wikimedia/mediawiki-extensions-TwnMainPage

<?php
/**
 * Classes for caching stat numbers.
 *
 * @file
 * @author Niklas Laxström
 * @license GPL-2.0-or-later
 */

use MediaWiki\MediaWikiServices;

/**
 * Simple wrapper over object cache that supports
 * serving stale data while triggering update in the
 * background. The JobQueue should avoid executing
 * cache update jobs in parallel.
 */
class CachedStat implements DeferrableUpdate {
    /// @var string
    protected $key;

    /// @var array
    protected $worker;

    /// @var int
    protected $staleAge;

    /// @var int
    protected $expiredAge;

    /// @var string
    protected $onMiss;

    /** @var BagOStuff */
    protected $cache;

    /**
     * @param string $key Unique key for these values.
     * @param int $staleAge Trigger background refresh job if values are older than this.
     * @param int $expiredAge Do not use values older than this.
     * @param array $worker Array with method and parameters.
     * @param string $onMiss What to do on cache miss. 'update' or 'allow miss'.
     */
    public function __construct( $key, $staleAge, $expiredAge, $worker, $onMiss = 'update' ) {
        $this->key = $key;
        $this->staleAge = $staleAge;
        $this->expiredAge = $expiredAge;
        $this->worker = $worker;
        $this->onMiss = $onMiss;

        $this->cache = ObjectCache::getInstance( CACHE_ANYTHING );
    }

    /** @internal For testing only */
    public function setCache( BagOStuff $cache ) {
        $this->cache = $cache;
    }

    public function doUpdate() {
        $params = $this->worker;
        $func = array_shift( $params );
        $value = call_user_func_array( $func, $params );

        $toStore = [
            'v' => $value,
            't' => wfTimestamp( TS_UNIX ),
        ];

        $this->cache->set( $this->getKey(), $toStore, $this->expiredAge );

        return $value;
    }

    public function get() {
        $value = $this->cache->get( $this->getKey() );

        if ( !is_array( $value ) ) {
            if ( $this->onMiss !== 'update' ) {
                MediaWikiServices::getInstance()->getJobQueueGroup()->push( $this->makeJob() );

                return null;
            } else {
                return $this->doUpdate();
            }
        }

        if ( $value['t'] + $this->staleAge < wfTimestamp( TS_UNIX ) ) {
            MediaWikiServices::getInstance()->getJobQueueGroup()->push( $this->makeJob() );
        }

        return $value['v'];
    }

    private function getKey(): string {
        return $this->cache->makeKey( __CLASS__, $this->key );
    }

    private function makeJob(): CachedStatJob {
        return CachedStatJob::newFromSpec(
            [
                'class' => self::class,
                'args' => [
                    $this->key,
                    $this->staleAge,
                    $this->expiredAge,
                    $this->worker,
                    $this->onMiss,
                ],
                'calls' => [ 'doUpdate' => [] ],
            ]
        );
    }
}