perf(files): cache the mimetype table

lib/private/Files/Type/Loader.php

@@ -12,6 +12,8 @@
 use OCP\AppFramework\Db\TTransactional;
 use OCP\DB\Exception as DBException;
 use OCP\Files\IMimeTypeLoader;
+use OCP\ICache;
+use OCP\ICacheFactory;
 use OCP\IDBConnection;
 
 /**
@@ -28,14 +30,16 @@ class Loader implements IMimeTypeLoader {
 	/** @psalm-var array<string, int> */
 	protected array $mimetypeIds;
 
-	/**
-	 * @param IDBConnection $dbConnection
-	 */
+	private bool $loadedFromDatabase = false;
+	private ICache $cache;
+
 	public function __construct(
 		private IDBConnection $dbConnection,
+		ICacheFactory $cacheFactory,
 	) {
 		$this->mimetypes = [];
 		$this->mimetypeIds = [];
+		$this->cache = $cacheFactory->createLocal('mimetypes');
 	}
 
 	/**
@@ -46,24 +50,21 @@ public function getMimetypeById(int $id): ?string {
 		if (!$this->mimetypes) {
 			$this->loadMimetypes();
 		}
-		if (isset($this->mimetypes[$id])) {
-			return $this->mimetypes[$id];
+		if (!isset($this->mimetypes[$id]) && !$this->loadedFromDatabase) {
+			$this->loadMimetypes(true);
 		}
-		return null;
+		return $this->mimetypes[$id] ?? null;
 	}
 
 	/**
 	 * Get a mimetype ID, adding the mimetype to the DB if it does not exist
 	 */
 	#[\Override]
 	public function getId(string $mimetype): int {
-		if (!$this->mimetypeIds) {
-			$this->loadMimetypes();
-		}
-		if (isset($this->mimetypeIds[$mimetype])) {
-			return $this->mimetypeIds[$mimetype];
+		if (!$this->exists($mimetype)) {
+			return $this->store($mimetype);
 		}
-		return $this->store($mimetype);
+		return $this->mimetypeIds[$mimetype];
 	}
 
 	/**
@@ -74,6 +75,9 @@ public function exists(string $mimetype): bool {
 		if (!$this->mimetypeIds) {
 			$this->loadMimetypes();
 		}
+		if (!isset($this->mimetypeIds[$mimetype]) && !$this->loadedFromDatabase) {
+			$this->loadMimetypes(true);
+		}
 		return isset($this->mimetypeIds[$mimetype]);
 	}
 
@@ -84,6 +88,8 @@ public function exists(string $mimetype): bool {
 	public function reset(): void {
 		$this->mimetypes = [];
 		$this->mimetypeIds = [];
+		$this->loadedFromDatabase = false;
+		$this->cache->remove('mimetypes');
 	}
 
 	/**
@@ -124,25 +130,33 @@ protected function store(string $mimetype): int {
 
 		$this->mimetypes[$mimetypeId] = $mimetype;
 		$this->mimetypeIds[$mimetype] = $mimetypeId;
+		$this->cache->remove('mimetypes');
 		return $mimetypeId;
 	}
 
 	/**
-	 * Load all mimetypes from DB
+	 * Load all mimetypes, from the cache unless $fromDatabase is set. Mimetypes
+	 * are only ever added, so the cache can only miss new ones, which are
+	 * then loaded from the database.
 	 */
-	private function loadMimetypes(): void {
-		$qb = $this->dbConnection->getQueryBuilder();
-		$qb->select('id', 'mimetype')
-			->from('mimetypes');
-
-		$result = $qb->executeQuery();
-		$results = $result->fetchAllAssociative();
-		$result->closeCursor();
-
-		foreach ($results as $row) {
-			$this->mimetypes[(int)$row['id']] = $row['mimetype'];
-			$this->mimetypeIds[$row['mimetype']] = (int)$row['id'];
+	private function loadMimetypes(bool $fromDatabase = false): void {
+		$mimetypes = $fromDatabase ? null : $this->cache->get('mimetypes');
+		if (!is_array($mimetypes)) {
+			$qb = $this->dbConnection->getQueryBuilder();
+			$qb->select('id', 'mimetype')
+				->from('mimetypes');
+			$result = $qb->executeQuery();
+			$mimetypes = [];
+			foreach ($result->fetchAllAssociative() as $row) {
+				$mimetypes[(int)$row['id']] = (string)$row['mimetype'];
+			}
+			$result->closeCursor();
+			$this->cache->set('mimetypes', $mimetypes);
+			$this->loadedFromDatabase = true;
 		}
+
+		$this->mimetypes = $mimetypes;
+		$this->mimetypeIds = array_flip($mimetypes);
 	}
 
 	/**

tests/lib/Files/Type/LoaderTest.php

@@ -9,6 +9,8 @@
 namespace Test\Files\Type;
 
 use OC\Files\Type\Loader;
+use OC\Memcache\ArrayCache;
+use OCP\ICacheFactory;
 use OCP\IDBConnection;
 use OCP\Server;
 use PHPUnit\Framework\Attributes\Group;
@@ -17,14 +19,16 @@
 #[Group('DB')]
 class LoaderTest extends TestCase {
 	protected IDBConnection $db;
+	protected ArrayCache $cache;
 	protected Loader $loader;
 
 	#[\Override]
 	protected function setUp(): void {
 		parent::setUp();
 
 		$this->db = Server::get(IDBConnection::class);
-		$this->loader = new Loader($this->db);
+		$this->cache = new ArrayCache('');
+		$this->loader = $this->createLoader();
 	}
 
 	#[\Override]
@@ -35,6 +39,7 @@ protected function tearDown(): void {
 				'mimetype', $deleteMimetypes->createPositionalParameter('testing/%')
 			));
 		$deleteMimetypes->executeStatement();
+		$this->loader->reset();
 		parent::tearDown();
 	}
 
@@ -84,4 +89,42 @@ public function testStoreExists(): void {
 
 		$this->assertEquals($mimetypeId, $mimetypeId2);
 	}
+
+	private function createLoader(): Loader {
+		$cacheFactory = $this->createMock(ICacheFactory::class);
+		$cacheFactory->method('createLocal')->willReturn($this->cache);
+		return new Loader($this->db, $cacheFactory);
+	}
+
+	private function insertMimetype(string $mimetype): int {
+		$qb = $this->db->getQueryBuilder();
+		$qb->insert('mimetypes')
+			->values(['mimetype' => $qb->createPositionalParameter($mimetype)])
+			->executeStatement();
+		return $qb->getLastInsertId();
+	}
+
+	public function testMimetypesAreLoadedFromTheCache(): void {
+		$this->cache->set('mimetypes', [123456 => 'testing/cached']);
+
+		$this->assertSame('testing/cached', $this->createLoader()->getMimetypeById(123456));
+	}
+
+	public function testMimetypeMissingInTheCacheIsLoadedFromTheDatabase(): void {
+		$this->loader->getMimetypeById(1);
+		$id = $this->insertMimetype('testing/added-elsewhere');
+
+		$loader = $this->createLoader();
+		$this->assertSame('testing/added-elsewhere', $loader->getMimetypeById($id));
+		$this->assertTrue($loader->exists('testing/added-elsewhere'));
+		$this->assertSame($id, $loader->getId('testing/added-elsewhere'));
+	}
+
+	public function testStoreInvalidatesTheCache(): void {
+		$this->loader->getMimetypeById(1);
+		$this->assertTrue($this->cache->hasKey('mimetypes'));
+
+		$this->loader->getId('testing/stored');
+		$this->assertFalse($this->cache->hasKey('mimetypes'));
+	}
 }