1 | <?php |
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2 | /** |
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3 | * Copyright 2011 Bas de Nooijer. All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions are met: |
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7 | * |
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8 | * 1. Redistributions of source code must retain the above copyright notice, |
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9 | * this list of conditions and the following disclaimer. |
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10 | * |
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11 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
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12 | * this listof conditions and the following disclaimer in the documentation |
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13 | * and/or other materials provided with the distribution. |
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14 | * |
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15 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS IS" |
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16 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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17 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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18 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
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19 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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20 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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21 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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22 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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23 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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24 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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25 | * POSSIBILITY OF SUCH DAMAGE. |
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26 | * |
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27 | * The views and conclusions contained in the software and documentation are |
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28 | * those of the authors and should not be interpreted as representing official |
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29 | * policies, either expressed or implied, of the copyright holder. |
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30 | * |
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31 | * @copyright Copyright 2011 Bas de Nooijer <solarium@raspberry.nl> |
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32 | * @license http://github.com/basdenooijer/solarium/raw/master/COPYING |
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33 | * @link http://www.solarium-project.org/ |
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34 | * |
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35 | * @package Solarium |
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36 | */ |
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37 | |
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38 | /** |
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39 | * Loadbalancer plugin |
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40 | * |
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41 | * Using this plugin you can use software loadbalancing over multiple Solr instances. |
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42 | * You can add any number of servers, each with their own weight. The weight influences |
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43 | * the probability of a server being used for a query. |
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44 | * |
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45 | * By default all queries except updates are loadbalanced. This can be customized by setting blocked querytypes. |
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46 | * Any querytype that may not be loadbalanced will be executed by Solarium with the default adapter settings. |
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47 | * In a master-slave setup the default adapter should be connecting to the master server. |
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48 | * |
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49 | * You can also enable the failover mode. In this case a query will be retried on another server in case of error. |
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50 | * |
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51 | * @package Solarium |
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52 | * @subpackage Plugin |
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53 | */ |
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54 | class Solarium_Plugin_Loadbalancer extends Solarium_Plugin_Abstract |
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55 | { |
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56 | |
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57 | /** |
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58 | * Default options |
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59 | * |
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60 | * @var array |
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61 | */ |
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62 | protected $_options = array( |
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63 | 'failoverenabled' => false, |
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64 | 'failovermaxretries' => 1, |
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65 | ); |
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66 | |
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67 | /** |
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68 | * Registered servers |
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69 | * |
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70 | * @var array |
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71 | */ |
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72 | protected $_servers = array(); |
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73 | |
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74 | /** |
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75 | * Query types that are blocked from loadbalancing |
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76 | * |
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77 | * @var array |
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78 | */ |
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79 | protected $_blockedQueryTypes = array( |
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80 | Solarium_Client::QUERYTYPE_UPDATE => true |
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81 | ); |
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82 | |
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83 | /** |
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84 | * Key of the last used server |
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85 | * |
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86 | * The value can be null if no queries have been executed, or if the last executed query didn't use loadbalancing. |
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87 | * |
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88 | * @var null|string |
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89 | */ |
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90 | protected $_lastServerKey; |
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91 | |
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92 | /** |
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93 | * Server to use for next query (overrules randomizer) |
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94 | * |
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95 | * @var string |
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96 | */ |
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97 | protected $_nextServer; |
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98 | |
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99 | /** |
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100 | * Presets of the client adapter |
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101 | * |
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102 | * These settings are used to restore the adapter to it's original status for queries |
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103 | * that cannot be loadbalanced (for instance update queries that need to go to the master) |
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104 | * |
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105 | * @var array |
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106 | */ |
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107 | protected $_adapterPresets; |
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108 | |
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109 | /** |
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110 | * Pool of servers to use for requests |
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111 | * |
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112 | * @var Solarium_Plugin_Loadbalancer_WeightedRandomChoice |
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113 | */ |
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114 | protected $_randomizer; |
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115 | |
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116 | /** |
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117 | * Query type |
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118 | * |
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119 | * @var string |
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120 | */ |
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121 | protected $_queryType; |
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122 | |
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123 | /** |
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124 | * Used for failover mechanism |
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125 | * |
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126 | * @var array |
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127 | */ |
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128 | protected $_serverExcludes; |
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129 | |
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130 | /** |
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131 | * Initialize options |
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132 | * |
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133 | * Several options need some extra checks or setup work, for these options |
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134 | * the setters are called. |
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135 | * |
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136 | * @return void |
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137 | */ |
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138 | protected function _init() |
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139 | { |
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140 | foreach ($this->_options AS $name => $value) { |
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141 | switch ($name) { |
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142 | case 'server': |
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143 | $this->setServers($value); |
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144 | break; |
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145 | case 'blockedquerytype': |
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146 | $this->setBlockedQueryTypes($value); |
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147 | break; |
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148 | } |
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149 | } |
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150 | } |
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151 | |
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152 | /** |
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153 | * Set failover enabled option |
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154 | * |
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155 | * @param bool $value |
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156 | * @return self Provides fluent interface |
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157 | */ |
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158 | public function setFailoverEnabled($value) |
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159 | { |
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160 | return $this->_setOption('failoverenabled', $value); |
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161 | } |
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162 | |
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163 | /** |
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164 | * Get failoverenabled option |
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165 | * |
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166 | * @return boolean |
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167 | */ |
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168 | public function getFailoverEnabled() |
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169 | { |
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170 | return $this->getOption('failoverenabled'); |
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171 | } |
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172 | |
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173 | /** |
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174 | * Set failover max retries |
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175 | * |
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176 | * @param int $value |
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177 | * @return self Provides fluent interface |
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178 | */ |
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179 | public function setFailoverMaxRetries($value) |
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180 | { |
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181 | return $this->_setOption('failovermaxretries', $value); |
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182 | } |
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183 | |
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184 | /** |
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185 | * Get failovermaxretries option |
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186 | * |
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187 | * @return int |
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188 | */ |
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189 | public function getFailoverMaxRetries() |
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190 | { |
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191 | return $this->getOption('failovermaxretries'); |
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192 | } |
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193 | |
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194 | /** |
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195 | * Add a server to the loadbalacing 'pool' |
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196 | * |
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197 | * @param string $key |
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198 | * @param array $options |
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199 | * @param int $weight Must be a positive number |
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200 | * @return self Provides fluent interface |
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201 | */ |
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202 | public function addServer($key, $options, $weight = 1) |
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203 | { |
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204 | if (array_key_exists($key, $this->_servers)) { |
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205 | throw new Solarium_Exception('A server for the loadbalancer plugin must have a unique key'); |
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206 | } else { |
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207 | $this->_servers[$key] = array( |
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208 | 'options' => $options, |
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209 | 'weight' => $weight, |
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210 | ); |
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211 | } |
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212 | |
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213 | // reset the randomizer as soon as a new server is added |
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214 | $this->_randomizer = null; |
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215 | |
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216 | return $this; |
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217 | } |
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218 | |
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219 | /** |
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220 | * Get servers in the loadbalancing pool |
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221 | * |
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222 | * @return array |
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223 | */ |
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224 | public function getServers() |
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225 | { |
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226 | return $this->_servers; |
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227 | } |
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228 | |
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229 | /** |
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230 | * Get a server entry by key |
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231 | * |
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232 | * @param string $key |
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233 | * @return array |
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234 | */ |
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235 | public function getServer($key) |
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236 | { |
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237 | if (!isset($this->_servers[$key])) { |
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238 | throw new Solarium_Exception('Unknown server key'); |
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239 | } |
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240 | |
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241 | return $this->_servers[$key]; |
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242 | } |
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243 | |
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244 | /** |
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245 | * Set servers, overwriting any existing servers |
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246 | * |
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247 | * @param array $servers Use server key as array key and 'options' and 'weight' as array entries |
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248 | * @return self Provides fluent interface |
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249 | */ |
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250 | public function setServers($servers) |
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251 | { |
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252 | $this->clearServers(); |
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253 | $this->addServers($servers); |
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254 | return $this; |
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255 | } |
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256 | |
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257 | /** |
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258 | * Add multiple servers |
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259 | * |
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260 | * @param array $servers |
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261 | * @return self Provides fluent interface |
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262 | */ |
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263 | public function addServers($servers) |
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264 | { |
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265 | foreach ($servers AS $key => $data) { |
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266 | $this->addServer($key, $data['options'], $data['weight']); |
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267 | } |
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268 | |
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269 | return $this; |
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270 | } |
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271 | |
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272 | /** |
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273 | * Clear all server entries |
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274 | * |
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275 | * @return self Provides fluent interface |
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276 | */ |
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277 | public function clearServers() |
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278 | { |
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279 | $this->_servers = array(); |
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280 | } |
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281 | |
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282 | /** |
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283 | * Remove a server by key |
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284 | * |
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285 | * @param string $key |
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286 | * @return self Provides fluent interface |
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287 | */ |
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288 | public function removeServer($key) |
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289 | { |
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290 | if (isset($this->_servers[$key])) { |
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291 | unset($this->_servers[$key]); |
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292 | } |
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293 | |
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294 | return $this; |
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295 | } |
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296 | |
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297 | /** |
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298 | * Set a forced server (by key) for the next request |
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299 | * |
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300 | * As soon as one query has used the forced server this setting is reset. If you want to remove this setting |
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301 | * pass NULL as the key value. |
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302 | * |
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303 | * If the next query cannot be loadbalanced (for instance based on the querytype) this setting is ignored |
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304 | * but will still be reset. |
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305 | * |
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306 | * @param string|null $key |
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307 | * @return self Provides fluent interface |
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308 | */ |
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309 | public function setForcedServerForNextQuery($key) |
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310 | { |
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311 | if ($key !== null && !array_key_exists($key, $this->_servers)) { |
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312 | throw new Solarium_Exception('Unknown server forced for next query'); |
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313 | } |
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314 | |
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315 | $this->_nextServer = $key; |
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316 | return $this; |
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317 | } |
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318 | |
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319 | /** |
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320 | * Get the ForcedServerForNextQuery value |
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321 | * |
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322 | * @return string|null |
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323 | */ |
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324 | public function getForcedServerForNextQuery() |
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325 | { |
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326 | return $this->_nextServer; |
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327 | } |
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328 | |
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329 | /** |
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330 | * Get an array of blocked querytypes |
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331 | * |
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332 | * @return array |
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333 | */ |
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334 | public function getBlockedQueryTypes() |
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335 | { |
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336 | return array_keys($this->_blockedQueryTypes); |
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337 | } |
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338 | |
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339 | /** |
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340 | * Set querytypes to block from loadbalancing |
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341 | * |
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342 | * Overwrites any existing types |
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343 | * |
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344 | * @param array $types Use an array with the constants defined in Solarium_Client as values |
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345 | * @return self Provides fluent interface |
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346 | */ |
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347 | public function setBlockedQueryTypes($types) |
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348 | { |
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349 | $this->clearBlockedQueryTypes(); |
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350 | $this->addBlockedQueryTypes($types); |
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351 | return $this; |
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352 | } |
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353 | |
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354 | /** |
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355 | * Add a querytype to block from loadbalancing |
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356 | * |
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357 | * @param string $type Use one of the constants defined in Solarium_Client |
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358 | * @return self Provides fluent interface |
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359 | */ |
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360 | public function addBlockedQueryType($type) |
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361 | { |
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362 | if (!array_key_exists($type, $this->_blockedQueryTypes)) { |
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363 | $this->_blockedQueryTypes[$type] = true; |
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364 | } |
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365 | |
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366 | return $this; |
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367 | } |
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368 | |
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369 | /** |
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370 | * Add querytypes to block from loadbalancing |
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371 | * |
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372 | * Appended to any existing types |
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373 | * |
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374 | * @param array $types Use an array with the constants defined in Solarium_Client as values |
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375 | * @return self Provides fluent interface |
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376 | */ |
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377 | public function addBlockedQueryTypes($types) |
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378 | { |
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379 | foreach ($types AS $type) { |
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380 | $this->addBlockedQueryType($type); |
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381 | } |
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382 | } |
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383 | |
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384 | /** |
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385 | * Remove a single querytype from the block list |
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386 | * |
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387 | * @param string $type |
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388 | * @return void |
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389 | */ |
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390 | public function removeBlockedQueryType($type) |
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391 | { |
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392 | if (array_key_exists($type, $this->_blockedQueryTypes)) { |
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393 | unset($this->_blockedQueryTypes[$type]); |
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394 | } |
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395 | } |
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396 | |
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397 | /** |
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398 | * Clear all blocked querytypes |
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399 | * |
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400 | * @return self Provides fluent interface |
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401 | */ |
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402 | public function clearBlockedQueryTypes() |
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403 | { |
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404 | $this->_blockedQueryTypes = array(); |
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405 | } |
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406 | |
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407 | /** |
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408 | * Get the key of the server that was used for the last query |
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409 | * |
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410 | * May return a null value if no query has been executed yet, or the last query could not be loadbalanced. |
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411 | * |
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412 | * @return null|string |
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413 | */ |
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414 | public function getLastServerKey() |
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415 | { |
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416 | return $this->_lastServerKey; |
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417 | } |
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418 | |
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419 | /** |
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420 | * Event hook to capture querytype |
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421 | * |
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422 | * @param Solarium_Query $query |
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423 | * @return void |
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424 | */ |
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425 | public function preCreateRequest($query) |
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426 | { |
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427 | $this->_queryType = $query->getType(); |
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428 | } |
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429 | |
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430 | /** |
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431 | * Event hook to adjust client settings just before query execution |
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432 | * |
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433 | * @param Solarium_Client_Request $request |
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434 | * @return Solarium_Client_Response |
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435 | */ |
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436 | public function preExecuteRequest($request) |
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437 | { |
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438 | $adapter = $this->_client->getAdapter(); |
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439 | |
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440 | // save adapter presets (once) to allow the settings to be restored later |
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441 | if ($this->_adapterPresets == null) { |
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442 | $this->_adapterPresets = array( |
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443 | 'host' => $adapter->getHost(), |
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444 | 'port' => $adapter->getPort(), |
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445 | 'path' => $adapter->getPath(), |
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446 | 'core' => $adapter->getCore(), |
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447 | 'timeout' => $adapter->getTimeout(), |
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448 | ); |
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449 | } |
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450 | |
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451 | // check querytype: is loadbalancing allowed? |
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452 | if (!array_key_exists($this->_queryType, $this->_blockedQueryTypes)) { |
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453 | return $this->_getLoadbalancedResponse($request); |
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454 | } else { |
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455 | $options = $this->_adapterPresets; |
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456 | $this->_lastServerKey = null; |
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457 | |
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458 | // apply new settings to adapter |
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459 | $adapter->setOptions($options); |
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460 | |
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461 | // execute request and return result |
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462 | return $adapter->execute($request); |
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463 | } |
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464 | } |
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465 | |
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466 | /** |
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467 | * Execute a request using the adapter |
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468 | * |
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469 | * @param Solarium_Client_Request $request |
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470 | * @return Solarium_Client_Response $response |
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471 | */ |
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472 | protected function _getLoadbalancedResponse($request) |
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473 | { |
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474 | $this->_serverExcludes = array(); // reset for each query |
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475 | $adapter = $this->_client->getAdapter(); |
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476 | |
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477 | if ($this->getFailoverEnabled() == true) { |
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478 | |
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479 | for ($i=0; $i<=$this->getFailoverMaxRetries(); $i++) { |
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480 | $options = $this->_getRandomServerOptions(); |
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481 | $adapter->setOptions($options); |
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482 | try { |
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483 | return $adapter->execute($request); |
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484 | } catch(Solarium_Client_HttpException $e) { |
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485 | // ignore HTTP errors and try again |
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486 | // but do issue an event for things like logging |
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487 | $e = new Solarium_Exception('Maximum number of loadbalancer retries reached'); |
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488 | $this->_client->triggerEvent('LoadbalancerServerFail', array($options, $e)); |
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489 | } |
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490 | } |
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491 | |
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492 | // if we get here no more retries available, throw exception |
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493 | $e = new Solarium_Exception('Maximum number of loadbalancer retries reached'); |
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494 | throw $e; |
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495 | |
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496 | } else { |
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497 | // no failover retries, just execute and let an exception bubble upwards |
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498 | $options = $this->_getRandomServerOptions(); |
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499 | $adapter->setOptions($options); |
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500 | return $adapter->execute($request); |
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501 | } |
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502 | } |
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503 | |
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504 | /** |
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505 | * Get options array for a randomized server |
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506 | * |
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507 | * @return array |
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508 | */ |
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509 | protected function _getRandomServerOptions() |
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510 | { |
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511 | // determine the server to use |
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512 | if ($this->_nextServer !== null) { |
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513 | $serverKey = $this->_nextServer; |
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514 | // reset forced server directly after use |
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515 | $this->_nextServer = null; |
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516 | } else { |
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517 | $serverKey = $this->_getRandomizer()->getRandom($this->_serverExcludes); |
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518 | } |
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519 | |
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520 | $this->_serverExcludes[] = $serverKey; |
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521 | $this->_lastServerKey = $serverKey; |
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522 | return $this->_servers[$serverKey]['options']; |
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523 | } |
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524 | |
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525 | /** |
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526 | * Get randomizer instance |
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527 | * |
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528 | * @return Solarium_Plugin_Loadbalancer_WeightedRandomChoice |
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529 | */ |
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530 | protected function _getRandomizer() |
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531 | { |
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532 | if ($this->_randomizer === null) { |
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533 | $choices = array(); |
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534 | foreach ($this->_servers AS $key => $settings) { |
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535 | $choices[$key] = $settings['weight']; |
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536 | } |
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537 | $this->_randomizer = new Solarium_Plugin_Loadbalancer_WeightedRandomChoice($choices); |
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538 | } |
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539 | |
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540 | return $this->_randomizer; |
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541 | } |
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542 | |
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543 | } |
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