wikimedia/mediawiki-extensions-Wikibase

<?php

declare( strict_types = 1 );

namespace Wikibase\Lib\Store;

use Wikibase\DataModel\Entity\ItemId;
use Wikibase\DataModel\SiteLink;
use Wikimedia\ObjectCache\BagOStuff;

/**
 * SiteLinkLookup implementation that caches the obtained data (except for data obtained
 * via "getLinks").
 * Note: This doesn't implement any means of purging or data invalidation beyond the cache
 * timeout.
 *
 * @license GPL-2.0-or-later
 * @author Marius Hoch < hoo@online.de >
 */
class CachingSiteLinkLookup implements SiteLinkLookup {

    /**
     * @var SiteLinkLookup
     */
    private $lookup;

    /**
     * The cache to use for caching entities.
     *
     * @var BagOStuff
     */
    private $cache;

    /**
     * @var int
     */
    private $cacheDuration;

    /**
     * @var string
     */
    private $cacheKeyPrefix;

    /**
     * @param SiteLinkLookup $siteLinkLookup The lookup to use
     * @param BagOStuff $cache The cache to use
     * @param int $cacheDuration Cache duration in seconds. Defaults to 3600 (1 hour).
     * @param string $cacheKeyPrefix Cache key prefix to use.
     *     Important in case we're not in-process caching. Defaults to "wikibase"
     */
    public function __construct(
        SiteLinkLookup $siteLinkLookup,
        BagOStuff $cache,
        $cacheDuration = 3600,
        $cacheKeyPrefix = 'wikibase'
    ) {
        $this->lookup = $siteLinkLookup;
        $this->cache = $cache;
        $this->cacheDuration = $cacheDuration;
        $this->cacheKeyPrefix = $cacheKeyPrefix;
    }

    public function getItemIdForLink( string $globalSiteId, string $pageTitle ): ?ItemId {
        $itemIdSerialization = $this->cache->get( $this->getByPageCacheKey( $globalSiteId, $pageTitle ) );

        if ( is_string( $itemIdSerialization ) ) {
            return new ItemId( $itemIdSerialization );
        } elseif ( $itemIdSerialization === false ) {
            return $this->getAndCacheItemIdForLink( $globalSiteId, $pageTitle );
        }

        return null;
    }

    /**
     * This is uncached!
     */
    public function getLinks(
        ?array $numericIds = null,
        ?array $siteIds = null,
        ?array $pageNames = null
    ): array {
        // Caching this would be rather complicated for little to no benefit.
        return $this->lookup->getLinks( $numericIds, $siteIds, $pageNames );
    }

    /**
     * Returns an array of SiteLink objects for an item. If the item isn't known or not an Item,
     * an empty array is returned.
     *
     * @param ItemId $itemId
     *
     * @return SiteLink[]
     */
    public function getSiteLinksForItem( ItemId $itemId ): array {
        $cacheKey = $this->cacheKeyPrefix . ':sitelinks:' . $itemId->getSerialization();
        $siteLinks = $this->cache->get( $cacheKey );

        if ( !is_array( $siteLinks ) ) {
            $siteLinks = $this->lookup->getSiteLinksForItem( $itemId );
            $this->cache->set( $cacheKey, $siteLinks, $this->cacheDuration );
        }

        return $siteLinks;
    }

    public function getItemIdForSiteLink( SiteLink $siteLink ): ?ItemId {
        return $this->getItemIdForLink(
            $siteLink->getSiteId(),
            $siteLink->getPageName()
        );
    }

    private function getByPageCacheKey( string $globalSiteId, string $pageTitle ): string {
        return $this->cacheKeyPrefix . ':sitelinks-by-page:' . $globalSiteId . ':' . $pageTitle;
    }

    private function getAndCacheItemIdForLink( string $globalSiteId, string $pageTitle ): ?ItemId {
        $itemId = $this->lookup->getItemIdForLink( $globalSiteId, $pageTitle );

        $this->cache->set(
            $this->getByPageCacheKey( $globalSiteId, $pageTitle ),
            $itemId instanceof ItemId ? $itemId->getSerialization() : null,
            $this->cacheDuration
        );

        return $itemId;
    }

}