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1 | <?php |
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2 | /** |
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3 | * Process Library |
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4 | * @author Tao <[email protected]> |
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5 | */ |
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6 | namespace Slince\Process; |
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7 | |||
8 | use Slince\Process\Exception\InvalidArgumentException; |
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9 | use Slince\Process\Exception\RuntimeException; |
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10 | |||
11 | class Process implements ProcessInterface |
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12 | { |
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13 | /** |
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14 | * process status,running |
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15 | * @var string |
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16 | */ |
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17 | const STATUS_RUNNING = 'running'; |
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18 | |||
19 | /** |
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20 | * process status,terminated |
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21 | * @var string |
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22 | */ |
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23 | const STATUS_TERMINATED = 'terminated'; |
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24 | |||
25 | /** |
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26 | * callback |
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27 | * @var callable |
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28 | */ |
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29 | protected $callback; |
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30 | |||
31 | /** |
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32 | * pid |
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33 | * @var int |
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34 | */ |
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35 | protected $pid; |
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36 | |||
37 | /** |
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38 | * Whether the process is running |
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39 | * @var bool |
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40 | */ |
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41 | protected $isRunning = false; |
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42 | |||
43 | /** |
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44 | * signal handler |
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45 | * @var SignalHandler |
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46 | */ |
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47 | protected $signalHandler; |
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48 | |||
49 | /** |
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50 | * current status |
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51 | * @var Status |
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52 | */ |
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53 | protected $status; |
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54 | |||
55 | public function __construct($callback) |
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56 | { |
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57 | if (!static::isSupported()) { |
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58 | throw new RuntimeException("Process need ext-pcntl"); |
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59 | } |
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60 | if (!is_callable($callback)) { |
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61 | throw new InvalidArgumentException("Process expects a callable callback"); |
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62 | } |
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63 | $this->callback = $callback; |
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64 | $this->signalHandler = SignalHandler::create(); |
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65 | } |
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66 | |||
67 | /** |
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68 | * Checks whether the current environment supports this |
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69 | * @return bool |
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70 | */ |
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71 | public static function isSupported() |
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72 | { |
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73 | return function_exists('pcntl_fork'); |
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74 | } |
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75 | |||
76 | /** |
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77 | * {@inheritdoc} |
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78 | */ |
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79 | public function start() |
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80 | { |
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81 | if ($this->isRunning()) { |
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82 | throw new RuntimeException("The process is already running"); |
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83 | } |
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84 | $pid = pcntl_fork(); |
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85 | if ($pid == -1) { |
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86 | throw new RuntimeException("Could not fork"); |
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87 | } elseif ($pid) { //Records the pid of the child process |
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88 | $this->pid = $pid; |
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89 | $this->isRunning = true; |
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90 | } else { |
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91 | $this->pid = posix_getpid(); |
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92 | try { |
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93 | $exitCode = call_user_func($this->callback); |
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94 | } catch (\Exception $e) { |
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95 | $exitCode = 255; |
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96 | } |
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97 | exit(intval($exitCode)); |
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98 | } |
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99 | } |
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100 | |||
101 | /** |
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102 | * {@inheritdoc} |
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103 | */ |
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104 | public function wait() |
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105 | { |
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106 | if ($this->isRunning()) { |
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107 | $this->updateStatus(true); |
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108 | } |
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109 | } |
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110 | |||
111 | /** |
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112 | * Start and wait for the process to complete |
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113 | */ |
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114 | public function run() |
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115 | { |
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116 | $this->start(); |
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117 | $this->wait(); |
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118 | } |
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119 | |||
120 | /** |
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121 | * {@inheritdoc} |
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122 | */ |
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123 | public function stop($signal = SIGKILL) |
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124 | { |
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125 | $this->signal($signal); |
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126 | $this->updateStatus(true); |
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127 | } |
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128 | |||
129 | /** |
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130 | * {@inheritdoc} |
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131 | */ |
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132 | public function getPid() |
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133 | { |
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134 | return $this->pid; |
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135 | } |
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136 | |||
137 | /** |
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138 | * {@inheritdoc} |
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139 | */ |
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140 | public function signal($signal) |
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141 | { |
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142 | if (!$this->isRunning()) { |
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143 | throw new RuntimeException("The process is not currently running"); |
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144 | } |
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145 | posix_kill($this->getPid(), $signal); |
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146 | } |
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147 | |||
148 | /** |
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149 | * {@inheritdoc} |
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150 | */ |
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151 | public function isRunning() |
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152 | { |
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153 | //if process is not running, return false |
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154 | if (!$this->isRunning) { |
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155 | return false; |
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156 | } |
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157 | //if the process is running, update process status again |
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158 | $this->updateStatus(false); |
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159 | return $this->isRunning; |
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160 | } |
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161 | |||
162 | /** |
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163 | * Gets the signal handler |
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164 | * @return SignalHandler |
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165 | */ |
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166 | public function getSignalHandler() |
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167 | { |
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168 | return $this->signalHandler; |
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169 | } |
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170 | |||
171 | /** |
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172 | * Gets the exit code of the process |
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173 | * @return int |
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174 | */ |
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175 | public function getExitCode() |
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176 | { |
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177 | return $this->status ? $this->status->getExitCode() : null; |
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178 | } |
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179 | |||
180 | /** |
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181 | * Updates the status of the process |
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182 | * @param bool $blocking |
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183 | * @throws RuntimeException |
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184 | */ |
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185 | protected function updateStatus($blocking = false) |
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186 | { |
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187 | if (!$this->isRunning) { |
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188 | return; |
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189 | } |
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190 | $options = $blocking ? 0 : WNOHANG | WUNTRACED; |
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191 | $result = pcntl_waitpid($this->getPid(), $status, $options); |
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192 | if ($result == -1) { |
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193 | throw new RuntimeException("Error waits on or returns the status of the process"); |
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194 | } elseif ($result) { |
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195 | //The process is terminated |
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196 | $this->isRunning = false; |
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197 | //checks if the process is exited normally |
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198 | $this->status = new Status($status); |
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199 | } else { |
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200 | $this->isRunning = true; |
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201 | } |
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202 | } |
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203 | |||
204 | /** |
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205 | * Gets the status of the process |
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206 | * @return Status |
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207 | */ |
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208 | public function getStatus() |
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209 | { |
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210 | return $this->status; |
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211 | } |
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212 | } |
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_function
expects aPost
object, and outputs the author of the post. The base classPost
returns a simple string and outputting a simple string will work just fine. However, the child classBlogPost
which is a sub-type ofPost
instead decided to return anobject
, and is therefore violating the SOLID principles. If aBlogPost
were passed tomy_function
, PHP would not complain, but ultimately fail when executing thestrtoupper
call in its body.