feat(preview): On demand preview migration

core/AppInfo/ConfigLexicon.php

@@ -38,6 +38,8 @@ class ConfigLexicon implements ILexicon {
 
 	public const LASTCRON_TIMESTAMP = 'lastcron';
 
+	public const ON_DEMAND_PREVIEW_MIGRATION = 'on_demand_preview_migration';
+
 	public function getStrictness(): Strictness {
 		return Strictness::IGNORE;
 	}
@@ -93,6 +95,12 @@ public function getAppConfigs(): array {
 			new Entry(self::OCM_INVITE_ACCEPT_DIALOG, ValueType::STRING, '', 'route to local invite accept dialog', note: 'set as empty string to disable feature'),
 			new Entry(self::UNIFIED_SEARCH_MIN_SEARCH_LENGTH, ValueType::INT, 1, 'Minimum search length to trigger the request', rename: 'unified-search.min-search-length'),
 			new Entry(self::UNIFIED_SEARCH_MAX_RESULTS_PER_REQUEST, ValueType::INT, 25, 'Maximum results returned per search request', rename: 'unified-search.max-results-per-request'),
+			new Entry(
+				key: self::ON_DEMAND_PREVIEW_MIGRATION,
+				type: ValueType::BOOL,
+				defaultRaw: true,
+				definition: 'Whether on demand preview migration is enabled.'
+			),
 		];
 	}
 

core/BackgroundJobs/PreviewMigrationJob.php

@@ -0,0 +1,107 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH
+ * SPDX-FileContributor: Carl Schwan
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\Core\BackgroundJobs;
+
+use OC\Preview\Db\Preview;
+use OC\Preview\PreviewMigrationService;
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\BackgroundJob\TimedJob;
+use OCP\DB\IResult;
+use OCP\Files\IRootFolder;
+use OCP\IAppConfig;
+use OCP\IConfig;
+use OCP\IDBConnection;
+use Override;
+
+class PreviewMigrationJob extends TimedJob {
+	private string $previewRootPath;
+
+	public function __construct(
+		ITimeFactory $time,
+		private readonly IAppConfig $appConfig,
+		private readonly IConfig $config,
+		private readonly IDBConnection $connection,
+		private readonly IRootFolder $rootFolder,
+		private readonly PreviewMigrationService $migrationService,
+	) {
+		parent::__construct($time);
+
+		$this->setTimeSensitivity(self::TIME_INSENSITIVE);
+		$this->setInterval(24 * 60 * 60);
+		$this->previewRootPath = 'appdata_' . $this->config->getSystemValueString('instanceid') . '/preview/';
+	}
+
+	#[Override]
+	protected function run(mixed $argument): void {
+		if ($this->appConfig->getValueBool('core', 'previewMovedDone')) {
+			return;
+		}
+
+		$startTime = time();
+		while (true) {
+			$qb = $this->connection->getQueryBuilder();
+			$qb->select('path')
+				->from('filecache')
+				// Hierarchical preview folder structure
+				->where($qb->expr()->like('path', $qb->createNamedParameter($this->previewRootPath . '%/%/%/%/%/%/%/%/%')))
+				// Legacy flat preview folder structure
+				->orWhere($qb->expr()->like('path', $qb->createNamedParameter($this->previewRootPath . '%/%.%')))
+				->hintShardKey('storage', $this->rootFolder->getMountPoint()->getNumericStorageId())
+				->setMaxResults(100);
+
+			$result = $qb->executeQuery();
+			$foundPreviews = $this->processQueryResult($result);
+
+			if (!$foundPreviews) {
+				break;
+			}
+
+			// Stop if execution time is more than one hour.
+			if (time() - $startTime > 3600) {
+				return;
+			}
+		}
+
+		$this->appConfig->setValueBool('core', 'previewMovedDone', true);
+	}
+
+	private function processQueryResult(IResult $result): bool {
+		$foundPreview = false;
+		$fileIds = [];
+		$flatFileIds = [];
+		while ($row = $result->fetch()) {
+			$pathSplit = explode('/', $row['path']);
+			assert(count($pathSplit) >= 2);
+			$fileId = (int)$pathSplit[count($pathSplit) - 2];
+			if (count($pathSplit) === 11) {
+				// Hierarchical structure
+				if (!in_array($fileId, $fileIds)) {
+					$fileIds[] = $fileId;
+				}
+			} else {
+				// Flat structure
+				if (!in_array($fileId, $flatFileIds)) {
+					$flatFileIds[] = $fileId;
+				}
+			}
+			$foundPreview = true;
+		}
+
+		foreach ($fileIds as $fileId) {
+			$this->migrationService->migrateFileId($fileId, flatPath: false);
+		}
+
+		foreach ($flatFileIds as $fileId) {
+			$this->migrationService->migrateFileId($fileId, flatPath: true);
+		}
+		return $foundPreview;
+	}
+}

lib/composer/composer/LICENSE

@@ -1,4 +1,3 @@
-
 Copyright (c) Nils Adermann, Jordi Boggiano
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -18,4 +17,3 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
-

lib/composer/composer/autoload_classmap.php

@@ -1299,7 +1299,7 @@
     'OC\\Core\\BackgroundJobs\\CleanupLoginFlowV2' => $baseDir . '/core/BackgroundJobs/CleanupLoginFlowV2.php',
     'OC\\Core\\BackgroundJobs\\GenerateMetadataJob' => $baseDir . '/core/BackgroundJobs/GenerateMetadataJob.php',
     'OC\\Core\\BackgroundJobs\\LookupServerSendCheckBackgroundJob' => $baseDir . '/core/BackgroundJobs/LookupServerSendCheckBackgroundJob.php',
-    'OC\\Core\\BackgroundJobs\\MovePreviewJob' => $baseDir . '/core/BackgroundJobs/MovePreviewJob.php',
+    'OC\\Core\\BackgroundJobs\\PreviewMigrationJob' => $baseDir . '/core/BackgroundJobs/PreviewMigrationJob.php',
     'OC\\Core\\Command\\App\\Disable' => $baseDir . '/core/Command/App/Disable.php',
     'OC\\Core\\Command\\App\\Enable' => $baseDir . '/core/Command/App/Enable.php',
     'OC\\Core\\Command\\App\\GetPath' => $baseDir . '/core/Command/App/GetPath.php',
@@ -1977,6 +1977,7 @@
     'OC\\Preview\\PNG' => $baseDir . '/lib/private/Preview/PNG.php',
     'OC\\Preview\\Photoshop' => $baseDir . '/lib/private/Preview/Photoshop.php',
     'OC\\Preview\\Postscript' => $baseDir . '/lib/private/Preview/Postscript.php',
+    'OC\\Preview\\PreviewMigrationService' => $baseDir . '/lib/private/Preview/PreviewMigrationService.php',
     'OC\\Preview\\PreviewService' => $baseDir . '/lib/private/Preview/PreviewService.php',
     'OC\\Preview\\ProviderV2' => $baseDir . '/lib/private/Preview/ProviderV2.php',
     'OC\\Preview\\SGI' => $baseDir . '/lib/private/Preview/SGI.php',

lib/composer/composer/autoload_static.php

@@ -1340,7 +1340,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OC\\Core\\BackgroundJobs\\CleanupLoginFlowV2' => __DIR__ . '/../../..' . '/core/BackgroundJobs/CleanupLoginFlowV2.php',
         'OC\\Core\\BackgroundJobs\\GenerateMetadataJob' => __DIR__ . '/../../..' . '/core/BackgroundJobs/GenerateMetadataJob.php',
         'OC\\Core\\BackgroundJobs\\LookupServerSendCheckBackgroundJob' => __DIR__ . '/../../..' . '/core/BackgroundJobs/LookupServerSendCheckBackgroundJob.php',
-        'OC\\Core\\BackgroundJobs\\MovePreviewJob' => __DIR__ . '/../../..' . '/core/BackgroundJobs/MovePreviewJob.php',
+        'OC\\Core\\BackgroundJobs\\PreviewMigrationJob' => __DIR__ . '/../../..' . '/core/BackgroundJobs/PreviewMigrationJob.php',
         'OC\\Core\\Command\\App\\Disable' => __DIR__ . '/../../..' . '/core/Command/App/Disable.php',
         'OC\\Core\\Command\\App\\Enable' => __DIR__ . '/../../..' . '/core/Command/App/Enable.php',
         'OC\\Core\\Command\\App\\GetPath' => __DIR__ . '/../../..' . '/core/Command/App/GetPath.php',
@@ -2018,6 +2018,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OC\\Preview\\PNG' => __DIR__ . '/../../..' . '/lib/private/Preview/PNG.php',
         'OC\\Preview\\Photoshop' => __DIR__ . '/../../..' . '/lib/private/Preview/Photoshop.php',
         'OC\\Preview\\Postscript' => __DIR__ . '/../../..' . '/lib/private/Preview/Postscript.php',
+        'OC\\Preview\\PreviewMigrationService' => __DIR__ . '/../../..' . '/lib/private/Preview/PreviewMigrationService.php',
         'OC\\Preview\\PreviewService' => __DIR__ . '/../../..' . '/lib/private/Preview/PreviewService.php',
         'OC\\Preview\\ProviderV2' => __DIR__ . '/../../..' . '/lib/private/Preview/ProviderV2.php',
         'OC\\Preview\\SGI' => __DIR__ . '/../../..' . '/lib/private/Preview/SGI.php',

lib/private/Preview/Generator.php

@@ -6,6 +6,7 @@
  */
 namespace OC\Preview;
 
+use OC\Core\AppInfo\ConfigLexicon;
 use OC\Preview\Db\Preview;
 use OC\Preview\Db\PreviewMapper;
 use OC\Preview\Storage\PreviewFile;
@@ -17,6 +18,7 @@
 use OCP\Files\NotPermittedException;
 use OCP\Files\SimpleFS\InMemoryFile;
 use OCP\Files\SimpleFS\ISimpleFile;
+use OCP\IAppConfig;
 use OCP\IConfig;
 use OCP\IImage;
 use OCP\IPreview;
@@ -30,13 +32,15 @@ class Generator {
 	public const SEMAPHORE_ID_NEW = 0x07ea;
 
 	public function __construct(
-		private IConfig $config,
-		private IPreview $previewManager,
-		private GeneratorHelper $helper,
-		private IEventDispatcher $eventDispatcher,
-		private LoggerInterface $logger,
-		private PreviewMapper $previewMapper,
-		private StorageFactory $storageFactory,
+		private readonly IConfig $config,
+		private readonly IAppConfig $appConfig,
+		private readonly IPreview $previewManager,
+		private readonly GeneratorHelper $helper,
+		private readonly IEventDispatcher $eventDispatcher,
+		private readonly LoggerInterface $logger,
+		private readonly PreviewMapper $previewMapper,
+		private readonly StorageFactory $storageFactory,
+		private readonly PreviewMigrationService $migrationService,
 	) {
 	}
 
@@ -108,6 +112,10 @@ public function generatePreviews(File $file, array $specifications, ?string $mim
 
 		[$file->getId() => $previews] = $this->previewMapper->getAvailablePreviews([$file->getId()]);
 
+		if (empty($previews) && $this->appConfig->getValueBool('core', ConfigLexicon::ON_DEMAND_PREVIEW_MIGRATION)) {
+			$previews = $this->migrateOldPreviews($file->getId());
+		}
+
 		$previewVersion = null;
 		if ($file instanceof IVersionedPreviewFile) {
 			$previewVersion = $file->getPreviewVersion();
@@ -193,6 +201,21 @@ public function generatePreviews(File $file, array $specifications, ?string $mim
 		return $previewFile;
 	}
 
+	/**
+	 * @return Preview[]
+	 */
+	private function migrateOldPreviews(int $fileId): array {
+		if ($this->appConfig->getValueBool('core', 'previewMovedDone')) {
+			return [];
+		}
+
+		$previews = $this->migrationService->migrateFileId($fileId, flatPath: false);
+		if (empty($previews)) {
+			$previews = $this->migrationService->migrateFileId($fileId, flatPath: true);
+		}
+		return $previews;
+	}
+
 	/**
 	 * Acquire a semaphore of the specified id and concurrency, blocking if necessary.
 	 * Return an identifier of the semaphore on success, which can be used to release it via