feat(taskprocessing): Add queue_stats API endpoint for external autoscalers

core/Controller/TaskProcessingApiController.php

@@ -424,6 +424,42 @@ public function listTasks(?string $taskType, ?string $customId = null): DataResp
 		}
 	}
 
+	/**
+	 * Returns queue statistics for task processing
+	 *
+	 * Returns the count of scheduled and running tasks, optionally filtered
+	 * by task type(s). Designed for external scalers (e.g. KEDA) to poll
+	 * for task queue depth. Admin-only endpoint authenticated via app_password.
+	 *
+	 * @param string|null $taskTypeId Comma-separated list of task type IDs to filter by
+	 * @return DataResponse<Http::STATUS_OK, array{scheduled: int, running: int}, array{}>|DataResponse<Http::STATUS_INTERNAL_SERVER_ERROR, array{message: string}, array{}>
+	 *
+	 * 200: Queue stats returned
+	 */
+	#[NoCSRFRequired]
+	#[ApiRoute(verb: 'GET', url: '/queue_stats', root: '/taskprocessing')]
+	public function queueStats(?string $taskTypeId = null): DataResponse {
+		# TODO: bruteforce protection?
+		try {
+			$taskTypeIds = [];
+			if ($taskTypeId !== null) {
+				$taskTypeIds = array_map('trim', explode(',', $taskTypeId));
+				$taskTypeIds = array_filter($taskTypeIds, fn (string $id) => $id !== '');
+				$taskTypeIds = array_values($taskTypeIds);
+			}
+
+			$scheduled = $this->taskProcessingManager->countTasks(Task::STATUS_SCHEDULED, $taskTypeIds);
+			$running = $this->taskProcessingManager->countTasks(Task::STATUS_RUNNING, $taskTypeIds);
+
+			return new DataResponse([
+				'scheduled' => $scheduled,
+				'running' => $running,
+			]);
+		} catch (Exception) {
+			return new DataResponse(['message' => $this->l->t('Internal error')], Http::STATUS_INTERNAL_SERVER_ERROR);
+		}
+	}
+
 	/**
 	 * Returns the contents of a file referenced in a task
 	 *

lib/private/TaskProcessing/Db/TaskMapper.php

@@ -265,6 +265,26 @@ public function findNOldestScheduledByType(array $taskTypes, array $taskIdsToIgn
 		return $this->findEntities($qb);
 	}
 
+	/**
+	 * @param list<string> $taskTypeIds
+	 * @param int $status
+	 * @return int
+	 * @throws Exception
+	 */
+	public function countByStatus(array $taskTypeIds, int $status): int {
+		$qb = $this->db->getQueryBuilder();
+		$qb->select($qb->func()->count('id'))
+			->from($this->tableName)
+			->where($qb->expr()->eq('status', $qb->createNamedParameter($status, IQueryBuilder::PARAM_INT)));
+		if (!empty($taskTypeIds)) {
+			$qb->andWhere($qb->expr()->in('type', $qb->createNamedParameter($taskTypeIds, IQueryBuilder::PARAM_STR_ARRAY)));
+		}
+		$result = $qb->executeQuery();
+		$count = (int)$result->fetchOne();
+		$result->closeCursor();
+		return $count;
+	}
+
 	/**
 	 * @throws Exception
 	 */

lib/private/TaskProcessing/Manager.php

@@ -1357,6 +1357,14 @@ public function getTasks(
 		}
 	}
 
+	public function countTasks(int $status, array $taskTypeIds = []): int {
+		try {
+			return $this->taskMapper->countByStatus($taskTypeIds, $status);
+		} catch (\OCP\DB\Exception $e) {
+			throw new \OCP\TaskProcessing\Exception\Exception('There was a problem counting the tasks', 0, $e);
+		}
+	}
+
 	public function getUserTasksByApp(?string $userId, string $appId, ?string $customId = null): array {
 		try {
 			$taskEntities = $this->taskMapper->findUserTasksByApp($userId, $appId, $customId);

lib/public/TaskProcessing/IManager.php

@@ -258,6 +258,17 @@ public function lockTask(Task $task): bool;
 	 */
 	public function setTaskStatus(Task $task, int $status): void;
 
+	/**
+	 * Get the count of tasks filtered by status and optionally by task type(s)
+	 *
+	 * @param int $status The task status to filter by
+	 * @param list<string> $taskTypeIds Optional list of task type IDs to filter by
+	 * @return int The count of matching tasks
+	 * @throws Exception If the query failed
+	 * @since 34.0.0
+	 */
+	public function countTasks(int $status, array $taskTypeIds = []): int;
+
 	/**
 	 * Extract all input and output file IDs from a task
 	 *