PoolCounter.php

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<?php
abstract class PoolCounter {
    /* Return codes */
    const LOCKED = 1; /* Lock acquired */
    const RELEASED = 2; /* Lock released */
    const DONE = 3; /* Another worker did the work for you */

    const ERROR = -1; /* Indeterminate error */
    const NOT_LOCKED = -2; /* Called release() with no lock held */
    const QUEUE_FULL = -3; /* There are already maxqueue workers on this lock */
    const TIMEOUT = -4; /* Timeout exceeded */
    const LOCK_HELD = -5; /* Cannot acquire another lock while you have one lock held */

    protected $key;
    protected $workers;
    protected $slots = 0;
    protected $maxqueue;
    protected $timeout;

    protected function __construct( $conf, $type, $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;
    }

    public static function factory( $type, $key ) {
        global $wgPoolCounterConf;
        if ( !isset( $wgPoolCounterConf[$type] ) ) {
            return new PoolCounter_Stub;
        }
        $conf = $wgPoolCounterConf[$type];
        $class = $conf['class'];

        return new $class( $conf, $type, $key );
    }

    public function getKey() {
        return $this->key;
    }

    abstract public function acquireForMe();

    abstract public function acquireForAnyone();

    abstract public function release();

    protected function hashKeyIntoSlots( $key, $slots ) {
        return hexdec( substr( sha1( $key ), 0, 4 ) ) % $slots;
    }
}

// @codingStandardsIgnoreStart Squiz.Classes.ValidClassName.NotCamelCaps
class PoolCounter_Stub extends PoolCounter {
    // @codingStandardsIgnoreEnd

    public function __construct() {
        /* No parameters needed */
    }

    public function acquireForMe() {
        return Status::newGood( PoolCounter::LOCKED );
    }

    public function acquireForAnyone() {
        return Status::newGood( PoolCounter::LOCKED );
    }

    public function release() {
        return Status::newGood( PoolCounter::RELEASED );
    }
}