| 1 |  |  | <?php | 
            
                                                                                                            
                            
            
                                    
            
            
                | 2 |  |  | /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 3 |  |  |  * Nyx | 
            
                                                                                                            
                            
            
                                    
            
            
                | 4 |  |  |  * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 5 |  |  |  * (The MIT license) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 6 |  |  |  * Copyright (c) 2016 Luke Steadman | 
            
                                                                                                            
                            
            
                                    
            
            
                | 7 |  |  |  * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 8 |  |  |  * Permission is hereby granted, free of charge, to any person obtaining a copy | 
            
                                                                                                            
                            
            
                                    
            
            
                | 9 |  |  |  * of this software and associated * documentation files (the "Software"), to | 
            
                                                                                                            
                            
            
                                    
            
            
                | 10 |  |  |  * deal in the Software without restriction, including without limitation the | 
            
                                                                                                            
                            
            
                                    
            
            
                | 11 |  |  |  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or | 
            
                                                                                                            
                            
            
                                    
            
            
                | 12 |  |  |  * sell copies of the Software, and to permit persons to whom the Software is | 
            
                                                                                                            
                            
            
                                    
            
            
                | 13 |  |  |  * furnished to do so, subject to the following conditions: | 
            
                                                                                                            
                            
            
                                    
            
            
                | 14 |  |  |  * The above copyright notice and this permission notice shall be included in | 
            
                                                                                                            
                            
            
                                    
            
            
                | 15 |  |  |  * all copies or substantial portions of the Software. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 16 |  |  |  * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 17 |  |  |  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | 
            
                                                                                                            
                            
            
                                    
            
            
                | 18 |  |  |  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | 
            
                                                                                                            
                            
            
                                    
            
            
                | 19 |  |  |  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | 
            
                                                                                                            
                            
            
                                    
            
            
                | 20 |  |  |  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | 
            
                                                                                                            
                            
            
                                    
            
            
                | 21 |  |  |  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | 
            
                                                                                                            
                            
            
                                    
            
            
                | 22 |  |  |  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | 
            
                                                                                                            
                            
            
                                    
            
            
                | 23 |  |  |  * IN THE SOFTWARE. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 24 |  |  |  * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 25 |  |  |  * @package Nyx | 
            
                                                                                                            
                            
            
                                    
            
            
                | 26 |  |  |  */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 27 |  |  | namespace Nyx; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 28 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 29 |  |  | class Pool implements PoolInterface, OutputableInterface | 
            
                                                                                                            
                            
            
                                    
            
            
                | 30 |  |  | { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 31 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 32 |  |  |      * Default amount of workers to spawn | 
            
                                                                                                            
                            
            
                                    
            
            
                | 33 |  |  |      * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 34 |  |  |      * @var int | 
            
                                                                                                            
                            
            
                                    
            
            
                | 35 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 36 |  |  |     const DEFAULT_WORKER_COUNT = 1; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 37 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 38 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 39 |  |  |      * Immutable. Number of workers this pool maintain | 
            
                                                                                                            
                            
            
                                    
            
            
                | 40 |  |  |      * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 41 |  |  |      * @var int | 
            
                                                                                                            
                            
            
                                    
            
            
                | 42 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 43 |  |  |     protected $numberOfWorkers; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 44 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 45 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 46 |  |  |      * Pool of worker objects | 
            
                                                                                                            
                            
            
                                    
            
            
                | 47 |  |  |      * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 48 |  |  |      * @var array | 
            
                                                                                                            
                            
            
                                    
            
            
                | 49 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 50 |  |  |     protected $workers = array(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 51 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 52 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 53 |  |  |      * @var WorkerInterface | 
            
                                                                                                            
                            
            
                                    
            
            
                | 54 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 55 |  |  |     protected $workerInstance; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 56 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 57 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 58 |  |  |      * @var OutputInterface | 
            
                                                                                                            
                            
            
                                    
            
            
                | 59 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 60 |  |  |     protected $output; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 61 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 62 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 63 |  |  |      * Timestamp of when the pool first started | 
            
                                                                                                            
                            
            
                                    
            
            
                | 64 |  |  |      * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 65 |  |  |      * @var | 
            
                                                                                                            
                            
            
                                    
            
            
                | 66 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 67 |  |  |     protected $started; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 68 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 69 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 70 |  |  |      * Pool constructor. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 71 |  |  |      * | 
            
                                                                                                            
                            
            
                                    
            
            
                | 72 |  |  |      * @param null $numberOfWorkers | 
            
                                                                                                            
                            
            
                                    
            
            
                | 73 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 74 | 9 |  |     public function __construct($numberOfWorkers = null) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 75 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 76 | 9 |  |         if (is_null($numberOfWorkers)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 77 | 9 |  |             $numberOfWorkers = static::DEFAULT_WORKER_COUNT; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 78 | 9 |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 79 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 80 | 9 |  |         $this->numberOfWorkers = $numberOfWorkers; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 81 | 9 |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 82 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 83 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 84 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 85 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 86 | 8 |  |     public function add(WorkerInterface $worker) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 87 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 88 |  |  |         try { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 89 | 8 |  |             $this->setWorkerInstance($worker); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 90 | 8 |  |         } catch (\Exception $e) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 91 | 6 |  |             $this->getOutput()->write('[x] Unable to set worker instance: ' . $e->getMessage()); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 92 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 93 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 94 | 8 |  |         $cmd1 = $worker->getProcess()->getCommand()->getCmd(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 95 | 8 |  |         $cmd2 = $this->workerInstance->getProcess()->getCommand()->getCmd(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 96 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 97 | 8 |  |         if ($cmd1 === $cmd2) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 98 | 8 |  |             $this->workers[] = $worker; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 99 | 8 |  |         } else { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 100 | 1 |  |             $msg = '$worker must be an instance of WorkerInterface and the same as'; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 101 | 1 |  |             throw new \Exception($msg . get_class($worker)); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 102 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 103 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 104 | 8 |  |         return $this; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 105 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 106 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 107 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 108 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 109 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 110 | 8 |  |     public function setWorkerInstance(WorkerInterface $worker) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 111 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 112 | 8 |  |         if (is_null($this->workerInstance)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 113 | 8 |  |             $this->workerInstance = clone $worker; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 114 | 8 |  |         } else { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 115 | 7 |  |             throw new \Exception('setWorkerInstance already called'); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 116 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 117 | 8 |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 118 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 119 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 120 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 121 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 122 | 1 |  |     public function rebuild() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 123 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 124 |  |  |         // Close | 
            
                                                                                                            
                            
            
                                    
            
            
                | 125 | 1 |  |         $this->killAll(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 126 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 127 |  |  |         // Then spawn new ones | 
            
                                                                                                            
                            
            
                                    
            
            
                | 128 | 1 |  |         for ($i = 0; $i < $this->numberOfWorkers; $i++) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 129 | 1 |  |             $this->spawn(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 130 | 1 |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 131 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 132 | 1 |  |         return true; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 133 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 134 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 135 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 136 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 137 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 138 | 5 |  |     public function spawn() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 139 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 140 |  |  |         // Create a clone worker | 
            
                                                                                                            
                            
            
                                    
            
            
                | 141 | 5 |  |         if ($this->numberOfWorkers > count($this->getWorkers())) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 142 | 5 |  |             $worker = clone $this->workerInstance; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 143 | 5 |  |             $this->add($worker); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 144 | 5 |  |             $worker->start(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 145 | 5 |  |         } else { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 146 | 1 |  |             throw new \Exception('Maximum number of workers allocated for this pool ('.$this->numberOfWorkers.').'); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 147 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 148 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 149 | 5 |  |         return $this; | 
                            
                    |  |  |  | 
                                                                                        
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                | 150 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 151 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 152 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 153 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 154 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 155 | 2 |  |     public function kill($pid = null) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 156 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 157 | 2 |  |         $worker = false; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 158 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 159 | 2 |  |         if (is_null($pid)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 160 | 1 |  |             $worker = reset($this->workers); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 161 | 1 |  |             $pid = key($this->workers); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 162 | 2 |  |         } elseif (array_key_exists($pid, $this->workers)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 163 | 1 |  |             $worker = $this->workers[$pid]; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 164 | 1 |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 165 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 166 | 2 |  |         if ($worker) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 167 | 2 |  |             $worker->getProcess()->close(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 168 | 2 |  |             unset($this->workers[$pid]); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 169 | 2 |  |             $this->getOutput()->write('[x] Worker closed.'); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 170 | 2 |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 171 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 172 | 2 |  |         return $this; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 173 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 174 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 175 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 176 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 177 |  |  |      */ | 
            
                                                                        
                            
            
                                    
            
            
                | 178 | 1 |  |     public function killAll() | 
            
                                                                        
                            
            
                                    
            
            
                | 179 |  |  |     { | 
            
                                                                        
                            
            
                                    
            
            
                | 180 | 1 |  |         foreach ($this->workers as $pid => $worker) { | 
            
                                                                        
                            
            
                                    
            
            
                | 181 | 1 |  |             $this->kill($pid); | 
            
                                                                        
                            
            
                                    
            
            
                | 182 | 1 |  |         } | 
            
                                                                        
                            
            
                                    
            
            
                | 183 | 1 |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 184 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 185 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 186 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 187 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 188 | 3 |  |     public function boot() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 189 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 190 | 3 |  |         if (!$this->started) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 191 |  |  |             // Spawn the amount of workers required, if not already set. | 
            
                                                                                                            
                            
            
                                    
            
            
                | 192 | 3 |  |             while (count($this->workers) < $this->numberOfWorkers) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 193 | 3 |  |                 $this->spawn(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 194 | 3 |  |             } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 195 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 196 | 3 |  |             foreach ($this->workers as $worker) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 197 |  |  |                 // Only start the worker if it isn't running | 
            
                                                                                                            
                            
            
                                    
            
            
                | 198 | 3 |  |                 $worker->start(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 199 | 3 |  |             } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 200 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 201 | 3 |  |             $this->started = true; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 202 | 3 |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 203 | 3 |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 204 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 205 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 206 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 207 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 208 |  |  |     public function ping() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 209 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 210 |  |  |         foreach ($this->getWorkers() as $pid => $worker) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 211 |  |  |             // If the worker has stopped, restart it | 
            
                                                                                                            
                            
            
                                    
            
            
                | 212 |  |  |             if (!$worker->getProcess()->isRunning()) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 213 |  |  |                 $this->getOutput()->write('[x] Worker stopped. Spawning a new one.'); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 214 |  |  |                 $this->kill($pid)->spawn(); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 215 |  |  |             } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 216 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 217 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 218 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 219 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 220 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 221 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 222 | 7 |  |     public function getWorkers() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 223 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 224 | 7 |  |         return (array) $this->workers; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 225 |  |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 226 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 227 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 228 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 229 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 230 | 9 |  |     public function setOutput(OutputInterface $output) | 
            
                                                                                                            
                            
            
                                    
            
            
                | 231 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 232 | 9 |  |         $this->output = $output; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 233 | 9 |  |     } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 234 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 235 |  |  |     /** | 
            
                                                                                                            
                            
            
                                    
            
            
                | 236 |  |  |      * {@inheritdoc} | 
            
                                                                                                            
                            
            
                                    
            
            
                | 237 |  |  |      */ | 
            
                                                                                                            
                            
            
                                    
            
            
                | 238 | 6 |  |     public function getOutput() | 
            
                                                                                                            
                            
            
                                    
            
            
                | 239 |  |  |     { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 240 | 6 |  |         if (is_null($this->output)) { | 
            
                                                                                                            
                            
            
                                    
            
            
                | 241 |  |  |             $this->setOutput(new Console()); | 
            
                                                                                                            
                            
            
                                    
            
            
                | 242 |  |  |         } | 
            
                                                                                                            
                            
            
                                    
            
            
                | 243 |  |  |  | 
            
                                                                                                            
                            
            
                                    
            
            
                | 244 | 6 |  |         return $this->output; | 
            
                                                                                                            
                            
            
                                    
            
            
                | 245 |  |  |     } | 
            
                                                                                                            
                                                                
            
                                    
            
            
                | 246 |  |  | } | 
            
                                                        
            
                                    
            
            
                | 247 |  |  |  | 
            
                        
If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design.
Let’s take a look at an example:
Our function
my_functionexpects aPostobject, and outputs the author of the post. The base classPostreturns a simple string and outputting a simple string will work just fine. However, the child classBlogPostwhich is a sub-type ofPostinstead decided to return anobject, and is therefore violating the SOLID principles. If aBlogPostwere passed tomy_function, PHP would not complain, but ultimately fail when executing thestrtouppercall in its body.