1 files changed, 177 insertions, 0 deletions
diff --git a/www/wiki/extensions/SemanticMediaWiki/src/CachedPropertyValuesPrefetcher.php b/www/wiki/extensions/SemanticMediaWiki/src/CachedPropertyValuesPrefetcher.php
new file mode 100644
index 00000000..873a887f
--- /dev/null
+++ b/www/wiki/extensions/SemanticMediaWiki/src/CachedPropertyValuesPrefetcher.php
@@ -0,0 +1,177 @@
+<?php
+
+namespace SMW;
+
+use Onoi\BlobStore\BlobStore;
+use SMWQuery as Query;
+
+/**
+ * This class should be accessed via ApplicationFactory::getCachedPropertyValuesPrefetcher
+ * to ensure a singleton instance.
+ *
+ * The purpose of this class is to give fragmented access to frequent (hence
+ * cacheable) property values to ensure that the store is only used for when a
+ * match can not be found and so freeing up the capacities that can equally be
+ * served from a persistent cache instance.
+ *
+ * It is expected that as soon as the "on.before.semanticdata.update.complete"
+ * event has been emitted that matchable cache entries are purged for the
+ * subject in question.
+ *
+ * @license GNU GPL v2+
+ * @since 2.4
+ *
+ * @author mwjames
+ */
+class CachedPropertyValuesPrefetcher {
+
+	/**
+	 * @var string
+	 */
+	const VERSION = '0.4.1';
+
+	/**
+	 * Namespace occupied by the BlobStore
+	 */
+	const CACHE_NAMESPACE = 'smw:pvp:store';
+
+	/**
+	 * @var Store
+	 */
+	private $store;
+
+	/**
+	 * @var BlobStore
+	 */
+	private $blobStore;
+
+	/**
+	 * @var boolean
+	 */
+	private $disableCache = false;
+
+	/**
+	 * @since 2.4
+	 *
+	 * @param Store $store
+	 * @param BlobStore $blobStore
+	 */
+	public function __construct( Store $store, BlobStore $blobStore ) {
+		$this->store = $store;
+		$this->blobStore = $blobStore;
+	}
+
+	/**
+	 * @since 2.4
+	 */
+	public function resetCacheBy( DIWikiPage $subject ) {
+		$this->blobStore->delete( $this->getRootHashFrom( $subject ) );
+	}
+
+	/**
+	 * @since 3.0
+	 *
+	 * @param boolean $disableCache
+	 */
+	public function disableCache( $disableCache ) {
+		$this->disableCache = (bool)$disableCache;
+	}
+
+	/**
+	 * @since 2.4
+	 *
+	 * @param DIWikiPage $subject
+	 * @param DIProperty $property
+	 * @param RequestOptions|null $requestOptions
+	 *
+	 * @return array
+	 */
+	public function getPropertyValues( DIWikiPage $subject, DIProperty $property, RequestOptions $requestOptions = null ) {
+
+		// Items are collected as part of the subject hash so that any request is
+		// stored with that entity identifier allowing it to be evicted entirely
+		// when the subject is changed.
+		//
+		// The key on the other hand represent an individual request identifier
+		// that is stored as part of the overall cache item but making distinct
+		// requests possible, yet is fetched as part of the overall subject to
+		// minimize cache fragmentation and a better eviction strategy.
+		$key = $property->getKey() .
+			':' . $subject->getSubobjectName() .
+			':' . ( $requestOptions !== null ? md5( $requestOptions->getHash() ) : null );
+
+		$container = $this->blobStore->read(
+			$this->getRootHashFrom( $subject )
+		);
+
+		if ( $this->disableCache === false && $container->has( $key ) ) {
+			return $container->get( $key );
+		}
+
+		$dataItems = $this->store->getPropertyValues(
+			$subject,
+			$property,
+			$requestOptions
+		);
+
+		$container->set( $key, $dataItems );
+
+		$this->blobStore->save(
+			$container
+		);
+
+		return $dataItems;
+	}
+
+	/**
+	 * @since 2.4
+	 *
+	 * @param Query $query
+	 *
+	 * @return array
+	 */
+	public function queryPropertyValuesFor( Query $query ) {
+		return $this->store->getQueryResult( $query )->getResults();
+	}
+
+	/**
+	 * @since 2.4
+	 *
+	 * @return BlobStore
+	 */
+	public function getBlobStore() {
+		return $this->blobStore;
+	}
+
+	/**
+	 * @since 2.4
+	 *
+	 * @return Store
+	 */
+	public function getStore() {
+		return $this->store;
+	}
+
+	/**
+	 * @since 2.4
+	 *
+	 * @param DIWikiPage $subject
+	 *
+	 * @return string
+	 */
+	public function getRootHashFrom( DIWikiPage $subject ) {
+		return md5( $subject->asBase()->getHash() . self::VERSION );
+	}
+
+	/**
+	 * @since 2.4
+	 *
+	 * @param string $hash
+	 *
+	 * @return string
+	 */
+	public function createHashFromString( $hash ) {
+		return md5( $hash . self::VERSION );
+	}
+
+}