Complex classes like FileCache often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use FileCache, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 22 | class FileCache implements CacheInterface, CounterInterface |
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| 23 | { |
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| 24 | // TODO garbage collection |
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| 25 | |||
| 26 | /** |
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| 27 | * @var string control characters for keys, reserved by PSR-16 |
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| 28 | */ |
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| 29 | const PSR16_RESERVED = '/\{|\}|\(|\)|\/|\\\\|\@|\:/u'; |
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| 30 | |||
| 31 | /** |
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| 32 | * @var string |
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| 33 | */ |
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| 34 | private $cache_path; |
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| 35 | |||
| 36 | /** |
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| 37 | * @var int |
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| 38 | */ |
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| 39 | private $default_ttl; |
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| 40 | |||
| 41 | /** |
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| 42 | * @param string $cache_path absolute root path of cache-file folder |
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| 43 | * @param int $default_ttl default time-to-live (in seconds) |
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| 44 | * |
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| 45 | * @throws InvalidArgumentException if the specified cache-path does not exist (or is not writable) |
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| 46 | */ |
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| 47 | 13 | public function __construct($cache_path, $default_ttl) |
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| 48 | { |
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| 49 | 13 | if (! file_exists($cache_path) && file_exists(dirname($cache_path))) { |
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| 50 | 13 | @mkdir($cache_path, 0777); // ensure that the parent path exists |
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| 51 | } |
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| 52 | |||
| 53 | 13 | $path = realpath($cache_path); |
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| 54 | |||
| 55 | 13 | if ($path === false) { |
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| 56 | throw new InvalidArgumentException("cache path does not exist: {$cache_path}"); |
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| 57 | } |
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| 58 | |||
| 59 | 13 | if (! is_writable($path . DIRECTORY_SEPARATOR)) { |
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| 60 | throw new InvalidArgumentException("cache path is not writable: {$cache_path}"); |
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| 61 | } |
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| 62 | |||
| 63 | 13 | $this->cache_path = $path; |
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| 64 | 13 | $this->default_ttl = $default_ttl; |
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| 65 | 13 | } |
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| 66 | |||
| 67 | 12 | public function get($key, $default = null) |
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| 68 | { |
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| 69 | 12 | $path = $this->getPath($key); |
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| 70 | |||
| 71 | 12 | $expires_at = @filemtime($path); |
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| 72 | |||
| 73 | 12 | if ($expires_at === false) { |
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| 74 | 11 | return $default; // file not found |
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| 75 | } |
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| 76 | |||
| 77 | 10 | if ($this->getTime() >= $expires_at) { |
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| 78 | 4 | @unlink($path); // file expired |
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| 79 | |||
| 80 | 4 | return $default; |
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| 81 | } |
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| 82 | |||
| 83 | 9 | $data = @file_get_contents($path); |
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| 84 | |||
| 85 | 9 | if ($data === false) { |
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| 86 | return $default; // race condition: file not found |
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| 87 | } |
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| 88 | |||
| 89 | 9 | if ($data === 'b:0;') { |
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| 90 | return false; // because we can't otherwise distinguish a FALSE return-value from unserialize() |
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| 91 | } |
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| 92 | |||
| 93 | 9 | $value = @unserialize($data); |
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| 94 | |||
| 95 | 9 | if ($value === false) { |
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| 96 | return $default; // unserialize() failed |
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| 97 | } |
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| 98 | |||
| 99 | 9 | return $value; |
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| 100 | } |
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| 101 | |||
| 102 | 12 | public function set($key, $value, $ttl = null) |
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| 103 | { |
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| 104 | 12 | $path = $this->getPath($key); |
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| 105 | |||
| 106 | 12 | $dir = dirname($path); |
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| 107 | |||
| 108 | 12 | if (! file_exists($dir)) { |
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| 109 | 10 | @mkdir($dir, 0777, true); // ensure that the parent path exists |
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| 110 | } |
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| 111 | |||
| 112 | 12 | $temp_path = $this->cache_path . DIRECTORY_SEPARATOR . uniqid('', true); |
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| 113 | |||
| 114 | 12 | if (is_int($ttl)) { |
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| 115 | 3 | $expires_at = $this->getTime() + $ttl; |
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| 116 | } elseif ($ttl instanceof DateInterval) { |
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| 117 | 1 | $expires_at = date_create_from_format("U", $this->getTime())->add($ttl)->getTimestamp(); |
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| 118 | 8 | } elseif ($ttl === null) { |
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| 119 | 8 | $expires_at = $this->getTime() + $this->default_ttl; |
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| 120 | } else { |
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| 121 | throw new InvalidArgumentException("invalid TTL: " . print_r($ttl, true)); |
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| 122 | } |
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| 123 | |||
| 124 | 12 | if (false === @file_put_contents($temp_path, serialize($value))) { |
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| 125 | return false; |
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| 126 | } |
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| 127 | |||
| 128 | 12 | if (@touch($temp_path, $expires_at) && @rename($temp_path, $path)) { |
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| 129 | 12 | return true; |
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| 130 | } |
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| 131 | |||
| 132 | @unlink($temp_path); |
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| 133 | |||
| 134 | return false; |
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| 135 | } |
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| 136 | |||
| 137 | 2 | public function delete($key) |
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| 138 | { |
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| 139 | 2 | @unlink($this->getPath($key)); |
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| 140 | 2 | } |
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| 141 | |||
| 142 | 13 | public function clear() |
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| 143 | { |
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| 144 | 13 | $paths = $this->listPaths(); |
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| 145 | |||
| 146 | 13 | foreach ($paths as $path) { |
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| 147 | 8 | @unlink($path); |
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| 148 | } |
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| 149 | 13 | } |
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| 150 | |||
| 151 | 2 | public function getMultiple($keys) |
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| 152 | { |
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| 153 | 2 | $values = []; |
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| 154 | |||
| 155 | 2 | foreach ($keys as $key) { |
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| 156 | 2 | $values[$key] = $this->get($key); |
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| 157 | } |
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| 158 | |||
| 159 | 2 | return $values; |
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| 160 | } |
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| 161 | |||
| 162 | 2 | public function setMultiple($items, $ttl = null) |
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| 163 | { |
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| 164 | 2 | $ok = true; |
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| 165 | |||
| 166 | 2 | foreach ($items as $key => $value) { |
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| 167 | 2 | $ok = $this->set($key, $value, $ttl) && $ok; |
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| 168 | } |
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| 169 | |||
| 170 | 2 | return $ok; |
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| 171 | } |
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| 172 | |||
| 173 | 1 | public function deleteMultiple($keys) |
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| 174 | { |
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| 175 | 1 | foreach ($keys as $key) { |
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| 176 | 1 | $this->delete($key); |
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| 177 | } |
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| 178 | 1 | } |
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| 179 | |||
| 180 | 1 | public function has($key) |
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| 181 | { |
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| 182 | 1 | return $this->get($key, $this) !== $this; |
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| 183 | } |
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| 184 | |||
| 185 | 2 | public function increment($key, $step = 1) |
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| 186 | { |
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| 187 | 2 | $path = $this->getPath($key); |
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| 188 | |||
| 189 | 2 | $dir = dirname($path); |
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| 190 | |||
| 191 | 2 | if (! file_exists($dir)) { |
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| 192 | 2 | @mkdir($dir, 0777, true); // ensure that the parent path exists |
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| 193 | } |
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| 194 | |||
| 195 | 2 | $lock_path = $dir . DIRECTORY_SEPARATOR . ".lock"; // allows max. 256 client locks at one time |
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| 196 | |||
| 197 | 2 | $lock_handle = fopen($lock_path, "w"); |
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| 198 | |||
| 199 | 2 | flock($lock_handle, LOCK_EX); |
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| 200 | |||
| 201 | 2 | $value = $this->get($key, 0) + $step; |
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| 202 | |||
| 203 | 2 | $ok = $this->set($key, $value); |
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| 204 | |||
| 205 | 2 | flock($lock_handle, LOCK_UN); |
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| 206 | |||
| 207 | 2 | return $ok ? $value : false; |
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| 208 | } |
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| 209 | |||
| 210 | 1 | public function decrement($key, $step = 1) |
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| 211 | { |
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| 212 | 1 | return $this->increment($key, -$step); |
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| 213 | } |
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| 214 | |||
| 215 | /** |
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| 216 | * Clean up expired cache-files. |
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| 217 | * |
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| 218 | * This method is outside the scope of the PSR-16 cache concept, and is specific to |
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| 219 | * this implementation, being a file-cache. |
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| 220 | * |
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| 221 | * In scenarios with dynamic keys (such as Session IDs) you should call this method |
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| 222 | * periodically - for example from a scheduled daily cron-job. |
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| 223 | * |
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| 224 | * @return void |
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| 225 | */ |
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| 226 | 1 | public function cleanExpired() |
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| 227 | { |
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| 228 | 1 | $now = $this->getTime(); |
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| 229 | |||
| 230 | 1 | $paths = $this->listPaths(); |
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| 231 | |||
| 232 | 1 | foreach ($paths as $path) { |
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| 233 | 1 | if ($now > filemtime($path)) { |
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| 234 | 1 | @unlink($path); |
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| 235 | } |
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| 236 | } |
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| 237 | 1 | } |
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| 238 | |||
| 239 | /** |
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| 240 | * For a given cache key, obtain the absolute file path |
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| 241 | * |
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| 242 | * @param string $key |
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| 243 | * |
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| 244 | * @return string absolute path to cache-file |
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| 245 | * |
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| 246 | * @throws InvalidArgumentException if the specified key contains a character reserved by PSR-16 |
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| 247 | */ |
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| 248 | 13 | protected function getPath($key) |
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| 249 | { |
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| 250 | 13 | if (preg_match(self::PSR16_RESERVED, $key, $match) === 1) { |
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| 251 | throw new InvalidArgumentException("invalid character in key: {$match[0]}"); |
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| 252 | } |
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| 253 | |||
| 254 | 13 | $hash = hash("sha256", $key); |
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| 255 | |||
| 256 | 13 | return $this->cache_path |
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| 257 | 13 | . DIRECTORY_SEPARATOR |
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| 258 | 13 | . strtoupper($hash[0]) |
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| 259 | 13 | . DIRECTORY_SEPARATOR |
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| 260 | 13 | . strtoupper($hash[1]) |
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| 261 | 13 | . DIRECTORY_SEPARATOR |
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| 262 | 13 | . substr($hash, 2); |
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| 263 | } |
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| 264 | |||
| 265 | /** |
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| 266 | * @return int current timestamp |
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| 267 | */ |
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| 268 | 13 | protected function getTime() |
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| 272 | |||
| 273 | /** |
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| 274 | * @return Generator|string[] |
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| 275 | */ |
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| 276 | 13 | protected function listPaths() |
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| 277 | { |
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| 278 | 13 | $iterator = new RecursiveDirectoryIterator( |
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| 279 | 13 | $this->cache_path, |
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| 280 | 13 | FilesystemIterator::CURRENT_AS_PATHNAME | FilesystemIterator::SKIP_DOTS |
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| 281 | ); |
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| 282 | |||
| 283 | 13 | $iterator = new RecursiveIteratorIterator($iterator); |
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| 284 | |||
| 285 | 13 | foreach ($iterator as $path) { |
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| 293 | } |
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| 294 |
If you suppress an error, we recommend checking for the error condition explicitly: