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