feat(preview): Make it possible to disable on preview migration

Signed-off-by: Carl Schwan <carlschwan@kde.org>

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 @@ class ConfigLexicon implements ILexicon {
 			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.'
+			),
 		];
 	}
 

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;
@@ -111,7 +112,7 @@ class Generator {
 
 		[$file->getId() => $previews] = $this->previewMapper->getAvailablePreviews([$file->getId()]);
 
-		if (empty($previews)) {
+		if (empty($previews) && $this->appConfig->getValueBool('core', ConfigLexicon::ON_DEMAND_PREVIEW_MIGRATION)) {
 			$previews = $this->migrateOldPreviews($file->getId());
 		}
 
@@ -201,7 +202,7 @@ class Generator {
 	}
 
 	/**
-	 * @return array<string|int, string[]>
+	 * @return Preview[]
 	 */
 	private function migrateOldPreviews(int $fileId): array {
 		if ($this->appConfig->getValueBool('core', 'previewMovedDone')) {