Merge pull request #42707 from nextcloud/enh/noid/store-file-etag-at-metadata-creation

enh(metadata): store current file etag

apps/dav/lib/Connector/Sabre/FilesPlugin.php

 							$metadata->setArray($metadataKey, $value);
 							break;
 						case IMetadataValueWrapper::TYPE_STRING_LIST:
-							$metadata->setStringList(
-								$metadataKey, $value, $knownMetadata->isIndex($metadataKey)
-							);
+							$metadata->setStringList($metadataKey, $value, $knownMetadata->isIndex($metadataKey));
 							break;
 						case IMetadataValueWrapper::TYPE_INT_LIST:
-							$metadata->setIntList(
-								$metadataKey, $value, $knownMetadata->isIndex($metadataKey)
-							);
+							$metadata->setIntList($metadataKey, $value, $knownMetadata->isIndex($metadataKey));
 							break;
 					}
 

lib/private/Blurhash/Listener/GenerateBlurhashMetadata.php

 			return;
 		}
 
+		$currentEtag = $file->getEtag();
+		$metadata = $event->getMetadata();
+		if ($metadata->getEtag('blurhash') === $currentEtag) {
+			return;
+		}
+
 		// too heavy to run on the live thread, request a rerun as a background job
 		if ($event instanceof MetadataLiveEvent) {
 			$event->requestBackgroundJob();
 			return;
 		}
 
-		$metadata = $event->getMetadata();
-		$metadata->setString('blurhash', $this->generateBlurHash($image));
+		$metadata->setString('blurhash', $this->generateBlurHash($image))
+				 ->setEtag('blurhash', $currentEtag);
 	}
 
 	/**

lib/private/FilesMetadata/Model/FilesMetadata.php

 		$this->metadata[$key]->setEditPermission($permission);
 	}
 
+
+	public function getEtag(string $key): string {
+		if (!array_key_exists($key, $this->metadata)) {
+			throw new FilesMetadataNotFoundException();
+		}
+
+		return $this->metadata[$key]->getEtag();
+	}
+
+	public function setEtag(string $key, string $etag): void {
+		if (!array_key_exists($key, $this->metadata)) {
+			throw new FilesMetadataNotFoundException();
+		}
+
+		$this->metadata[$key]->setEtag($etag);
+	}
+
 	/**
 	 * @param string $key metadata key
 	 *

lib/private/FilesMetadata/Model/MetadataValueWrapper.php

 	private string $type;
 	/** @var string|int|float|bool|array|string[]|int[] */
 	private mixed $value = null;
+	private string $etag = '';
 	private bool $indexed = false;
 	private int $editPermission = self::EDIT_FORBIDDEN;
 
 		return $this->value;
 	}
 
+	/**
+	 * @inheritDoc
+	 * @return string stored etag
+	 * @since 29.0.0
+	 */
+	public function getEtag(): string {
+		return $this->etag;
+	}
+
+	/**
+	 * @param string $etag etag value
+	 *
+	 * @inheritDoc
+	 * @return self
+	 * @since 29.0.0
+	 */
+	public function setEtag(string $etag): self {
+		$this->etag = $etag;
+		return $this;
+	}
+
 	/**
 	 * @param bool $indexed TRUE to set the stored value as an indexed value
 	 *
 	public function import(array $data): self {
 		$this->value = $data['value'] ?? null;
 		$this->type = $data['type'] ?? '';
+		$this->setEtag($data['etag'] ?? '');
 		$this->setIndexed($data['indexed'] ?? false);
 		$this->setEditPermission($data['editPermission'] ?? self::EDIT_FORBIDDEN);
 		return $this;
 		return [
 			'value' => ($emptyValues) ? null : $this->value,
 			'type' => $this->getType(),
+			'etag' => $this->getEtag(),
 			'indexed' => $this->isIndexed(),
 			'editPermission' => $this->getEditPermission()
 		];

lib/private/FilesMetadata/Service/MetadataRequestService.php

 		try {
 			$qb = $this->dbConnection->getQueryBuilder();
 			$qb->select('json', 'sync_token')->from(self::TABLE_METADATA);
-			$qb->where(
-				$qb->expr()->eq('file_id', $qb->createNamedParameter($fileId, IQueryBuilder::PARAM_INT))
-			);
+			$qb->where($qb->expr()->eq('file_id', $qb->createNamedParameter($fileId, IQueryBuilder::PARAM_INT)));
 			$result = $qb->executeQuery();
 			$data = $result->fetch();
 			$result->closeCursor();
 		} catch (Exception $e) {
-			$this->logger->warning(
-				'exception while getMetadataFromDatabase()', ['exception' => $e, 'fileId' => $fileId]
-			);
+			$this->logger->warning('exception while getMetadataFromDatabase()', ['exception' => $e, 'fileId' => $fileId]);
 			throw new FilesMetadataNotFoundException();
 		}
 
 	/**
 	 * returns metadata for multiple file ids
 	 *
-	 * If
-	 *
 	 * @param array $fileIds file ids
 	 *
 	 * @return array File ID is the array key, files without metadata are not returned in the array
 	public function getMetadataFromFileIds(array $fileIds): array {
 		$qb = $this->dbConnection->getQueryBuilder();
 		$qb->select('file_id', 'json', 'sync_token')->from(self::TABLE_METADATA);
-		$qb->where(
-			$qb->expr()->in('file_id', $qb->createNamedParameter($fileIds, IQueryBuilder::PARAM_INT_ARRAY))
-		);
+		$qb->where($qb->expr()->in('file_id', $qb->createNamedParameter($fileIds, IQueryBuilder::PARAM_INT_ARRAY)));
 
 		$list = [];
 		$result = $qb->executeQuery();

lib/public/FilesMetadata/Model/IFilesMetadata.php

  *   "mymeta": {
  *     "value": "this is a test",
  *     "type": "string",
+ *     "etag": "abcd1234",
  *     "indexed": false,
  *     "editPermission": 1
  *   },
  *   "myapp-anothermeta": {
  *     "value": 42,
  *     "type": "int",
+ *     "etag": "0987zyxw",
  *     "indexed": true,
  *     "editPermission": 0
  *   }
 	 */
 	public function isIndex(string $key): bool;
 
+	/**
+	 * returns file etag stored during the last update of the metadata key
+	 *
+	 * @param string $key metadata key
+	 * @return string
+	 * @since 29.0.0
+	 */
+	public function getEtag(string $key): string;
+
+	/**
+	 * set file etag
+	 *
+	 * @param string $key metadata key
+	 * @since 29.0.0
+	 */
+	public function setEtag(string $key, string $etag): void;
+
 	/**
 	 * set remote edit permission
 	 * (Webdav PROPPATCH)

lib/public/FilesMetadata/Model/IMetadataValueWrapper.php

 	 */
 	public function getValueAny(): mixed;
 
+	/**
+	 * get stored etag value
+	 *
+	 * @return string stored etag
+	 * @since 29.0.0
+	 */
+	public function getEtag(): string;
+
+	/**
+	 * set etag value
+	 *
+	 * @param string $etag etag value
+	 *
+	 * @return self
+	 * @since 29.0.0
+	 */
+	public function setEtag(string $etag): self;
+
 	/**
 	 * @param bool $indexed TRUE to set the stored value as an indexed value
 	 *