Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
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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| 21 | class FileCache implements CacheInterface |
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| 22 | { |
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| 23 | /** |
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| 24 | * @var string control characters for keys, reserved by PSR-16 |
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| 25 | */ |
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| 26 | const PSR16_RESERVED = '/\{|\}|\(|\)|\/|\\\\|\@|\:/u'; |
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| 27 | |||
| 28 | /** |
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| 29 | * @var string |
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| 30 | */ |
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| 31 | private $cache_path; |
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| 32 | |||
| 33 | /** |
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| 34 | * @var int |
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| 35 | */ |
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| 36 | private $default_ttl; |
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| 37 | |||
| 38 | /** |
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| 39 | * @var int |
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| 40 | */ |
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| 41 | private $dir_mode; |
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| 42 | |||
| 43 | /** |
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| 44 | * @var int |
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| 45 | */ |
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| 46 | private $file_mode; |
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| 47 | |||
| 48 | /** |
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| 49 | * @param string $cache_path absolute root path of cache-file folder |
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| 50 | * @param int $default_ttl default time-to-live (in seconds) |
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| 51 | * @param int $dir_mode permission mode for created dirs |
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| 52 | * @param int $file_mode permission mode for created files |
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| 53 | */ |
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| 54 | 207 | public function __construct($cache_path, $default_ttl, $dir_mode = 0775, $file_mode = 0664) |
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| 55 | { |
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| 56 | 207 | $this->default_ttl = $default_ttl; |
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| 57 | 207 | $this->dir_mode = $dir_mode; |
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| 58 | 207 | $this->file_mode = $file_mode; |
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| 59 | |||
| 60 | 207 | if (! file_exists($cache_path) && file_exists(dirname($cache_path))) { |
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| 61 | 207 | $this->mkdir($cache_path); // ensure that the parent path exists |
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| 62 | } |
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| 63 | |||
| 64 | 207 | $path = realpath($cache_path); |
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| 65 | |||
| 66 | 207 | if ($path === false) { |
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| 67 | throw new InvalidArgumentException("cache path does not exist: {$cache_path}"); |
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| 68 | } |
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| 69 | |||
| 70 | 207 | if (! is_writable($path . DIRECTORY_SEPARATOR)) { |
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| 71 | throw new InvalidArgumentException("cache path is not writable: {$cache_path}"); |
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| 72 | } |
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| 73 | |||
| 74 | 207 | $this->cache_path = $path; |
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| 75 | 207 | } |
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| 76 | |||
| 77 | 111 | public function get($key, $default = null) |
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| 78 | { |
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| 79 | 111 | $path = $this->getPath($key); |
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| 80 | |||
| 81 | 75 | $expires_at = @filemtime($path); |
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| 82 | |||
| 83 | 75 | if ($expires_at === false) { |
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| 84 | 40 | return $default; // file not found |
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| 85 | } |
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| 86 | |||
| 87 | 50 | if ($this->getTime() >= $expires_at) { |
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| 88 | 8 | @unlink($path); // file expired |
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| 89 | |||
| 90 | 8 | return $default; |
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| 91 | } |
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| 92 | |||
| 93 | 47 | $data = @file_get_contents($path); |
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| 94 | |||
| 95 | 47 | if ($data === false) { |
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| 96 | return $default; // race condition: file not found |
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| 97 | } |
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| 98 | |||
| 99 | 47 | if ($data === 'b:0;') { |
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| 100 | 1 | return false; // because we can't otherwise distinguish a FALSE return-value from unserialize() |
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| 101 | } |
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| 102 | |||
| 103 | 46 | $value = @unserialize($data); |
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| 104 | |||
| 105 | 46 | if ($value === false) { |
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| 106 | return $default; // unserialize() failed |
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| 107 | } |
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| 108 | |||
| 109 | 46 | return $value; |
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| 110 | } |
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| 111 | |||
| 112 | 112 | public function set($key, $value, $ttl = null) |
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| 113 | { |
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| 114 | 112 | $path = $this->getPath($key); |
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| 115 | |||
| 116 | 94 | $dir = dirname($path); |
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| 117 | |||
| 118 | 94 | if (! file_exists($dir)) { |
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| 119 | // ensure that the parent path exists: |
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| 120 | 92 | $this->mkdir($dir); |
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| 121 | } |
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| 122 | |||
| 123 | 94 | $temp_path = $this->cache_path . DIRECTORY_SEPARATOR . uniqid('', true); |
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| 124 | |||
| 125 | 94 | if (is_int($ttl)) { |
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| 126 | 7 | $expires_at = $this->getTime() + $ttl; |
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| 127 | 90 | } elseif ($ttl instanceof DateInterval) { |
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| 128 | 3 | $expires_at = date_create_from_format("U", $this->getTime())->add($ttl)->getTimestamp(); |
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| 129 | 87 | } elseif ($ttl === null) { |
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| 130 | 67 | $expires_at = $this->getTime() + $this->default_ttl; |
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| 131 | } else { |
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| 132 | 20 | throw new InvalidArgumentException("invalid TTL: " . print_r($ttl, true)); |
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| 133 | } |
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| 134 | |||
| 135 | 74 | if (false === @file_put_contents($temp_path, serialize($value))) { |
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| 136 | return false; |
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| 137 | } |
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| 138 | |||
| 139 | 74 | if (false === @chmod($temp_path, $this->file_mode)) { |
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| 140 | return false; |
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| 141 | } |
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| 142 | |||
| 143 | 74 | if (@touch($temp_path, $expires_at) && @rename($temp_path, $path)) { |
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| 144 | 74 | return true; |
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| 145 | } |
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| 146 | |||
| 147 | @unlink($temp_path); |
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| 148 | |||
| 149 | return false; |
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| 150 | } |
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| 151 | |||
| 152 | 42 | public function delete($key) |
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| 153 | { |
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| 154 | 42 | $this->validateKey($key); |
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| 155 | |||
| 156 | 24 | $path = $this->getPath($key); |
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| 157 | |||
| 158 | 24 | return !file_exists($path) || @unlink($path); |
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| 159 | } |
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| 160 | |||
| 161 | 207 | public function clear() |
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| 162 | { |
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| 163 | 207 | $success = true; |
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| 164 | |||
| 165 | 207 | $paths = $this->listPaths(); |
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| 166 | |||
| 167 | 207 | foreach ($paths as $path) { |
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| 168 | 62 | if (! unlink($path)) { |
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| 169 | 62 | $success = false; |
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| 170 | } |
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| 171 | } |
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| 172 | |||
| 173 | 207 | return $success; |
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| 174 | } |
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| 175 | |||
| 176 | 32 | View Code Duplication | public function getMultiple($keys, $default = null) |
| 177 | { |
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| 178 | 32 | if (! is_array($keys) && ! $keys instanceof Traversable) { |
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| 179 | 2 | throw new InvalidArgumentException("keys must be either of type array or Traversable"); |
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| 180 | } |
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| 181 | |||
| 182 | 31 | $values = []; |
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| 183 | |||
| 184 | 31 | foreach ($keys as $key) { |
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| 185 | 31 | $values[$key] = $this->get($key) ?: $default; |
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| 186 | } |
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| 187 | |||
| 188 | 13 | return $values; |
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| 189 | } |
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| 190 | |||
| 191 | 44 | public function setMultiple($values, $ttl = null) |
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| 192 | { |
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| 193 | 44 | if (! is_array($values) && ! $values instanceof Traversable) { |
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| 194 | 2 | throw new InvalidArgumentException("keys must be either of type array or Traversable"); |
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| 195 | } |
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| 196 | |||
| 197 | 43 | $ok = true; |
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| 198 | |||
| 199 | 43 | foreach ($values as $key => $value) { |
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| 200 | 43 | if (is_int($key)) { |
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| 201 | 1 | $key = (string) $key; |
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| 202 | } |
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| 203 | |||
| 204 | 43 | $this->validateKey($key); |
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| 205 | |||
| 206 | 43 | $ok = $this->set($key, $value, $ttl) && $ok; |
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| 207 | } |
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| 208 | |||
| 209 | 16 | return $ok; |
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| 210 | } |
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| 211 | |||
| 212 | 22 | View Code Duplication | public function deleteMultiple($keys) |
| 228 | |||
| 229 | 23 | public function has($key) |
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| 233 | |||
| 234 | 2 | public function increment($key, $step = 1) |
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| 235 | { |
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| 236 | 2 | $path = $this->getPath($key); |
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| 237 | |||
| 238 | 2 | $dir = dirname($path); |
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| 239 | |||
| 240 | 2 | if (! file_exists($dir)) { |
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| 241 | 2 | $this->mkdir($dir); // ensure that the parent path exists |
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| 242 | } |
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| 243 | |||
| 244 | 2 | $lock_path = $dir . DIRECTORY_SEPARATOR . ".lock"; // allows max. 256 client locks at one time |
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| 245 | |||
| 246 | 2 | $lock_handle = fopen($lock_path, "w"); |
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| 247 | |||
| 248 | 2 | flock($lock_handle, LOCK_EX); |
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| 249 | |||
| 250 | 2 | $value = $this->get($key, 0) + $step; |
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| 251 | |||
| 252 | 2 | $ok = $this->set($key, $value); |
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| 253 | |||
| 254 | 2 | flock($lock_handle, LOCK_UN); |
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| 255 | |||
| 256 | 2 | return $ok ? $value : false; |
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| 257 | } |
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| 258 | |||
| 259 | 1 | public function decrement($key, $step = 1) |
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| 263 | |||
| 264 | /** |
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| 265 | * Clean up expired cache-files. |
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| 266 | * |
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| 267 | * This method is outside the scope of the PSR-16 cache concept, and is specific to |
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| 268 | * this implementation, being a file-cache. |
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| 269 | * |
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| 270 | * In scenarios with dynamic keys (such as Session IDs) you should call this method |
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| 271 | * periodically - for example from a scheduled daily cron-job. |
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| 272 | * |
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| 273 | * @return void |
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| 274 | */ |
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| 275 | 1 | public function cleanExpired() |
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| 287 | |||
| 288 | /** |
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| 289 | * For a given cache key, obtain the absolute file path |
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| 290 | * |
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| 291 | * @param string $key |
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| 292 | * |
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| 293 | * @return string absolute path to cache-file |
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| 294 | * |
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| 295 | * @throws InvalidArgumentException if the specified key contains a character reserved by PSR-16 |
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| 296 | */ |
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| 297 | 186 | protected function getPath($key) |
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| 311 | |||
| 312 | /** |
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| 313 | * @return int current timestamp |
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| 314 | */ |
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| 315 | 75 | protected function getTime() |
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| 319 | |||
| 320 | /** |
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| 321 | * @return Generator|string[] |
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| 322 | */ |
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| 323 | 207 | protected function listPaths() |
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| 340 | |||
| 341 | /** |
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| 342 | * @param string $key |
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| 343 | * |
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| 344 | * @throws InvalidArgumentException |
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| 345 | */ |
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| 346 | 204 | protected function validateKey($key) |
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| 366 | |||
| 367 | /** |
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| 368 | * Recursively create directories and apply permission mask |
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| 369 | * |
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| 370 | * @param string $path absolute directory path |
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| 371 | */ |
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| 372 | 207 | private function mkdir($path) |
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| 383 | } |
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| 384 |
If you suppress an error, we recommend checking for the error condition explicitly: