| 1 |
<?php |
| 2 |
|
| 3 |
/** |
| 4 |
* A buffer of items from the queue that can be checked out |
| 5 |
*/ |
| 6 |
class Jetpack_Sync_Queue_Buffer { |
| 7 |
public $id; |
| 8 |
public $items_with_ids; |
| 9 |
|
| 10 |
public function __construct( $id, $items_with_ids ) { |
| 11 |
$this->id = $id; |
| 12 |
$this->items_with_ids = $items_with_ids; |
| 13 |
} |
| 14 |
|
| 15 |
public function get_items() { |
| 16 |
return array_combine( $this->get_item_ids(), $this->get_item_values() ); |
| 17 |
} |
| 18 |
|
| 19 |
public function get_item_values() { |
| 20 |
return Jetpack_Sync_Utils::get_item_values( $this->items_with_ids ); |
| 21 |
} |
| 22 |
|
| 23 |
public function get_item_ids() { |
| 24 |
return Jetpack_Sync_Utils::get_item_ids( $this->items_with_ids ); |
| 25 |
} |
| 26 |
} |
| 27 |
|
| 28 |
/** |
| 29 |
* A persistent queue that can be flushed in increments of N items, |
| 30 |
* and which blocks reads until checked-out buffers are checked in or |
| 31 |
* closed. This uses raw SQL for two reasons: speed, and not triggering |
| 32 |
* tons of added_option callbacks. |
| 33 |
*/ |
| 34 |
class Jetpack_Sync_Queue { |
| 35 |
public $id; |
| 36 |
private $row_iterator; |
| 37 |
|
| 38 |
function __construct( $id ) { |
| 39 |
$this->id = str_replace( '-', '_', $id ); // necessary to ensure we don't have ID collisions in the SQL |
| 40 |
$this->row_iterator = 0; |
| 41 |
$this->random_int = mt_rand( 1, 1000000 ); |
| 42 |
} |
| 43 |
|
| 44 |
function add( $item ) { |
| 45 |
global $wpdb; |
| 46 |
$added = false; |
| 47 |
// this basically tries to add the option until enough time has elapsed that |
| 48 |
// it has a unique (microtime-based) option key |
| 49 |
while ( ! $added ) { |
| 50 |
$rows_added = $wpdb->query( $wpdb->prepare( |
| 51 |
"INSERT INTO $wpdb->options (option_name, option_value, autoload) VALUES (%s, %s,%s)", |
| 52 |
$this->get_next_data_row_option_name(), |
| 53 |
serialize( $item ), |
| 54 |
'no' |
| 55 |
) ); |
| 56 |
$added = ( 0 !== $rows_added ); |
| 57 |
} |
| 58 |
} |
| 59 |
|
| 60 |
// Attempts to insert all the items in a single SQL query. May be subject to query size limits! |
| 61 |
function add_all( $items ) { |
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global $wpdb; |
| 63 |
$base_option_name = $this->get_next_data_row_option_name(); |
| 64 |
|
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$query = "INSERT INTO $wpdb->options (option_name, option_value, autoload) VALUES "; |
| 66 |
|
| 67 |
$rows = array(); |
| 68 |
|
| 69 |
for ( $i = 0; $i < count( $items ); $i += 1 ) { |
| 70 |
$option_name = esc_sql( $base_option_name . '-' . $i ); |
| 71 |
$option_value = esc_sql( serialize( $items[ $i ] ) ); |
| 72 |
$rows[] = "('$option_name', '$option_value', 'no')"; |
| 73 |
} |
| 74 |
|
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$rows_added = $wpdb->query( $query . join( ',', $rows ) ); |
| 76 |
|
| 77 |
if ( count( $items ) === $rows_added ) { |
| 78 |
return new WP_Error( 'row_count_mismatch', "The number of rows inserted didn't match the size of the input array" ); |
| 79 |
} |
| 80 |
} |
| 81 |
|
| 82 |
// Peek at the front-most item on the queue without checking it out |
| 83 |
function peek( $count = 1 ) { |
| 84 |
$items = $this->fetch_items( $count ); |
| 85 |
if ( $items ) { |
| 86 |
return Jetpack_Sync_Utils::get_item_values( $items ); |
| 87 |
} |
| 88 |
|
| 89 |
return array(); |
| 90 |
} |
| 91 |
|
| 92 |
// lag is the difference in time between the age of the oldest item |
| 93 |
// (aka first or frontmost item) and the current time |
| 94 |
function lag( $now = null ) { |
| 95 |
global $wpdb; |
| 96 |
|
| 97 |
$first_item_name = $wpdb->get_var( $wpdb->prepare( |
| 98 |
"SELECT option_name FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT 1", |
| 99 |
"jpsq_{$this->id}-%" |
| 100 |
) ); |
| 101 |
|
| 102 |
if ( ! $first_item_name ) { |
| 103 |
return 0; |
| 104 |
} |
| 105 |
|
| 106 |
if ( null === $now ) { |
| 107 |
$now = microtime( true ); |
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} |
| 109 |
|
| 110 |
// break apart the item name to get the timestamp |
| 111 |
$matches = null; |
| 112 |
if ( preg_match( '/^jpsq_' . $this->id . '-(\d+\.\d+)-/', $first_item_name, $matches ) ) { |
| 113 |
return $now - floatval( $matches[1] ); |
| 114 |
} else { |
| 115 |
return 0; |
| 116 |
} |
| 117 |
} |
| 118 |
|
| 119 |
function reset() { |
| 120 |
global $wpdb; |
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$this->delete_checkout_id(); |
| 122 |
$wpdb->query( $wpdb->prepare( |
| 123 |
"DELETE FROM $wpdb->options WHERE option_name LIKE %s", "jpsq_{$this->id}-%" |
| 124 |
) ); |
| 125 |
} |
| 126 |
|
| 127 |
function size() { |
| 128 |
global $wpdb; |
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|
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return (int) $wpdb->get_var( $wpdb->prepare( |
| 131 |
"SELECT count(*) FROM $wpdb->options WHERE option_name LIKE %s", "jpsq_{$this->id}-%" |
| 132 |
) ); |
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} |
| 134 |
|
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// we use this peculiar implementation because it's much faster than count(*) |
| 136 |
function has_any_items() { |
| 137 |
global $wpdb; |
| 138 |
$value = $wpdb->get_var( $wpdb->prepare( |
| 139 |
"SELECT exists( SELECT option_name FROM $wpdb->options WHERE option_name LIKE %s )", "jpsq_{$this->id}-%" |
| 140 |
) ); |
| 141 |
|
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return ( $value === '1' ); |
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} |
| 144 |
|
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function checkout( $buffer_size ) { |
| 146 |
if ( $this->get_checkout_id() ) { |
| 147 |
return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' ); |
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} |
| 149 |
|
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$buffer_id = uniqid(); |
| 151 |
|
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$result = $this->set_checkout_id( $buffer_id ); |
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|
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if ( ! $result || is_wp_error( $result ) ) { |
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return $result; |
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} |
| 157 |
|
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$items = $this->fetch_items( $buffer_size ); |
| 159 |
|
| 160 |
if ( count( $items ) === 0 ) { |
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return false; |
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} |
| 163 |
|
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$buffer = new Jetpack_Sync_Queue_Buffer( $buffer_id, array_slice( $items, 0, $buffer_size ) ); |
| 165 |
|
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return $buffer; |
| 167 |
} |
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|
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// this checks out rows until it either empties the queue or hits a certain memory limit |
| 170 |
// it loads the sizes from the DB first so that it doesn't accidentally |
| 171 |
// load more data into memory than it needs to. |
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// The only way it will load more items than $max_size is if a single queue item |
| 173 |
// exceeds the memory limit, but in that case it will send that item by itself. |
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function checkout_with_memory_limit( $max_memory, $max_buffer_size = 500 ) { |
| 175 |
if ( $this->get_checkout_id() ) { |
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return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' ); |
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} |
| 178 |
|
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$buffer_id = uniqid(); |
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|
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$result = $this->set_checkout_id( $buffer_id ); |
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|
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if ( ! $result || is_wp_error( $result ) ) { |
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return $result; |
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} |
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|
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// get the map of buffer_id -> memory_size |
| 188 |
global $wpdb; |
| 189 |
|
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$items_with_size = $wpdb->get_results( |
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$wpdb->prepare( |
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"SELECT option_name AS id, LENGTH(option_value) AS value_size FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT %d", |
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"jpsq_{$this->id}-%", |
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$max_buffer_size |
| 195 |
), |
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OBJECT |
| 197 |
); |
| 198 |
|
| 199 |
if ( count( $items_with_size ) === 0 ) { |
| 200 |
return false; |
| 201 |
} |
| 202 |
|
| 203 |
$total_memory = 0; |
| 204 |
|
| 205 |
$min_item_id = $max_item_id = $items_with_size[0]->id; |
| 206 |
|
| 207 |
foreach ( $items_with_size as $id => $item_with_size ) { |
| 208 |
$total_memory += $item_with_size->value_size; |
| 209 |
|
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// if this is the first item and it exceeds memory, allow loop to continue |
| 211 |
// we will exit on the next iteration instead |
| 212 |
if ( $total_memory > $max_memory && $id > 0 ) { |
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break; |
| 214 |
} |
| 215 |
|
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$max_item_id = $item_with_size->id; |
| 217 |
} |
| 218 |
|
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$query = $wpdb->prepare( |
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"SELECT option_name AS id, option_value AS value FROM $wpdb->options WHERE option_name >= %s and option_name <= %s ORDER BY option_name ASC", |
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$min_item_id, |
| 222 |
$max_item_id |
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); |
| 224 |
|
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$items = $wpdb->get_results( $query, OBJECT ); |
| 226 |
foreach ( $items as $item ) { |
| 227 |
$item->value = maybe_unserialize( $item->value ); |
| 228 |
} |
| 229 |
|
| 230 |
if ( count( $items ) === 0 ) { |
| 231 |
$this->delete_checkout_id(); |
| 232 |
|
| 233 |
return false; |
| 234 |
} |
| 235 |
|
| 236 |
$buffer = new Jetpack_Sync_Queue_Buffer( $buffer_id, $items ); |
| 237 |
|
| 238 |
return $buffer; |
| 239 |
} |
| 240 |
|
| 241 |
function checkin( $buffer ) { |
| 242 |
$is_valid = $this->validate_checkout( $buffer ); |
| 243 |
|
| 244 |
if ( is_wp_error( $is_valid ) ) { |
| 245 |
return $is_valid; |
| 246 |
} |
| 247 |
|
| 248 |
$this->delete_checkout_id(); |
| 249 |
|
| 250 |
return true; |
| 251 |
} |
| 252 |
|
| 253 |
function close( $buffer, $ids_to_remove = null ) { |
| 254 |
$is_valid = $this->validate_checkout( $buffer ); |
| 255 |
|
| 256 |
if ( is_wp_error( $is_valid ) ) { |
| 257 |
return $is_valid; |
| 258 |
} |
| 259 |
|
| 260 |
$this->delete_checkout_id(); |
| 261 |
|
| 262 |
// by default clear all items in the buffer |
| 263 |
if ( is_null( $ids_to_remove ) ) { |
| 264 |
$ids_to_remove = $buffer->get_item_ids(); |
| 265 |
} |
| 266 |
|
| 267 |
global $wpdb; |
| 268 |
|
| 269 |
if ( count( $ids_to_remove ) > 0 ) { |
| 270 |
$sql = "DELETE FROM $wpdb->options WHERE option_name IN (" . implode( ', ', array_fill( 0, count( $ids_to_remove ), '%s' ) ) . ')'; |
| 271 |
$query = call_user_func_array( array( $wpdb, 'prepare' ), array_merge( array( $sql ), $ids_to_remove ) ); |
| 272 |
$wpdb->query( $query ); |
| 273 |
} |
| 274 |
|
| 275 |
return true; |
| 276 |
} |
| 277 |
|
| 278 |
function flush_all() { |
| 279 |
$items = Jetpack_Sync_Utils::get_item_values( $this->fetch_items() ); |
| 280 |
$this->reset(); |
| 281 |
|
| 282 |
return $items; |
| 283 |
} |
| 284 |
|
| 285 |
function get_all() { |
| 286 |
return $this->fetch_items(); |
| 287 |
} |
| 288 |
|
| 289 |
// use with caution, this could allow multiple processes to delete |
| 290 |
// and send from the queue at the same time |
| 291 |
function force_checkin() { |
| 292 |
$this->delete_checkout_id(); |
| 293 |
} |
| 294 |
|
| 295 |
// used to lock checkouts from the queue. |
| 296 |
// tries to wait up to $timeout seconds for the queue to be empty |
| 297 |
function lock( $timeout = 30 ) { |
| 298 |
$tries = 0; |
| 299 |
|
| 300 |
while ( $this->has_any_items() && $tries < $timeout ) { |
| 301 |
sleep( 1 ); |
| 302 |
$tries += 1; |
| 303 |
} |
| 304 |
|
| 305 |
if ( $tries === 30 ) { |
| 306 |
return new WP_Error( 'lock_timeout', 'Timeout waiting for sync queue to empty' ); |
| 307 |
} |
| 308 |
|
| 309 |
if ( $this->get_checkout_id() ) { |
| 310 |
return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' ); |
| 311 |
} |
| 312 |
|
| 313 |
// hopefully this means we can acquire a checkout? |
| 314 |
$result = $this->set_checkout_id( 'lock' ); |
| 315 |
|
| 316 |
if ( ! $result || is_wp_error( $result ) ) { |
| 317 |
return $result; |
| 318 |
} |
| 319 |
|
| 320 |
return true; |
| 321 |
} |
| 322 |
|
| 323 |
function unlock() { |
| 324 |
return $this->delete_checkout_id(); |
| 325 |
} |
| 326 |
|
| 327 |
/** |
| 328 |
* This option is specifically chosen to, as much as possible, preserve time order |
| 329 |
* and minimise the possibility of collisions between multiple processes working |
| 330 |
* at the same time. |
| 331 |
* |
| 332 |
* @return string |
| 333 |
*/ |
| 334 |
protected function generate_option_name_timestamp() { |
| 335 |
return sprintf( '%.6f', microtime( true ) ); |
| 336 |
} |
| 337 |
|
| 338 |
private function get_checkout_id() { |
| 339 |
global $wpdb; |
| 340 |
$checkout_value = $wpdb->get_var( |
| 341 |
$wpdb->prepare( |
| 342 |
"SELECT option_value FROM $wpdb->options WHERE option_name = %s", |
| 343 |
$this->get_lock_option_name() |
| 344 |
) |
| 345 |
); |
| 346 |
|
| 347 |
if ( $checkout_value ) { |
| 348 |
list( $checkout_id, $timestamp ) = explode( ':', $checkout_value ); |
| 349 |
if ( intval( $timestamp ) > time() ) { |
| 350 |
return $checkout_id; |
| 351 |
} |
| 352 |
} |
| 353 |
|
| 354 |
return false; |
| 355 |
} |
| 356 |
|
| 357 |
private function set_checkout_id( $checkout_id ) { |
| 358 |
global $wpdb; |
| 359 |
|
| 360 |
$expires = time() + Jetpack_Sync_Defaults::$default_sync_queue_lock_timeout; |
| 361 |
$updated_num = $wpdb->query( |
| 362 |
$wpdb->prepare( |
| 363 |
"UPDATE $wpdb->options SET option_value = %s WHERE option_name = %s", |
| 364 |
"$checkout_id:$expires", |
| 365 |
$this->get_lock_option_name() |
| 366 |
) |
| 367 |
); |
| 368 |
|
| 369 |
if ( ! $updated_num ) { |
| 370 |
$updated_num = $wpdb->query( |
| 371 |
$wpdb->prepare( |
| 372 |
"INSERT INTO $wpdb->options ( option_name, option_value, autoload ) VALUES ( %s, %s, 'no' )", |
| 373 |
$this->get_lock_option_name(), |
| 374 |
"$checkout_id:$expires" |
| 375 |
) |
| 376 |
); |
| 377 |
} |
| 378 |
|
| 379 |
return $updated_num; |
| 380 |
} |
| 381 |
|
| 382 |
private function delete_checkout_id() { |
| 383 |
global $wpdb; |
| 384 |
// rather than delete, which causes fragmentation, we update in place |
| 385 |
return $wpdb->query( |
| 386 |
$wpdb->prepare( |
| 387 |
"UPDATE $wpdb->options SET option_value = %s WHERE option_name = %s", |
| 388 |
"0:0", |
| 389 |
$this->get_lock_option_name() |
| 390 |
) |
| 391 |
); |
| 392 |
|
| 393 |
} |
| 394 |
|
| 395 |
private function get_lock_option_name() { |
| 396 |
return "jpsq_{$this->id}_checkout"; |
| 397 |
} |
| 398 |
|
| 399 |
private function get_next_data_row_option_name() { |
| 400 |
$timestamp = $this->generate_option_name_timestamp(); |
| 401 |
|
| 402 |
// row iterator is used to avoid collisions where we're writing data waaay fast in a single process |
| 403 |
if ( $this->row_iterator === PHP_INT_MAX ) { |
| 404 |
$this->row_iterator = 0; |
| 405 |
} else { |
| 406 |
$this->row_iterator += 1; |
| 407 |
} |
| 408 |
|
| 409 |
return 'jpsq_' . $this->id . '-' . $timestamp . '-' . $this->random_int . '-' . $this->row_iterator; |
| 410 |
} |
| 411 |
|
| 412 |
private function fetch_items( $limit = null ) { |
| 413 |
global $wpdb; |
| 414 |
|
| 415 |
if ( $limit ) { |
| 416 |
$query_sql = $wpdb->prepare( "SELECT option_name AS id, option_value AS value FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT %d", "jpsq_{$this->id}-%", $limit ); |
| 417 |
} else { |
| 418 |
$query_sql = $wpdb->prepare( "SELECT option_name AS id, option_value AS value FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC", "jpsq_{$this->id}-%" ); |
| 419 |
} |
| 420 |
|
| 421 |
$items = $wpdb->get_results( $query_sql, OBJECT ); |
| 422 |
foreach ( $items as $item ) { |
| 423 |
$item->value = maybe_unserialize( $item->value ); |
| 424 |
} |
| 425 |
|
| 426 |
return $items; |
| 427 |
} |
| 428 |
|
| 429 |
private function validate_checkout( $buffer ) { |
| 430 |
if ( ! $buffer instanceof Jetpack_Sync_Queue_Buffer ) { |
| 431 |
return new WP_Error( 'not_a_buffer', 'You must checkin an instance of Jetpack_Sync_Queue_Buffer' ); |
| 432 |
} |
| 433 |
|
| 434 |
$checkout_id = $this->get_checkout_id(); |
| 435 |
|
| 436 |
if ( ! $checkout_id ) { |
| 437 |
return new WP_Error( 'buffer_not_checked_out', 'There are no checked out buffers' ); |
| 438 |
} |
| 439 |
|
| 440 |
if ( $checkout_id != $buffer->id ) { |
| 441 |
return new WP_Error( 'buffer_mismatch', 'The buffer you checked in was not checked out' ); |
| 442 |
} |
| 443 |
|
| 444 |
return true; |
| 445 |
} |
| 446 |
} |
| 447 |
|
| 448 |
class Jetpack_Sync_Utils { |
| 449 |
|
| 450 |
static function get_item_values( $items ) { |
| 451 |
return array_map( array( __CLASS__, 'get_item_value' ), $items ); |
| 452 |
} |
| 453 |
|
| 454 |
static function get_item_ids( $items ) { |
| 455 |
return array_map( array( __CLASS__, 'get_item_id' ), $items ); |
| 456 |
} |
| 457 |
|
| 458 |
static private function get_item_value( $item ) { |
| 459 |
return $item->value; |
| 460 |
} |
| 461 |
|
| 462 |
static private function get_item_id( $item ) { |
| 463 |
return $item->id; |
| 464 |
} |
| 465 |
} |
| 466 |
|
