+ /**
+ * Get a cache key for a given Blob address.
+ *
+ * The cache key is constructed in a way that allows cached blobs from the same database
+ * to be re-used between wikis. For example, enwiki and frwiki will use the same cache keys
+ * for blobs from the wikidatawiki database.
+ *
+ * @param string $blobAddress
+ * @return string
+ */
+ private function getCacheKey( $blobAddress ) {
+ return $this->cache->makeGlobalKey(
+ 'BlobStore',
+ 'address',
+ $this->dbLoadBalancer->resolveDomainID( $this->wikiId ),
+ $blobAddress
+ );
+ }
+