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 |
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| 10 | class Backup_Status { |
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| 11 | |||
| 12 | /** |
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| 13 | * The filename for the backup file we are the tracking status of |
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| 14 | * |
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| 15 | * @var string |
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| 16 | */ |
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| 17 | private $filename = ''; |
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| 18 | |||
| 19 | /** |
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| 20 | * [$lock_handler description] |
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| 21 | * |
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| 22 | * @var LockHandler |
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| 23 | */ |
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| 24 | private $lock_handler = ''; |
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| 25 | |||
| 26 | private $callback; |
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| 27 | |||
| 28 | /** |
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| 29 | * @param string $id The unique id for the backup job |
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| 30 | */ |
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| 31 | public function __construct( $id ) { |
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| 35 | |||
| 36 | /** |
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| 37 | * Start the tracking a backup process. |
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| 38 | * |
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| 39 | * This creates a backup running file and issues a file lock. This prevents duplicate |
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| 40 | * instances of this backup process running concurrently and allows us to detect if |
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| 41 | * the PHP thread running the process is killed as that will clear the lock. |
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| 42 | * |
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| 43 | * @param string $backup_filename The filename for the backup file that we're tracking |
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| 44 | * @param string $status_message The initial status for the backup process |
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| 45 | * |
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| 46 | * @return boolean Whether the backup process was success marked as started |
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| 47 | */ |
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| 48 | public function start( $backup_filename, $status_message ) { |
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| 64 | |||
| 65 | /** |
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| 66 | * Mark a backup process as finished. |
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| 67 | * |
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| 68 | * This removes the file lock and deletes the running file. |
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| 69 | */ |
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| 70 | public function finish() { |
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| 83 | |||
| 84 | /** |
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| 85 | * Check if the backup has been started by checking if the running file |
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| 86 | * exists. |
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| 87 | * |
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| 88 | * @return boolean Whether the backup process has been started |
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| 89 | */ |
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| 90 | public function is_started() { |
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| 93 | |||
| 94 | public function is_running() { |
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| 109 | |||
| 110 | /** |
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| 111 | * If the running file exists but isn't locked then the thread that |
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| 112 | * the backup process is running in must have been killed. |
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| 113 | * |
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| 114 | * You should only be running this command from a separate thread |
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| 115 | * |
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| 116 | * @return boolean Whether the backup process has crashed or not |
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| 117 | */ |
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| 118 | public function has_crashed() { |
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| 121 | |||
| 122 | /** |
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| 123 | * Handle a process that's previouly crashed. |
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| 124 | * |
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| 125 | * Delete the partially created backup if it exists and then run the standard |
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| 126 | * cleanup tasks and set an error message for the user. |
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| 127 | * |
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| 128 | * @return bool Whether the crash was handled or not |
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| 129 | */ |
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| 130 | public function cleanup_after_crash() { |
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| 151 | |||
| 152 | /** |
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| 153 | * Catch fatal errors and react accordingly. |
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| 154 | * |
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| 155 | * Hooked into the shutdown action. If we've shutdown because of a Fatal error |
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| 156 | * then we cleanup and set an error message for the user. |
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| 157 | */ |
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| 158 | public function catch_fatals() { |
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| 180 | |||
| 181 | /** |
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| 182 | * Get the filepath for the backup file we're tracking |
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| 183 | * |
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| 184 | * @return string The path to the backup file |
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| 185 | */ |
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| 186 | public function get_backup_filename() { |
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| 198 | |||
| 199 | /** |
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| 200 | * Get the status of the running backup. |
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| 201 | * |
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| 202 | * @return string |
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| 203 | */ |
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| 204 | public function get_status() { |
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| 219 | |||
| 220 | /** |
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| 221 | * Set the status of the running backup |
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| 222 | * |
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| 223 | * @param string $message |
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| 224 | * |
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| 225 | * @return null |
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| 226 | */ |
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| 227 | public function set_status( $message ) { |
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| 247 | |||
| 248 | /** |
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| 249 | * Get the time that the current running backup was started |
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| 250 | * |
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| 251 | * @return int $timestamp |
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| 252 | */ |
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| 253 | public function get_start_time() { |
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| 268 | |||
| 269 | /** |
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| 270 | * Get the path to the backup running file that stores the running backup status |
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| 271 | * |
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| 272 | * @return string |
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| 273 | */ |
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| 274 | public function get_status_filepath() { |
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| 277 | |||
| 278 | public function set_status_callback( $callback ) { |
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| 281 | } |
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| 282 |
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: