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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 BagOStuff 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 BagOStuff, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 47 | abstract class BagOStuff implements IExpiringStore, LoggerAwareInterface { |
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| 48 | /** @var array[] Lock tracking */ |
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| 49 | protected $locks = []; |
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| 50 | /** @var integer ERR_* class constant */ |
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| 51 | protected $lastError = self::ERR_NONE; |
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| 52 | /** @var string */ |
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| 53 | protected $keyspace = 'local'; |
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| 54 | /** @var LoggerInterface */ |
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| 55 | protected $logger; |
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| 56 | /** @var callback|null */ |
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| 57 | protected $asyncHandler; |
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| 58 | /** @var integer Seconds */ |
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| 59 | protected $syncTimeout; |
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| 60 | |||
| 61 | /** @var bool */ |
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| 62 | private $debugMode = false; |
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| 63 | /** @var array */ |
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| 64 | private $duplicateKeyLookups = []; |
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| 65 | /** @var bool */ |
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| 66 | private $reportDupes = false; |
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| 67 | /** @var bool */ |
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| 68 | private $dupeTrackScheduled = false; |
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| 69 | |||
| 70 | /** @var callable[] */ |
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| 71 | protected $busyCallbacks = []; |
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| 72 | |||
| 73 | /** @var integer[] Map of (ATTR_* class constant => QOS_* class constant) */ |
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| 74 | protected $attrMap = []; |
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| 75 | |||
| 76 | /** Possible values for getLastError() */ |
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| 77 | const ERR_NONE = 0; // no error |
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| 78 | const ERR_NO_RESPONSE = 1; // no response |
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| 79 | const ERR_UNREACHABLE = 2; // can't connect |
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| 80 | const ERR_UNEXPECTED = 3; // response gave some error |
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| 81 | |||
| 82 | /** Bitfield constants for get()/getMulti() */ |
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| 83 | const READ_LATEST = 1; // use latest data for replicated stores |
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| 84 | const READ_VERIFIED = 2; // promise that caller can tell when keys are stale |
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| 85 | /** Bitfield constants for set()/merge() */ |
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| 86 | const WRITE_SYNC = 1; // synchronously write to all locations for replicated stores |
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| 87 | const WRITE_CACHE_ONLY = 2; // Only change state of the in-memory cache |
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| 88 | |||
| 89 | /** |
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| 90 | * $params include: |
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| 91 | * - logger: Psr\Log\LoggerInterface instance |
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| 92 | * - keyspace: Default keyspace for $this->makeKey() |
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| 93 | * - asyncHandler: Callable to use for scheduling tasks after the web request ends. |
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| 94 | * In CLI mode, it should run the task immediately. |
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| 95 | * - reportDupes: Whether to emit warning log messages for all keys that were |
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| 96 | * requested more than once (requires an asyncHandler). |
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| 97 | * - syncTimeout: How long to wait with WRITE_SYNC in seconds. |
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| 98 | * @param array $params |
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| 99 | */ |
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| 100 | public function __construct( array $params = [] ) { |
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| 121 | |||
| 122 | /** |
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| 123 | * @param LoggerInterface $logger |
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| 124 | * @return null |
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| 125 | */ |
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| 126 | public function setLogger( LoggerInterface $logger ) { |
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| 129 | |||
| 130 | /** |
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| 131 | * @param bool $bool |
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| 132 | */ |
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| 133 | public function setDebug( $bool ) { |
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| 136 | |||
| 137 | /** |
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| 138 | * Get an item with the given key, regenerating and setting it if not found |
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| 139 | * |
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| 140 | * If the callback returns false, then nothing is stored. |
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| 141 | * |
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| 142 | * @param string $key |
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| 143 | * @param int $ttl Time-to-live (seconds) |
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| 144 | * @param callable $callback Callback that derives the new value |
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| 145 | * @param integer $flags Bitfield of BagOStuff::READ_* constants [optional] |
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| 146 | * @return mixed The cached value if found or the result of $callback otherwise |
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| 147 | * @since 1.27 |
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| 148 | */ |
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| 149 | final public function getWithSetCallback( $key, $ttl, $callback, $flags = 0 ) { |
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| 164 | |||
| 165 | /** |
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| 166 | * Get an item with the given key |
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| 167 | * |
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| 168 | * If the key includes a determistic input hash (e.g. the key can only have |
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| 169 | * the correct value) or complete staleness checks are handled by the caller |
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| 170 | * (e.g. nothing relies on the TTL), then the READ_VERIFIED flag should be set. |
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| 171 | * This lets tiered backends know they can safely upgrade a cached value to |
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| 172 | * higher tiers using standard TTLs. |
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| 173 | * |
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| 174 | * @param string $key |
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| 175 | * @param integer $flags Bitfield of BagOStuff::READ_* constants [optional] |
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| 176 | * @param integer $oldFlags [unused] |
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| 177 | * @return mixed Returns false on failure and if the item does not exist |
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| 178 | */ |
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| 179 | public function get( $key, $flags = 0, $oldFlags = null ) { |
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| 187 | |||
| 188 | /** |
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| 189 | * Track the number of times that a given key has been used. |
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| 190 | * @param string $key |
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| 191 | */ |
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| 192 | private function trackDuplicateKeys( $key ) { |
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| 220 | |||
| 221 | /** |
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| 222 | * @param string $key |
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| 223 | * @param integer $flags Bitfield of BagOStuff::READ_* constants [optional] |
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| 224 | * @return mixed Returns false on failure and if the item does not exist |
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| 225 | */ |
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| 226 | abstract protected function doGet( $key, $flags = 0 ); |
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| 227 | |||
| 228 | /** |
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| 229 | * @note: This method is only needed if merge() uses mergeViaCas() |
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| 230 | * |
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| 231 | * @param string $key |
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| 232 | * @param mixed $casToken |
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| 233 | * @param integer $flags Bitfield of BagOStuff::READ_* constants [optional] |
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| 234 | * @return mixed Returns false on failure and if the item does not exist |
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| 235 | * @throws Exception |
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| 236 | */ |
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| 237 | protected function getWithToken( $key, &$casToken, $flags = 0 ) { |
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| 240 | |||
| 241 | /** |
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| 242 | * Set an item |
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| 243 | * |
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| 244 | * @param string $key |
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| 245 | * @param mixed $value |
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| 246 | * @param int $exptime Either an interval in seconds or a unix timestamp for expiry |
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| 247 | * @param int $flags Bitfield of BagOStuff::WRITE_* constants |
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| 248 | * @return bool Success |
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| 249 | */ |
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| 250 | abstract public function set( $key, $value, $exptime = 0, $flags = 0 ); |
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| 251 | |||
| 252 | /** |
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| 253 | * Delete an item |
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| 254 | * |
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| 255 | * @param string $key |
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| 256 | * @return bool True if the item was deleted or not found, false on failure |
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| 257 | */ |
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| 258 | abstract public function delete( $key ); |
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| 259 | |||
| 260 | /** |
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| 261 | * Merge changes into the existing cache value (possibly creating a new one) |
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| 262 | * |
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| 263 | * The callback function returns the new value given the current value |
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| 264 | * (which will be false if not present), and takes the arguments: |
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| 265 | * (this BagOStuff, cache key, current value, TTL). |
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| 266 | * The TTL parameter is reference set to $exptime. It can be overriden in the callback. |
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| 267 | * |
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| 268 | * @param string $key |
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| 269 | * @param callable $callback Callback method to be executed |
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| 270 | * @param int $exptime Either an interval in seconds or a unix timestamp for expiry |
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| 271 | * @param int $attempts The amount of times to attempt a merge in case of failure |
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| 272 | * @param int $flags Bitfield of BagOStuff::WRITE_* constants |
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| 273 | * @return bool Success |
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| 274 | * @throws InvalidArgumentException |
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| 275 | */ |
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| 276 | public function merge( $key, callable $callback, $exptime = 0, $attempts = 10, $flags = 0 ) { |
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| 279 | |||
| 280 | /** |
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| 281 | * @see BagOStuff::merge() |
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| 282 | * |
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| 283 | * @param string $key |
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| 284 | * @param callable $callback Callback method to be executed |
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| 285 | * @param int $exptime Either an interval in seconds or a unix timestamp for expiry |
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| 286 | * @param int $attempts The amount of times to attempt a merge in case of failure |
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| 287 | * @return bool Success |
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| 288 | */ |
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| 289 | protected function mergeViaCas( $key, $callback, $exptime = 0, $attempts = 10 ) { |
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| 322 | |||
| 323 | /** |
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| 324 | * Check and set an item |
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| 325 | * |
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| 326 | * @param mixed $casToken |
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| 327 | * @param string $key |
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| 328 | * @param mixed $value |
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| 329 | * @param int $exptime Either an interval in seconds or a unix timestamp for expiry |
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| 330 | * @return bool Success |
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| 331 | * @throws Exception |
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| 332 | */ |
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| 333 | protected function cas( $casToken, $key, $value, $exptime = 0 ) { |
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| 336 | |||
| 337 | /** |
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| 338 | * @see BagOStuff::merge() |
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| 339 | * |
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| 340 | * @param string $key |
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| 341 | * @param callable $callback Callback method to be executed |
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| 342 | * @param int $exptime Either an interval in seconds or a unix timestamp for expiry |
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| 343 | * @param int $attempts The amount of times to attempt a merge in case of failure |
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| 344 | * @param int $flags Bitfield of BagOStuff::WRITE_* constants |
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| 345 | * @return bool Success |
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| 346 | */ |
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| 347 | protected function mergeViaLock( $key, $callback, $exptime = 0, $attempts = 10, $flags = 0 ) { |
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| 377 | |||
| 378 | /** |
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| 379 | * Reset the TTL on a key if it exists |
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| 380 | * |
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| 381 | * @param string $key |
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| 382 | * @param int $expiry |
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| 383 | * @return bool Success Returns false if there is no key |
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| 384 | * @since 1.28 |
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| 385 | */ |
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| 386 | public function changeTTL( $key, $expiry = 0 ) { |
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| 391 | |||
| 392 | /** |
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| 393 | * Acquire an advisory lock on a key string |
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| 394 | * |
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| 395 | * Note that if reentry is enabled, duplicate calls ignore $expiry |
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| 396 | * |
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| 397 | * @param string $key |
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| 398 | * @param int $timeout Lock wait timeout; 0 for non-blocking [optional] |
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| 399 | * @param int $expiry Lock expiry [optional]; 1 day maximum |
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| 400 | * @param string $rclass Allow reentry if set and the current lock used this value |
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| 401 | * @return bool Success |
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| 402 | */ |
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| 403 | public function lock( $key, $timeout = 6, $expiry = 6, $rclass = '' ) { |
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| 436 | |||
| 437 | /** |
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| 438 | * Release an advisory lock on a key string |
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| 439 | * |
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| 440 | * @param string $key |
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| 441 | * @return bool Success |
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| 442 | */ |
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| 443 | public function unlock( $key ) { |
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| 452 | |||
| 453 | /** |
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| 454 | * Get a lightweight exclusive self-unlocking lock |
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| 455 | * |
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| 456 | * Note that the same lock cannot be acquired twice. |
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| 457 | * |
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| 458 | * This is useful for task de-duplication or to avoid obtrusive |
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| 459 | * (though non-corrupting) DB errors like INSERT key conflicts |
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| 460 | * or deadlocks when using LOCK IN SHARE MODE. |
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| 461 | * |
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| 462 | * @param string $key |
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| 463 | * @param int $timeout Lock wait timeout; 0 for non-blocking [optional] |
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| 464 | * @param int $expiry Lock expiry [optional]; 1 day maximum |
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| 465 | * @param string $rclass Allow reentry if set and the current lock used this value |
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| 466 | * @return ScopedCallback|null Returns null on failure |
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| 467 | * @since 1.26 |
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| 468 | */ |
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| 469 | final public function getScopedLock( $key, $timeout = 6, $expiry = 30, $rclass = '' ) { |
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| 488 | |||
| 489 | /** |
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| 490 | * Delete all objects expiring before a certain date. |
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| 491 | * @param string $date The reference date in MW format |
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| 492 | * @param callable|bool $progressCallback Optional, a function which will be called |
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| 493 | * regularly during long-running operations with the percentage progress |
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| 494 | * as the first parameter. |
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| 495 | * |
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| 496 | * @return bool Success, false if unimplemented |
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| 497 | */ |
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| 498 | public function deleteObjectsExpiringBefore( $date, $progressCallback = false ) { |
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| 502 | |||
| 503 | /** |
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| 504 | * Get an associative array containing the item for each of the keys that have items. |
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| 505 | * @param array $keys List of strings |
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| 506 | * @param integer $flags Bitfield; supports READ_LATEST [optional] |
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| 507 | * @return array |
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| 508 | */ |
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| 509 | public function getMulti( array $keys, $flags = 0 ) { |
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| 519 | |||
| 520 | /** |
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| 521 | * Batch insertion |
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| 522 | * @param array $data $key => $value assoc array |
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| 523 | * @param int $exptime Either an interval in seconds or a unix timestamp for expiry |
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| 524 | * @return bool Success |
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| 525 | * @since 1.24 |
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| 526 | */ |
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| 527 | public function setMulti( array $data, $exptime = 0 ) { |
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| 536 | |||
| 537 | /** |
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| 538 | * @param string $key |
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| 539 | * @param mixed $value |
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| 540 | * @param int $exptime |
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| 541 | * @return bool Success |
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| 542 | */ |
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| 543 | public function add( $key, $value, $exptime = 0 ) { |
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| 549 | |||
| 550 | /** |
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| 551 | * Increase stored value of $key by $value while preserving its TTL |
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| 552 | * @param string $key Key to increase |
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| 553 | * @param int $value Value to add to $key (Default 1) |
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| 554 | * @return int|bool New value or false on failure |
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| 555 | */ |
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| 556 | public function incr( $key, $value = 1 ) { |
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| 571 | |||
| 572 | /** |
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| 573 | * Decrease stored value of $key by $value while preserving its TTL |
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| 574 | * @param string $key |
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| 575 | * @param int $value |
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| 576 | * @return int|bool New value or false on failure |
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| 577 | */ |
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| 578 | public function decr( $key, $value = 1 ) { |
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| 581 | |||
| 582 | /** |
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| 583 | * Increase stored value of $key by $value while preserving its TTL |
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| 584 | * |
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| 585 | * This will create the key with value $init and TTL $ttl instead if not present |
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| 586 | * |
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| 587 | * @param string $key |
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| 588 | * @param int $ttl |
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| 589 | * @param int $value |
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| 590 | * @param int $init |
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| 591 | * @return int|bool New value or false on failure |
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| 592 | * @since 1.24 |
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| 593 | */ |
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| 594 | public function incrWithInit( $key, $ttl, $value = 1, $init = 1 ) { |
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| 607 | |||
| 608 | /** |
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| 609 | * Get the "last error" registered; clearLastError() should be called manually |
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| 610 | * @return int ERR_* constant for the "last error" registry |
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| 611 | * @since 1.23 |
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| 612 | */ |
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| 613 | public function getLastError() { |
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| 616 | |||
| 617 | /** |
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| 618 | * Clear the "last error" registry |
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| 619 | * @since 1.23 |
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| 620 | */ |
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| 621 | public function clearLastError() { |
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| 624 | |||
| 625 | /** |
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| 626 | * Set the "last error" registry |
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| 627 | * @param int $err ERR_* constant |
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| 628 | * @since 1.23 |
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| 629 | */ |
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| 630 | protected function setLastError( $err ) { |
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| 633 | |||
| 634 | /** |
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| 635 | * Let a callback be run to avoid wasting time on special blocking calls |
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| 636 | * |
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| 637 | * The callbacks may or may not be called ever, in any particular order. |
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| 638 | * They are likely to be invoked when something WRITE_SYNC is used used. |
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| 639 | * They should follow a caching pattern as shown below, so that any code |
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| 640 | * using the word will get it's result no matter what happens. |
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| 641 | * @code |
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| 642 | * $result = null; |
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| 643 | * $workCallback = function () use ( &$result ) { |
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| 644 | * if ( !$result ) { |
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| 645 | * $result = .... |
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| 646 | * } |
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| 647 | * return $result; |
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| 648 | * } |
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| 649 | * @endcode |
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| 650 | * |
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| 651 | * @param callable $workCallback |
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| 652 | * @since 1.28 |
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| 653 | */ |
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| 654 | public function addBusyCallback( callable $workCallback ) { |
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| 657 | |||
| 658 | /** |
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| 659 | * Modify a cache update operation array for EventRelayer::notify() |
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| 660 | * |
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| 661 | * This is used for relayed writes, e.g. for broadcasting a change |
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| 662 | * to multiple data-centers. If the array contains a 'val' field |
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| 663 | * then the command involves setting a key to that value. Note that |
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| 664 | * for simplicity, 'val' is always a simple scalar value. This method |
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| 665 | * is used to possibly serialize the value and add any cache-specific |
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| 666 | * key/values needed for the relayer daemon (e.g. memcached flags). |
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| 667 | * |
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| 668 | * @param array $event |
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| 669 | * @return array |
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| 670 | * @since 1.26 |
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| 671 | */ |
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| 672 | public function modifySimpleRelayEvent( array $event ) { |
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| 675 | |||
| 676 | /** |
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| 677 | * @param string $text |
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| 678 | */ |
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| 679 | protected function debug( $text ) { |
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| 686 | |||
| 687 | /** |
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| 688 | * Convert an optionally relative time to an absolute time |
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| 689 | * @param int $exptime |
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| 690 | * @return int |
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| 691 | */ |
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| 692 | protected function convertExpiry( $exptime ) { |
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| 699 | |||
| 700 | /** |
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| 701 | * Convert an optionally absolute expiry time to a relative time. If an |
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| 702 | * absolute time is specified which is in the past, use a short expiry time. |
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| 703 | * |
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| 704 | * @param int $exptime |
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| 705 | * @return int |
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| 706 | */ |
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| 707 | protected function convertToRelative( $exptime ) { |
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| 718 | |||
| 719 | /** |
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| 720 | * Check if a value is an integer |
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| 721 | * |
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| 722 | * @param mixed $value |
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| 723 | * @return bool |
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| 724 | */ |
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| 725 | protected function isInteger( $value ) { |
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| 728 | |||
| 729 | /** |
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| 730 | * Construct a cache key. |
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| 731 | * |
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| 732 | * @since 1.27 |
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| 733 | * @param string $keyspace |
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| 734 | * @param array $args |
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| 735 | * @return string |
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| 736 | */ |
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| 737 | public function makeKeyInternal( $keyspace, $args ) { |
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| 745 | |||
| 746 | /** |
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| 747 | * Make a global cache key. |
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| 748 | * |
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| 749 | * @since 1.27 |
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| 750 | * @param string ... Key component (variadic) |
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| 751 | * @return string |
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| 752 | */ |
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| 753 | public function makeGlobalKey() { |
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| 756 | |||
| 757 | /** |
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| 758 | * Make a cache key, scoped to this instance's keyspace. |
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| 759 | * |
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| 760 | * @since 1.27 |
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| 761 | * @param string ... Key component (variadic) |
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| 762 | * @return string |
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| 763 | */ |
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| 764 | public function makeKey() { |
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| 767 | |||
| 768 | /** |
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| 769 | * @param integer $flag ATTR_* class constant |
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| 770 | * @return integer QOS_* class constant |
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| 771 | * @since 1.28 |
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| 772 | */ |
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| 773 | public function getQoS( $flag ) { |
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| 776 | |||
| 777 | /** |
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| 778 | * Merge the flag maps of one or more BagOStuff objects into a "lowest common denominator" map |
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| 779 | * |
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| 780 | * @param BagOStuff[] $bags |
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| 781 | * @return integer[] Resulting flag map (class ATTR_* constant => class QOS_* constant) |
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| 782 | */ |
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| 783 | protected function mergeFlagMaps( array $bags ) { |
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| 797 | } |
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| 798 |
Let’s assume that you have a directory layout like this:
. |-- OtherDir | |-- Bar.php | `-- Foo.php `-- SomeDir `-- Foo.phpand let’s assume the following content of
Bar.php:If both files
OtherDir/Foo.phpandSomeDir/Foo.phpare loaded in the same runtime, you will see a PHP error such as the following:PHP Fatal error: Cannot use SomeDir\Foo as Foo because the name is already in use in OtherDir/Foo.phpHowever, as
OtherDir/Foo.phpdoes not necessarily have to be loaded and the error is only triggered if it is loaded beforeOtherDir/Bar.php, this problem might go unnoticed for a while. In order to prevent this error from surfacing, you must import the namespace with a different alias: