_set('throttle_level', 0);
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// Note: unorthodox format_plural() usage due to Gettext plural limitations.
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$message = format_plural($users, '1 user', '@count users') .', ';
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$message .= format_plural($guests, '1 guest accessing site; throttle disabled', '@count guests accessing site; throttle disabled');
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}
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}
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if ($message) {
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cache_clear_all();
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watchdog('throttle', 'Throttle: %message', array('%message' => $message));
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}
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}
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}
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/**
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* Implementation of hook_help().
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*/
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function throttle_help($path, $arg) {
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switch ($path) {
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case 'admin/help#throttle':
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$output = '<p>'. t('The throttle module provides a congestion control mechanism that automatically adjusts to a surge in incoming traffic. If your site is referenced by a popular website, or experiences a "Denial of Service" (DoS) attack, your webserver might become overwhelmed. The throttle mechanism is utilized by modules to temporarily disable CPU-intensive functionality, increasing performance. For instance, via the throttle module, modules may choose to disable resource-intensive blocks or the code within the site theme may temporarily disable user pictures in posts.') .'</p>';
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$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>';
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$output .= '<p>'. t('For more information please read the configuration and customization handbook <a href="@throttle">Throttle page</a>.', array('@throttle' => 'http://drupal.org/handbook/modules/throttle/')) .'</p>';
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return $output;
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case 'admin/settings/throttle':
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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>';
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}
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}
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