/** @var string All workers with the same key share the lock */
protected $key;
- /** @var int Maximum number of workers doing the task simultaneously */
+ /** @var int Maximum number of workers working on tasks with the same key simultaneously */
protected $workers;
+ /**
+ * Maximum number of workers working on this task type, regardless of key.
+ * 0 means unlimited. Max allowed value is 65536.
+ * The way the slot limit is enforced is overzealous - this option should be used with caution.
+ * @var int
+ */
+ protected $slots = 0;
/** @var int If this number of workers are already working/waiting, fail instead of wait */
protected $maxqueue;
/** @var float Maximum time in seconds to wait for the lock */
* @param string $key
*/
protected function __construct( $conf, $type, $key ) {
- $this->key = $key;
$this->workers = $conf['workers'];
$this->maxqueue = $conf['maxqueue'];
$this->timeout = $conf['timeout'];
+ if ( isset( $conf['slots'] ) ) {
+ $this->slots = $conf['slots'];
+ }
+
+ if ( $this->slots ) {
+ $key = $this->hashKeyIntoSlots( $key, $this->slots );
+ }
+ $this->key = $key;
}
/**
* @return Status value is one of Released/NotLocked/Error
*/
abstract public function release();
+
+ /**
+ * Given a key (any string) and the number of lots, returns a slot number (an integer from the [0..($slots-1)] range).
+ * This is used for a global limit on the number of instances of a given type that can acquire a lock.
+ * The hashing is deterministic so that PoolCounter::$workers is always an upper limit of how many instances with
+ * the same key can acquire a lock.
+ *
+ * @param string $key PoolCounter instance key (any string)
+ * @param int $slots the number of slots (max allowed value is 65536)
+ * @return int
+ */
+ protected function hashKeyIntoSlots( $key, $slots ) {
+ return hexdec( substr( sha1( $key ), 0, 4 ) ) % $slots;
+ }
}
// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps