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:
| 1 | <?php | ||
| 10 | class Backup_Status { | ||
| 11 | |||
| 12 | /** | ||
| 13 | * The filename for the backup file we are the tracking status of | ||
| 14 | * | ||
| 15 | * @var string | ||
| 16 | */ | ||
| 17 | private $filename = ''; | ||
| 18 | |||
| 19 | /** | ||
| 20 | * [$lock_handler description] | ||
| 21 | * | ||
| 22 | * @var LockHandler | ||
| 23 | */ | ||
| 24 | private $lock_handler = ''; | ||
| 25 | |||
| 26 | private $callback; | ||
| 27 | |||
| 28 | /** | ||
| 29 | * @param string $id The unique id for the backup job | ||
| 30 | */ | ||
| 31 | 	public function __construct( $id ) { | ||
| 32 | $this->id = (string) $id; | ||
|  | |||
| 33 | $this->cleanup_after_crash(); | ||
| 34 | } | ||
| 35 | |||
| 36 | /** | ||
| 37 | * Start the tracking a backup process. | ||
| 38 | * | ||
| 39 | * This creates a backup running file and issues a file lock. This prevents duplicate | ||
| 40 | * instances of this backup process running concurrently and allows us to detect if | ||
| 41 | * the PHP thread running the process is killed as that will clear the lock. | ||
| 42 | * | ||
| 43 | * @param string $backup_filename The filename for the backup file that we're tracking | ||
| 44 | * @param string $status_message The initial status for the backup process | ||
| 45 | * | ||
| 46 | * @return boolean Whether the backup process was success marked as started | ||
| 47 | */ | ||
| 48 | 	public function start( $backup_filename, $status_message ) { | ||
| 49 | $this->filename = $backup_filename; | ||
| 50 | |||
| 51 | add_action( 'shutdown', array( $this, 'catch_fatals' ), 10 ); | ||
| 52 | |||
| 53 | $this->lock_handler = new LockHandler( basename( $this->get_status_filepath() ), Path::get_path() ); | ||
| 54 | |||
| 55 | 		if ( ! $this->lock_handler->lock() || $this->get_status() ) { | ||
| 56 | return false; | ||
| 57 | } | ||
| 58 | |||
| 59 | return $this->set_status( $status_message ); | ||
| 60 | } | ||
| 61 | |||
| 62 | /** | ||
| 63 | * Mark a backup process as finished. | ||
| 64 | * | ||
| 65 | * This removes the file lock and deletes the running file. | ||
| 66 | */ | ||
| 67 | 	public function finish() { | ||
| 68 | |||
| 69 | 		if ( isset( $this->lock_handler ) && is_a( $this->lock_handler, 'LockHandler' ) ) { | ||
| 70 | $this->lock_handler->release(); | ||
| 71 | } | ||
| 72 | |||
| 73 | // Delete the backup running file | ||
| 74 | 		if ( file_exists( $this->get_status_filepath() ) ) { | ||
| 75 | return unlink( $this->get_status_filepath() ); | ||
| 76 | } | ||
| 77 | |||
| 78 | return false; | ||
| 79 | } | ||
| 80 | |||
| 81 | /** | ||
| 82 | * Check if the backup has been started by checking if the running file | ||
| 83 | * exists. | ||
| 84 | * | ||
| 85 | * @return boolean Whether the backup process has been started | ||
| 86 | */ | ||
| 87 | 	public function is_started() { | ||
| 88 | return (bool) file_exists( $this->get_status_filepath() ); | ||
| 89 | } | ||
| 90 | |||
| 91 | 	public function is_running() { | ||
| 106 | |||
| 107 | /** | ||
| 108 | * If the running file exists but isn't locked then the thread that | ||
| 109 | * the backup process is running in must have been killed. | ||
| 110 | * | ||
| 111 | * You should only be running this command from a separate thread | ||
| 112 | * | ||
| 113 | * @return boolean Whether the backup process has crashed or not | ||
| 114 | */ | ||
| 115 | 	public function has_crashed() { | ||
| 118 | |||
| 119 | /** | ||
| 120 | * Handle a process that's previouly crashed. | ||
| 121 | * | ||
| 122 | * Delete the partially created backup if it exists and then run the standard | ||
| 123 | * cleanup tasks and set an error message for the user. | ||
| 124 | * | ||
| 125 | * @return bool Whether the crash was handled or not | ||
| 126 | */ | ||
| 127 | 	public function cleanup_after_crash() { | ||
| 145 | |||
| 146 | /** | ||
| 147 | * Catch fatal errors and react accordingly. | ||
| 148 | * | ||
| 149 | * Hooked into the shutdown action. If we've shutdown because of a Fatal error | ||
| 150 | * then we cleanup and set an error message for the user. | ||
| 151 | */ | ||
| 152 | 	public function catch_fatals() { | ||
| 174 | |||
| 175 | /** | ||
| 176 | * Get the filepath for the backup file we're tracking | ||
| 177 | * | ||
| 178 | * @return string The path to the backup file | ||
| 179 | */ | ||
| 180 | 	public function get_backup_filename() { | ||
| 181 | |||
| 182 | 		if ( $this->is_started() ) { | ||
| 183 | $status = json_decode( file_get_contents( $this->get_status_filepath() ) ); | ||
| 184 | |||
| 185 | 			if ( ! empty( $status->filename ) ) { | ||
| 186 | $this->filename = $status->filename; | ||
| 187 | } | ||
| 188 | } | ||
| 189 | |||
| 190 | return $this->filename; | ||
| 191 | } | ||
| 192 | |||
| 193 | /** | ||
| 194 | * Get the status of the running backup. | ||
| 195 | * | ||
| 196 | * @return string | ||
| 197 | */ | ||
| 198 | 	public function get_status() { | ||
| 199 | |||
| 200 | 		if ( ! file_exists( $this->get_status_filepath() ) ) { | ||
| 201 | return false; | ||
| 202 | } | ||
| 203 | |||
| 204 | $status = json_decode( file_get_contents( $this->get_status_filepath() ) ); | ||
| 205 | |||
| 206 | 		if ( ! empty( $status->status ) ) { | ||
| 207 | return $status->status; | ||
| 208 | } | ||
| 209 | |||
| 210 | return false; | ||
| 211 | |||
| 212 | } | ||
| 213 | |||
| 214 | /** | ||
| 215 | * Set the status of the running backup | ||
| 216 | * | ||
| 217 | * @param string $message | ||
| 218 | * | ||
| 219 | * @return null | ||
| 220 | */ | ||
| 221 | 	public function set_status( $message ) { | ||
| 222 | |||
| 223 | 		if ( is_callable( $this->callback ) ) { | ||
| 224 | call_user_func( $this->callback, $message ); | ||
| 225 | } | ||
| 226 | |||
| 227 | // If start hasn't been called yet then we wont' have a backup filename | ||
| 228 | 		if ( ! $this->filename ) { | ||
| 229 | return false; | ||
| 230 | } | ||
| 231 | |||
| 232 | $status = json_encode( (object) array( | ||
| 233 | 'filename' => $this->filename, | ||
| 234 | 'started' => $this->get_start_time(), | ||
| 235 | 'status' => $message, | ||
| 236 | ) ); | ||
| 237 | |||
| 238 | return (bool) file_put_contents( $this->get_status_filepath(), $status ); | ||
| 239 | |||
| 240 | } | ||
| 241 | |||
| 242 | /** | ||
| 243 | * Get the time that the current running backup was started | ||
| 244 | * | ||
| 245 | * @return int $timestamp | ||
| 246 | */ | ||
| 247 | 	public function get_start_time() { | ||
| 248 | |||
| 249 | 		if ( ! file_exists( $this->get_status_filepath() ) ) { | ||
| 250 | return 0; | ||
| 251 | } | ||
| 252 | |||
| 253 | $status = json_decode( file_get_contents( $this->get_status_filepath() ) ); | ||
| 254 | |||
| 255 | 		if ( ! empty( $status->started ) && (int) (string) $status->started === $status->started ) { | ||
| 256 | return $status->started; | ||
| 257 | } | ||
| 258 | |||
| 259 | return time(); | ||
| 260 | |||
| 261 | } | ||
| 262 | |||
| 263 | /** | ||
| 264 | * Get the path to the backup running file that stores the running backup status | ||
| 265 | * | ||
| 266 | * @return string | ||
| 267 | */ | ||
| 268 | 	public function get_status_filepath() { | ||
| 269 | return Path::get_path() . '/.backup-' . $this->id . '-running'; | ||
| 270 | } | ||
| 271 | |||
| 272 | 	public function set_status_callback( $callback ) { | ||
| 275 | } | ||
| 276 | 
In PHP it is possible to write to properties without declaring them. For example, the following is perfectly valid PHP code:
Generally, it is a good practice to explictly declare properties to avoid accidental typos and provide IDE auto-completion: