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comparison modules/throttle/throttle.module @ 1:c1f4ac30525a 6.0

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Drupal 6.0
author Franck Deroche <webmaster@defr.org>
date Tue, 23 Dec 2008 14:28:28 +0100
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0:5a113a1c4740 1:c1f4ac30525a
1 <?php
2 // $Id: throttle.module,v 1.83 2007/12/14 18:08:49 goba Exp $
3
4 /**
5 * @file
6 * Allows configuration of congestion control auto-throttle mechanism.
7 */
8
9 function throttle_menu() {
10 $items['admin/settings/throttle'] = array(
11 'title' => 'Throttle',
12 'description' => 'Control how your site cuts out content during heavy load.',
13 'page callback' => 'drupal_get_form',
14 'page arguments' => array('throttle_admin_settings'),
15 'access arguments' => array('administer site configuration'),
16 'file' => 'throttle.admin.inc',
17 );
18 return $items;
19 }
20
21 /**
22 * Determine the current load on the site.
23 *
24 * Call the throttle_status() function from your own modules, themes, blocks,
25 * etc. as follows:
26 *
27 * $throttle = module_invoke('throttle', 'status');
28 *
29 * to determine the current throttle status. Use module_invoke() so the
30 * call will still work if the throttle module is disabled. For example, in
31 * your theme you might choose to disable pictures when your site is too busy
32 * (reducing bandwidth), or in your modules you might choose to disable
33 * some complicated logic when your site is too busy (reducing CPU utilization).
34 *
35 * @return
36 * 0 or 1. 0 means that the throttle is currently disabled. 1 means that
37 * the throttle is currently enabled. When the throttle is enabled, CPU
38 * and bandwidth intensive functionality should be disabled.
39 */
40 function throttle_status() {
41 return variable_get('throttle_level', 0);
42 }
43
44 /**
45 * Implementation of hook_exit().
46 *
47 * Changes the current throttle level based on page hits.
48 */
49 function throttle_exit() {
50 // The following logic determines what the current throttle level should
51 // be, and can be disabled by the admin. If enabled, the mt_rand() function
52 // returns a number between 0 and N, N being specified by the admin. If
53 // 0 is returned, the throttle logic is run, adding two additional database
54 // queries. Otherwise, the following logic is skipped. This mechanism is
55 // referred to in the admin page as the 'probability limiter', roughly
56 // limiting throttle related database calls to 1 in N.
57 if (!mt_rand(0, variable_get('throttle_probability_limiter', 9))) {
58
59 // Count users with activity in the past n seconds.
60 // This value is defined in the user module Who's Online block.
61 $time_period = variable_get('user_block_seconds_online', 900);
62
63 // When determining throttle status in your own module or theme, use
64 // $throttle = module_invoke('throttle', 'status');
65 // as that will still work when throttle.module is disabled.
66 // Clearly here the module is enabled so we call throttle_status() directly.
67 $throttle = throttle_status();
68
69 if ($max_guests = variable_get('throttle_anonymous', 0)) {
70 $guests = sess_count(time() - $time_period, TRUE);
71 }
72 else {
73 $guests = 0;
74 }
75 if ($max_users = variable_get('throttle_user', 0)) {
76 $users = sess_count(time() - $time_period, FALSE);
77 }
78 else {
79 $users = 0;
80 }
81
82 // update the throttle status
83 $message = '';
84 if ($max_users && $users > $max_users) {
85 if (!$throttle) {
86 variable_set('throttle_level', 1);
87 $message = format_plural($users,
88 '1 user accessing site; throttle enabled.',
89 '@count users accessing site; throttle enabled.');
90 }
91 }
92 elseif ($max_guests && $guests > $max_guests) {
93 if (!$throttle) {
94 variable_set('throttle_level', 1);
95 $message = format_plural($guests,
96 '1 guest accessing site; throttle enabled.',
97 '@count guests accessing site; throttle enabled.');
98 }
99 }
100 else {
101 if ($throttle) {
102 variable_set('throttle_level', 0);
103 // Note: unorthodox format_plural() usage due to Gettext plural limitations.
104 $message = format_plural($users, '1 user', '@count users') .', ';
105 $message .= format_plural($guests, '1 guest accessing site; throttle disabled', '@count guests accessing site; throttle disabled');
106 }
107 }
108 if ($message) {
109 cache_clear_all();
110 watchdog('throttle', 'Throttle: %message', array('%message' => $message));
111 }
112 }
113 }
114
115 /**
116 * Implementation of hook_help().
117 */
118 function throttle_help($path, $arg) {
119 switch ($path) {
120 case 'admin/help#throttle':
121 $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>';
122 $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>';
123 $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>';
124 return $output;
125 case 'admin/settings/throttle':
126 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>';
127 }
128 }