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 Job 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 Job, and based on these observations, apply Extract Interface, too.
| 1 | <?php | ||
| 31 | abstract class Job implements IJobSpecification { | ||
| 32 | /** @var string */ | ||
| 33 | public $command; | ||
| 34 | |||
| 35 | /** @var array Array of job parameters */ | ||
| 36 | public $params; | ||
| 37 | |||
| 38 | /** @var array Additional queue metadata */ | ||
| 39 | public $metadata = []; | ||
| 40 | |||
| 41 | /** @var Title */ | ||
| 42 | protected $title; | ||
| 43 | |||
| 44 | /** @var bool Expensive jobs may set this to true */ | ||
| 45 | protected $removeDuplicates; | ||
| 46 | |||
| 47 | /** @var string Text for error that occurred last */ | ||
| 48 | protected $error; | ||
| 49 | |||
| 50 | /** @var callable[] */ | ||
| 51 | protected $teardownCallbacks = []; | ||
| 52 | |||
| 53 | /** | ||
| 54 | * Run the job | ||
| 55 | * @return bool Success | ||
| 56 | */ | ||
| 57 | abstract public function run(); | ||
| 58 | |||
| 59 | /** | ||
| 60 | * Create the appropriate object to handle a specific job | ||
| 61 | * | ||
| 62 | * @param string $command Job command | ||
| 63 | * @param Title $title Associated title | ||
| 64 | * @param array $params Job parameters | ||
| 65 | * @throws MWException | ||
| 66 | * @return Job | ||
| 67 | */ | ||
| 68 | 	public static function factory( $command, Title $title, $params = [] ) { | ||
| 82 | |||
| 83 | /** | ||
| 84 | * @param string $command | ||
| 85 | * @param Title $title | ||
| 86 | * @param array|bool $params Can not be === true | ||
| 87 | */ | ||
| 88 | 	public function __construct( $command, $title, $params = false ) { | ||
| 100 | |||
| 101 | /** | ||
| 102 | * Batch-insert a group of jobs into the queue. | ||
| 103 | * This will be wrapped in a transaction with a forced commit. | ||
| 104 | * | ||
| 105 | * This may add duplicate at insert time, but they will be | ||
| 106 | * removed later on, when the first one is popped. | ||
| 107 | * | ||
| 108 | * @param Job[] $jobs Array of Job objects | ||
| 109 | * @return bool | ||
| 110 | * @deprecated since 1.21 | ||
| 111 | */ | ||
| 112 | 	public static function batchInsert( $jobs ) { | ||
| 117 | |||
| 118 | /** | ||
| 119 | * @return string | ||
| 120 | */ | ||
| 121 | 	public function getType() { | ||
| 124 | |||
| 125 | /** | ||
| 126 | * @return Title | ||
| 127 | */ | ||
| 128 | 	public function getTitle() { | ||
| 131 | |||
| 132 | /** | ||
| 133 | * @return array | ||
| 134 | */ | ||
| 135 | 	public function getParams() { | ||
| 138 | |||
| 139 | /** | ||
| 140 | * @return int|null UNIX timestamp to delay running this job until, otherwise null | ||
| 141 | * @since 1.22 | ||
| 142 | */ | ||
| 143 | 	public function getReleaseTimestamp() { | ||
| 148 | |||
| 149 | /** | ||
| 150 | * @return int|null UNIX timestamp of when the job was queued, or null | ||
| 151 | * @since 1.26 | ||
| 152 | */ | ||
| 153 | 	public function getQueuedTimestamp() { | ||
| 158 | |||
| 159 | /** | ||
| 160 | * @return string|null Id of the request that created this job. Follows | ||
| 161 | * jobs recursively, allowing to track the id of the request that started a | ||
| 162 | * job when jobs insert jobs which insert other jobs. | ||
| 163 | * @since 1.27 | ||
| 164 | */ | ||
| 165 | 	public function getRequestId() { | ||
| 170 | |||
| 171 | /** | ||
| 172 | * @return int|null UNIX timestamp of when the job was runnable, or null | ||
| 173 | * @since 1.26 | ||
| 174 | */ | ||
| 175 | 	public function getReadyTimestamp() { | ||
| 178 | |||
| 179 | /** | ||
| 180 | * Whether the queue should reject insertion of this job if a duplicate exists | ||
| 181 | * | ||
| 182 | * This can be used to avoid duplicated effort or combined with delayed jobs to | ||
| 183 | * coalesce updates into larger batches. Claimed jobs are never treated as | ||
| 184 | * duplicates of new jobs, and some queues may allow a few duplicates due to | ||
| 185 | * network partitions and fail-over. Thus, additional locking is needed to | ||
| 186 | * enforce mutual exclusion if this is really needed. | ||
| 187 | * | ||
| 188 | * @return bool | ||
| 189 | */ | ||
| 190 | 	public function ignoreDuplicates() { | ||
| 193 | |||
| 194 | /** | ||
| 195 | * @return bool Whether this job can be retried on failure by job runners | ||
| 196 | * @since 1.21 | ||
| 197 | */ | ||
| 198 | 	public function allowRetries() { | ||
| 201 | |||
| 202 | /** | ||
| 203 | * @return int Number of actually "work items" handled in this job | ||
| 204 | * @see $wgJobBackoffThrottling | ||
| 205 | * @since 1.23 | ||
| 206 | */ | ||
| 207 | 	public function workItemCount() { | ||
| 210 | |||
| 211 | /** | ||
| 212 | * Subclasses may need to override this to make duplication detection work. | ||
| 213 | * The resulting map conveys everything that makes the job unique. This is | ||
| 214 | * only checked if ignoreDuplicates() returns true, meaning that duplicate | ||
| 215 | * jobs are supposed to be ignored. | ||
| 216 | * | ||
| 217 | * @return array Map of key/values | ||
| 218 | * @since 1.21 | ||
| 219 | */ | ||
| 220 | 	public function getDeduplicationInfo() { | ||
| 241 | |||
| 242 | /** | ||
| 243 | * Get "root job" parameters for a task | ||
| 244 | * | ||
| 245 | * This is used to no-op redundant jobs, including child jobs of jobs, | ||
| 246 | * as long as the children inherit the root job parameters. When a job | ||
| 247 | * with root job parameters and "rootJobIsSelf" set is pushed, the | ||
| 248 | * deduplicateRootJob() method is automatically called on it. If the | ||
| 249 | * root job is only virtual and not actually pushed (e.g. the sub-jobs | ||
| 250 | * are inserted directly), then call deduplicateRootJob() directly. | ||
| 251 | * | ||
| 252 | * @see JobQueue::deduplicateRootJob() | ||
| 253 | * | ||
| 254 | * @param string $key A key that identifies the task | ||
| 255 | * @return array Map of: | ||
| 256 | * - rootJobIsSelf : true | ||
| 257 | * - rootJobSignature : hash (e.g. SHA1) that identifies the task | ||
| 258 | * - rootJobTimestamp : TS_MW timestamp of this instance of the task | ||
| 259 | * @since 1.21 | ||
| 260 | */ | ||
| 261 | 	public static function newRootJobParams( $key ) { | ||
| 268 | |||
| 269 | /** | ||
| 270 | * @see JobQueue::deduplicateRootJob() | ||
| 271 | * @return array | ||
| 272 | * @since 1.21 | ||
| 273 | */ | ||
| 274 | View Code Duplication | 	public function getRootJobParams() { | |
| 284 | |||
| 285 | /** | ||
| 286 | * @see JobQueue::deduplicateRootJob() | ||
| 287 | * @return bool | ||
| 288 | * @since 1.22 | ||
| 289 | */ | ||
| 290 | 	public function hasRootJobParams() { | ||
| 294 | |||
| 295 | /** | ||
| 296 | * @see JobQueue::deduplicateRootJob() | ||
| 297 | * @return bool Whether this is job is a root job | ||
| 298 | */ | ||
| 299 | 	public function isRootJob() { | ||
| 302 | |||
| 303 | /** | ||
| 304 | * @param callable $callback | ||
| 305 | * @since 1.27 | ||
| 306 | */ | ||
| 307 | 	protected function addTeardownCallback( $callback ) { | ||
| 310 | |||
| 311 | /** | ||
| 312 | * Do any final cleanup after run(), deferred updates, and all DB commits happen | ||
| 313 | * | ||
| 314 | * @since 1.27 | ||
| 315 | */ | ||
| 316 | 	public function teardown() { | ||
| 321 | |||
| 322 | /** | ||
| 323 | * Insert a single job into the queue. | ||
| 324 | * @return bool True on success | ||
| 325 | * @deprecated since 1.21 | ||
| 326 | */ | ||
| 327 | 	public function insert() { | ||
| 331 | |||
| 332 | /** | ||
| 333 | * @return string | ||
| 334 | */ | ||
| 335 | 	public function toString() { | ||
| 390 | |||
| 391 | 	protected function setLastError( $error ) { | ||
| 394 | |||
| 395 | 	public function getLastError() { | ||
| 398 | } | ||
| 399 | 
This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)or! empty(...)instead.