6 files changed, 204 insertions, 427 deletions

diff --git a/lib/private/BackgroundJob/Job.php b/lib/private/BackgroundJob/Job.php
deleted file mode 100644
index 399ff05134e..00000000000
--- a/lib/private/BackgroundJob/Job.php
+++ /dev/null
@@ -1,94 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Daniel Kesselberg <mail@danielkesselberg.de>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Noveen Sachdeva <noveen.sachdeva@research.iiit.ac.in>
- * @author Robin Appelman <robin@icewind.nl>
- * @author Thomas Müller <thomas.mueller@tmit.eu>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program. If not, see <http://www.gnu.org/licenses/>
- *
- */
-namespace OC\BackgroundJob;
-
-use OCP\BackgroundJob\IJob;
-use OCP\BackgroundJob\IJobList;
-use OCP\ILogger;
-
-/**
- * @deprecated internal class, use \OCP\BackgroundJob\Job
- */
-abstract class Job implements IJob {
-	/** @var int */
-	protected $id;
-
-	/** @var int */
-	protected $lastRun;
-
-	/** @var mixed */
-	protected $argument;
-
-	public function execute(IJobList $jobList, ILogger $logger = null) {
-		$jobList->setLastRun($this);
-		if ($logger === null) {
-			$logger = \OC::$server->getLogger();
-		}
-
-		try {
-			$jobStartTime = time();
-			$logger->debug('Run ' . get_class($this) . ' job with ID ' . $this->getId(), ['app' => 'cron']);
-			$this->run($this->argument);
-			$timeTaken = time() - $jobStartTime;
-
-			$logger->debug('Finished ' . get_class($this) . ' job with ID ' . $this->getId() . ' in ' . $timeTaken . ' seconds', ['app' => 'cron']);
-			$jobList->setExecutionTime($this, $timeTaken);
-		} catch (\Throwable $e) {
-			if ($logger) {
-				$logger->logException($e, [
-					'app' => 'core',
-					'message' => 'Error while running background job (class: ' . get_class($this) . ', arguments: ' . print_r($this->argument, true) . ')'
-				]);
-			}
-		}
-	}
-
-	abstract protected function run($argument);
-
-	public function setId(int $id) {
-		$this->id = $id;
-	}
-
-	public function setLastRun(int $lastRun) {
-		$this->lastRun = $lastRun;
-	}
-
-	public function setArgument($argument) {
-		$this->argument = $argument;
-	}
-
-	public function getId() {
-		return $this->id;
-	}
-
-	public function getLastRun() {
-		return $this->lastRun;
-	}
-
-	public function getArgument() {
-		return $this->argument;
-	}
-}
diff --git a/lib/private/BackgroundJob/JobList.php b/lib/private/BackgroundJob/JobList.php
index fe65a1879bc..c00a51e3851 100644
--- a/lib/private/BackgroundJob/JobList.php
+++ b/lib/private/BackgroundJob/JobList.php
@@ -1,77 +1,47 @@
 <?php
+
 /**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Christoph Wurst <christoph@winzerhof-wurst.at>
- * @author Georg Ehrke <oc.list@georgehrke.com>
- * @author Joas Schilling <coding@schilljs.com>
- * @author Jörn Friedrich Dreyer <jfd@butonic.de>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Noveen Sachdeva <noveen.sachdeva@research.iiit.ac.in>
- * @author Robin Appelman <robin@icewind.nl>
- * @author Robin McCorkell <robin@mccorkell.me.uk>
- * @author Roeland Jago Douma <roeland@famdouma.nl>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program. If not, see <http://www.gnu.org/licenses/>
- *
+ * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
+ * SPDX-License-Identifier: AGPL-3.0-only
  */
 namespace OC\BackgroundJob;
 
-use Doctrine\DBAL\Platforms\MySQLPlatform;
 use OCP\AppFramework\QueryException;
 use OCP\AppFramework\Utility\ITimeFactory;
 use OCP\AutoloadNotAllowedException;
 use OCP\BackgroundJob\IJob;
 use OCP\BackgroundJob\IJobList;
+use OCP\BackgroundJob\IParallelAwareJob;
+use OCP\DB\Exception;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IConfig;
 use OCP\IDBConnection;
+use Psr\Log\LoggerInterface;
+use function get_class;
+use function json_encode;
+use function min;
+use function strlen;
 
 class JobList implements IJobList {
-
-	/** @var IDBConnection */
-	protected $connection;
-
-	/**@var IConfig */
-	protected $config;
-
-	/**@var ITimeFactory */
-	protected $timeFactory;
-
-	/**
-	 * @param IDBConnection $connection
-	 * @param IConfig $config
-	 * @param ITimeFactory $timeFactory
-	 */
-	public function __construct(IDBConnection $connection, IConfig $config, ITimeFactory $timeFactory) {
-		$this->connection = $connection;
-		$this->config = $config;
-		$this->timeFactory = $timeFactory;
+	/** @var array<string, int> */
+	protected array $alreadyVisitedParallelBlocked = [];
+
+	public function __construct(
+		protected IDBConnection $connection,
+		protected IConfig $config,
+		protected ITimeFactory $timeFactory,
+		protected LoggerInterface $logger,
+	) {
 	}
 
-	/**
-	 * @param IJob|string $job
-	 * @param mixed $argument
-	 */
-	public function add($job, $argument = null) {
-		if ($job instanceof IJob) {
-			$class = get_class($job);
-		} else {
-			$class = $job;
+	public function add($job, $argument = null, ?int $firstCheck = null): void {
+		if ($firstCheck === null) {
+			$firstCheck = $this->timeFactory->getTime();
 		}
 
+		$class = ($job instanceof IJob) ? get_class($job) : $job;
+
 		$argumentJson = json_encode($argument);
 		if (strlen($argumentJson) > 4000) {
 			throw new \InvalidArgumentException('Background job arguments can\'t exceed 4000 characters (json encoded)');
@@ -83,127 +53,126 @@ class JobList implements IJobList {
 				->values([
 					'class' => $query->createNamedParameter($class),
 					'argument' => $query->createNamedParameter($argumentJson),
-					'argument_hash' => $query->createNamedParameter(md5($argumentJson)),
+					'argument_hash' => $query->createNamedParameter(hash('sha256', $argumentJson)),
 					'last_run' => $query->createNamedParameter(0, IQueryBuilder::PARAM_INT),
-					'last_checked' => $query->createNamedParameter($this->timeFactory->getTime(), IQueryBuilder::PARAM_INT),
+					'last_checked' => $query->createNamedParameter($firstCheck, IQueryBuilder::PARAM_INT),
 				]);
 		} else {
 			$query->update('jobs')
 				->set('reserved_at', $query->expr()->literal(0, IQueryBuilder::PARAM_INT))
-				->set('last_checked', $query->createNamedParameter($this->timeFactory->getTime(), IQueryBuilder::PARAM_INT))
+				->set('last_checked', $query->createNamedParameter($firstCheck, IQueryBuilder::PARAM_INT))
+				->set('last_run', $query->createNamedParameter(0, IQueryBuilder::PARAM_INT))
 				->where($query->expr()->eq('class', $query->createNamedParameter($class)))
-				->andWhere($query->expr()->eq('argument_hash', $query->createNamedParameter(md5($argumentJson))));
+				->andWhere($query->expr()->eq('argument_hash', $query->createNamedParameter(hash('sha256', $argumentJson))));
 		}
 		$query->executeStatement();
 	}
 
+	public function scheduleAfter(string $job, int $runAfter, $argument = null): void {
+		$this->add($job, $argument, $runAfter);
+	}
+
 	/**
 	 * @param IJob|string $job
 	 * @param mixed $argument
 	 */
-	public function remove($job, $argument = null) {
-		if ($job instanceof IJob) {
-			$class = get_class($job);
-		} else {
-			$class = $job;
-		}
+	public function remove($job, $argument = null): void {
+		$class = ($job instanceof IJob) ? get_class($job) : $job;
 
 		$query = $this->connection->getQueryBuilder();
 		$query->delete('jobs')
 			->where($query->expr()->eq('class', $query->createNamedParameter($class)));
 		if (!is_null($argument)) {
 			$argumentJson = json_encode($argument);
-			$query->andWhere($query->expr()->eq('argument_hash', $query->createNamedParameter(md5($argumentJson))));
+			$query->andWhere($query->expr()->eq('argument_hash', $query->createNamedParameter(hash('sha256', $argumentJson))));
 		}
 
 		// Add galera safe delete chunking if using mysql
 		// Stops us hitting wsrep_max_ws_rows when large row counts are deleted
-		if ($this->connection->getDatabasePlatform() instanceof MySQLPlatform) {
+		if ($this->connection->getDatabaseProvider() === IDBConnection::PLATFORM_MYSQL) {
 			// Then use chunked delete
 			$max = IQueryBuilder::MAX_ROW_DELETION;
 
 			$query->setMaxResults($max);
 
 			do {
-				$deleted = $query->execute();
+				$deleted = $query->executeStatement();
 			} while ($deleted === $max);
 		} else {
 			// Dont use chunked delete - let the DB handle the large row count natively
-			$query->execute();
+			$query->executeStatement();
 		}
 	}
 
-	/**
-	 * @param int $id
-	 */
-	protected function removeById($id) {
+	public function removeById(int $id): void {
 		$query = $this->connection->getQueryBuilder();
 		$query->delete('jobs')
 			->where($query->expr()->eq('id', $query->createNamedParameter($id, IQueryBuilder::PARAM_INT)));
-		$query->execute();
+		$query->executeStatement();
 	}
 
 	/**
 	 * check if a job is in the list
 	 *
-	 * @param IJob|string $job
+	 * @param IJob|class-string<IJob> $job
 	 * @param mixed $argument
-	 * @return bool
 	 */
-	public function has($job, $argument) {
-		if ($job instanceof IJob) {
-			$class = get_class($job);
-		} else {
-			$class = $job;
-		}
+	public function has($job, $argument): bool {
+		$class = ($job instanceof IJob) ? get_class($job) : $job;
 		$argument = json_encode($argument);
 
 		$query = $this->connection->getQueryBuilder();
 		$query->select('id')
 			->from('jobs')
 			->where($query->expr()->eq('class', $query->createNamedParameter($class)))
-			->andWhere($query->expr()->eq('argument_hash', $query->createNamedParameter(md5($argument))))
+			->andWhere($query->expr()->eq('argument_hash', $query->createNamedParameter(hash('sha256', $argument))))
 			->setMaxResults(1);
 
-		$result = $query->execute();
+		$result = $query->executeQuery();
 		$row = $result->fetch();
 		$result->closeCursor();
 
-		return (bool) $row;
+		return (bool)$row;
+	}
+
+	public function getJobs($job, ?int $limit, int $offset): array {
+		$iterable = $this->getJobsIterator($job, $limit, $offset);
+		return (is_array($iterable))
+			? $iterable
+			: iterator_to_array($iterable);
 	}
 
 	/**
-	 * get all jobs in the list
-	 *
-	 * @return IJob[]
-	 * @deprecated 9.0.0 - This method is dangerous since it can cause load and
-	 * memory problems when creating too many instances.
+	 * @param IJob|class-string<IJob>|null $job
+	 * @return iterable<IJob> Avoid to store these objects as they may share a Singleton instance. You should instead use these IJobs instances while looping on the iterable.
 	 */
-	public function getAll() {
+	public function getJobsIterator($job, ?int $limit, int $offset): iterable {
 		$query = $this->connection->getQueryBuilder();
 		$query->select('*')
-			->from('jobs');
-		$result = $query->execute();
+			->from('jobs')
+			->setMaxResults($limit)
+			->setFirstResult($offset);
+
+		if ($job !== null) {
+			$class = ($job instanceof IJob) ? get_class($job) : $job;
+			$query->where($query->expr()->eq('class', $query->createNamedParameter($class)));
+		}
+
+		$result = $query->executeQuery();
 
-		$jobs = [];
 		while ($row = $result->fetch()) {
 			$job = $this->buildJob($row);
 			if ($job) {
-				$jobs[] = $job;
+				yield $job;
 			}
 		}
 		$result->closeCursor();
-
-		return $jobs;
 	}
 
 	/**
-	 * get the next job in the list
-	 *
-	 * @param bool $onlyTimeSensitive
-	 * @return IJob|null
+	 * @inheritDoc
 	 */
-	public function getNext(bool $onlyTimeSensitive = false): ?IJob {
+	public function getNext(bool $onlyTimeSensitive = false, ?array $jobClasses = null): ?IJob {
 		$query = $this->connection->getQueryBuilder();
 		$query->select('*')
 			->from('jobs')
@@ -216,29 +185,80 @@ class JobList implements IJobList {
 			$query->andWhere($query->expr()->eq('time_sensitive', $query->createNamedParameter(IJob::TIME_SENSITIVE, IQueryBuilder::PARAM_INT)));
 		}
 
-		$update = $this->connection->getQueryBuilder();
-		$update->update('jobs')
-			->set('reserved_at', $update->createNamedParameter($this->timeFactory->getTime()))
-			->set('last_checked', $update->createNamedParameter($this->timeFactory->getTime()))
-			->where($update->expr()->eq('id', $update->createParameter('jobid')))
-			->andWhere($update->expr()->eq('reserved_at', $update->createParameter('reserved_at')))
-			->andWhere($update->expr()->eq('last_checked', $update->createParameter('last_checked')));
+		if (!empty($jobClasses)) {
+			$orClasses = [];
+			foreach ($jobClasses as $jobClass) {
+				$orClasses[] = $query->expr()->eq('class', $query->createNamedParameter($jobClass, IQueryBuilder::PARAM_STR));
+			}
+			$query->andWhere($query->expr()->orX(...$orClasses));
+		}
 
-		$result = $query->execute();
+		$result = $query->executeQuery();
 		$row = $result->fetch();
 		$result->closeCursor();
 
 		if ($row) {
+			$job = $this->buildJob($row);
+
+			if ($job instanceof IParallelAwareJob && !$job->getAllowParallelRuns() && $this->hasReservedJob(get_class($job))) {
+				if (!isset($this->alreadyVisitedParallelBlocked[get_class($job)])) {
+					$this->alreadyVisitedParallelBlocked[get_class($job)] = $job->getId();
+				} elseif ($this->alreadyVisitedParallelBlocked[get_class($job)] === $job->getId()) {
+					$this->logger->info('Skipped through all jobs and revisited a IParallelAwareJob blocked job again, giving up.', ['app' => 'cron']);
+					return null;
+				}
+				$this->logger->info('Skipping ' . get_class($job) . ' job with ID ' . $job->getId() . ' because another job with the same class is already running', ['app' => 'cron']);
+
+				$update = $this->connection->getQueryBuilder();
+				$update->update('jobs')
+					->set('last_checked', $update->createNamedParameter($this->timeFactory->getTime() + 1))
+					->where($update->expr()->eq('id', $update->createParameter('jobid')));
+				$update->setParameter('jobid', $row['id']);
+				$update->executeStatement();
+
+				return $this->getNext($onlyTimeSensitive, $jobClasses);
+			}
+
+			if ($job !== null && isset($this->alreadyVisitedParallelBlocked[get_class($job)])) {
+				unset($this->alreadyVisitedParallelBlocked[get_class($job)]);
+			}
+
+			if ($job instanceof \OCP\BackgroundJob\TimedJob) {
+				$now = $this->timeFactory->getTime();
+				$nextPossibleRun = $job->getLastRun() + $job->getInterval();
+				if ($now < $nextPossibleRun) {
+					// This job is not ready for execution yet. Set timestamps to the future to avoid
+					// re-checking with every cron run.
+					// To avoid bugs that lead to jobs never executing again, the future timestamp is
+					// capped at two days.
+					$nextCheck = min($nextPossibleRun, $now + 48 * 3600);
+					$updateTimedJob = $this->connection->getQueryBuilder();
+					$updateTimedJob->update('jobs')
+						->set('last_checked', $updateTimedJob->createNamedParameter($nextCheck, IQueryBuilder::PARAM_INT))
+						->where($updateTimedJob->expr()->eq('id', $updateTimedJob->createParameter('jobid')));
+					$updateTimedJob->setParameter('jobid', $row['id']);
+					$updateTimedJob->executeStatement();
+
+					return $this->getNext($onlyTimeSensitive, $jobClasses);
+				}
+			}
+
+			$update = $this->connection->getQueryBuilder();
+			$update->update('jobs')
+				->set('reserved_at', $update->createNamedParameter($this->timeFactory->getTime()))
+				->set('last_checked', $update->createNamedParameter($this->timeFactory->getTime()))
+				->where($update->expr()->eq('id', $update->createParameter('jobid')))
+				->andWhere($update->expr()->eq('reserved_at', $update->createParameter('reserved_at')))
+				->andWhere($update->expr()->eq('last_checked', $update->createParameter('last_checked')));
 			$update->setParameter('jobid', $row['id']);
 			$update->setParameter('reserved_at', $row['reserved_at']);
 			$update->setParameter('last_checked', $row['last_checked']);
-			$count = $update->execute();
+			$count = $update->executeStatement();
 
 			if ($count === 0) {
 				// Background job already executed elsewhere, try again.
-				return $this->getNext($onlyTimeSensitive);
+				return $this->getNext($onlyTimeSensitive, $jobClasses);
 			}
-			$job = $this->buildJob($row);
 
 			if ($job === null) {
 				// set the last_checked to 12h in the future to not check failing jobs all over again
@@ -247,10 +267,10 @@ class JobList implements IJobList {
 					->set('reserved_at', $reset->expr()->literal(0, IQueryBuilder::PARAM_INT))
 					->set('last_checked', $reset->createNamedParameter($this->timeFactory->getTime() + 12 * 3600, IQueryBuilder::PARAM_INT))
 					->where($reset->expr()->eq('id', $reset->createNamedParameter($row['id'], IQueryBuilder::PARAM_INT)));
-				$reset->execute();
+				$reset->executeStatement();
 
 				// Background job from disabled app, try again.
-				return $this->getNext($onlyTimeSensitive);
+				return $this->getNext($onlyTimeSensitive, $jobClasses);
 			}
 
 			return $job;
@@ -260,10 +280,9 @@ class JobList implements IJobList {
 	}
 
 	/**
-	 * @param int $id
-	 * @return IJob|null
+	 * @return ?IJob The job matching the id. Beware that this object may be a singleton and may be modified by the next call to buildJob.
 	 */
-	public function getById($id) {
+	public function getById(int $id): ?IJob {
 		$row = $this->getDetailsById($id);
 
 		if ($row) {
@@ -292,27 +311,33 @@ class JobList implements IJobList {
 	/**
 	 * get the job object from a row in the db
 	 *
-	 * @param array $row
-	 * @return IJob|null
+	 * @param array{class:class-string<IJob>, id:mixed, last_run:mixed, argument:string} $row
+	 * @return ?IJob the next job to run. Beware that this object may be a singleton and may be modified by the next call to buildJob.
 	 */
-	private function buildJob($row) {
+	private function buildJob(array $row): ?IJob {
 		try {
 			try {
 				// Try to load the job as a service
 				/** @var IJob $job */
-				$job = \OC::$server->query($row['class']);
+				$job = \OCP\Server::get($row['class']);
 			} catch (QueryException $e) {
 				if (class_exists($row['class'])) {
 					$class = $row['class'];
 					$job = new $class();
 				} else {
-					// job from disabled app or old version of an app, no need to do anything
+					$this->logger->warning('failed to create instance of background job: ' . $row['class'], ['app' => 'cron', 'exception' => $e]);
+					// Remove job from disabled app or old version of an app
+					$this->removeById($row['id']);
 					return null;
 				}
 			}
 
-			$job->setId((int) $row['id']);
-			$job->setLastRun((int) $row['last_run']);
+			if (!($job instanceof IJob)) {
+				// This most likely means an invalid job was enqueued. We can ignore it.
+				return null;
+			}
+			$job->setId((int)$row['id']);
+			$job->setLastRun((int)$row['last_run']);
 			$job->setArgument(json_decode($row['argument'], true));
 			return $job;
 		} catch (AutoloadNotAllowedException $e) {
@@ -323,33 +348,27 @@ class JobList implements IJobList {
 
 	/**
 	 * set the job that was last ran
-	 *
-	 * @param IJob $job
 	 */
-	public function setLastJob(IJob $job) {
+	public function setLastJob(IJob $job): void {
 		$this->unlockJob($job);
-		$this->config->setAppValue('backgroundjob', 'lastjob', $job->getId());
+		$this->config->setAppValue('backgroundjob', 'lastjob', (string)$job->getId());
 	}
 
 	/**
 	 * Remove the reservation for a job
-	 *
-	 * @param IJob $job
 	 */
-	public function unlockJob(IJob $job) {
+	public function unlockJob(IJob $job): void {
 		$query = $this->connection->getQueryBuilder();
 		$query->update('jobs')
 			->set('reserved_at', $query->expr()->literal(0, IQueryBuilder::PARAM_INT))
 			->where($query->expr()->eq('id', $query->createNamedParameter($job->getId(), IQueryBuilder::PARAM_INT)));
-		$query->execute();
+		$query->executeStatement();
 	}
 
 	/**
 	 * set the lastRun of $job to now
-	 *
-	 * @param IJob $job
 	 */
-	public function setLastRun(IJob $job) {
+	public function setLastRun(IJob $job): void {
 		$query = $this->connection->getQueryBuilder();
 		$query->update('jobs')
 			->set('last_run', $query->createNamedParameter(time(), IQueryBuilder::PARAM_INT))
@@ -360,25 +379,24 @@ class JobList implements IJobList {
 			$query->set('time_sensitive', $query->createNamedParameter(IJob::TIME_INSENSITIVE));
 		}
 
-		$query->execute();
+		$query->executeStatement();
 	}
 
 	/**
-	 * @param IJob $job
-	 * @param $timeTaken
+	 * @param int $timeTaken
 	 */
-	public function setExecutionTime(IJob $job, $timeTaken) {
+	public function setExecutionTime(IJob $job, $timeTaken): void {
 		$query = $this->connection->getQueryBuilder();
 		$query->update('jobs')
 			->set('execution_duration', $query->createNamedParameter($timeTaken, IQueryBuilder::PARAM_INT))
+			->set('reserved_at', $query->createNamedParameter(0, IQueryBuilder::PARAM_INT))
 			->where($query->expr()->eq('id', $query->createNamedParameter($job->getId(), IQueryBuilder::PARAM_INT)));
-		$query->execute();
+		$query->executeStatement();
 	}
 
 	/**
 	 * Reset the $job so it executes on the next trigger
 	 *
-	 * @param IJob $job
 	 * @since 23.0.0
 	 */
 	public function resetBackgroundJob(IJob $job): void {
@@ -389,4 +407,48 @@ class JobList implements IJobList {
 			->where($query->expr()->eq('id', $query->createNamedParameter($job->getId()), IQueryBuilder::PARAM_INT));
 		$query->executeStatement();
 	}
+
+	public function hasReservedJob(?string $className = null): bool {
+		$query = $this->connection->getQueryBuilder();
+		$query->select('*')
+			->from('jobs')
+			->where($query->expr()->gt('reserved_at', $query->createNamedParameter($this->timeFactory->getTime() - 6 * 3600, IQueryBuilder::PARAM_INT)))
+			->setMaxResults(1);
+
+		if ($className !== null) {
+			$query->andWhere($query->expr()->eq('class', $query->createNamedParameter($className)));
+		}
+
+		try {
+			$result = $query->executeQuery();
+			$hasReservedJobs = $result->fetch() !== false;
+			$result->closeCursor();
+			return $hasReservedJobs;
+		} catch (Exception $e) {
+			$this->logger->debug('Querying reserved jobs failed', ['exception' => $e]);
+			return false;
+		}
+	}
+
+	public function countByClass(): array {
+		$query = $this->connection->getQueryBuilder();
+		$query->select('class')
+			->selectAlias($query->func()->count('id'), 'count')
+			->from('jobs')
+			->orderBy('count')
+			->groupBy('class');
+
+		$result = $query->executeQuery();
+
+		$jobs = [];
+
+		while (($row = $result->fetch()) !== false) {
+			/**
+			 * @var array{count:int, class:class-string} $row
+			 */
+			$jobs[] = $row;
+		}
+
+		return $jobs;
+	}
 }
diff --git a/lib/private/BackgroundJob/Legacy/QueuedJob.php b/lib/private/BackgroundJob/Legacy/QueuedJob.php
deleted file mode 100644
index fd001738d4f..00000000000
--- a/lib/private/BackgroundJob/Legacy/QueuedJob.php
+++ /dev/null
@@ -1,38 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Christoph Wurst <christoph@winzerhof-wurst.at>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Robin Appelman <robin@icewind.nl>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program. If not, see <http://www.gnu.org/licenses/>
- *
- */
-namespace OC\BackgroundJob\Legacy;
-
-/**
- * @deprecated internal class, use \OCP\BackgroundJob\QueuedJob
- */
-class QueuedJob extends \OC\BackgroundJob\QueuedJob {
-	public function run($argument) {
-		$class = $argument['klass'];
-		$method = $argument['method'];
-		$parameters = $argument['parameters'];
-		if (is_callable([$class, $method])) {
-			call_user_func([$class, $method], $parameters);
-		}
-	}
-}
diff --git a/lib/private/BackgroundJob/Legacy/RegularJob.php b/lib/private/BackgroundJob/Legacy/RegularJob.php
deleted file mode 100644
index 0f337a35eb0..00000000000
--- a/lib/private/BackgroundJob/Legacy/RegularJob.php
+++ /dev/null
@@ -1,41 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Robin Appelman <robin@icewind.nl>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program. If not, see <http://www.gnu.org/licenses/>
- *
- */
-namespace OC\BackgroundJob\Legacy;
-
-use OCP\AutoloadNotAllowedException;
-
-/**
- * @deprecated internal class, use \OCP\BackgroundJob\QueuedJob
- */
-class RegularJob extends \OC\BackgroundJob\Job {
-	public function run($argument) {
-		try {
-			if (is_callable($argument)) {
-				call_user_func($argument);
-			}
-		} catch (AutoloadNotAllowedException $e) {
-			// job is from a disabled app, ignore
-			return null;
-		}
-	}
-}
diff --git a/lib/private/BackgroundJob/QueuedJob.php b/lib/private/BackgroundJob/QueuedJob.php
deleted file mode 100644
index 28d86481e62..00000000000
--- a/lib/private/BackgroundJob/QueuedJob.php
+++ /dev/null
@@ -1,49 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Christoph Wurst <christoph@winzerhof-wurst.at>
- * @author Lukas Reschke <lukas@statuscode.ch>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Robin Appelman <robin@icewind.nl>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program. If not, see <http://www.gnu.org/licenses/>
- *
- */
-namespace OC\BackgroundJob;
-
-use OCP\ILogger;
-
-/**
- * Class QueuedJob
- *
- * create a background job that is to be executed once
- *
- * @package OC\BackgroundJob
- *
- * @deprecated internal class, use \OCP\BackgroundJob\QueuedJob
- */
-abstract class QueuedJob extends Job {
-	/**
-	 * run the job, then remove it from the joblist
-	 *
-	 * @param JobList $jobList
-	 * @param ILogger|null $logger
-	 */
-	public function execute($jobList, ILogger $logger = null) {
-		$jobList->remove($this, $this->argument);
-		parent::execute($jobList, $logger);
-	}
-}
diff --git a/lib/private/BackgroundJob/TimedJob.php b/lib/private/BackgroundJob/TimedJob.php
deleted file mode 100644
index 0f0951e1aec..00000000000
--- a/lib/private/BackgroundJob/TimedJob.php
+++ /dev/null
@@ -1,63 +0,0 @@
-<?php
-/**
- * @copyright Copyright (c) 2016, ownCloud, Inc.
- *
- * @author Christoph Wurst <christoph@winzerhof-wurst.at>
- * @author Daniel Kesselberg <mail@danielkesselberg.de>
- * @author Lukas Reschke <lukas@statuscode.ch>
- * @author Morris Jobke <hey@morrisjobke.de>
- * @author Robin Appelman <robin@icewind.nl>
- *
- * @license AGPL-3.0
- *
- * This code is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License, version 3,
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU Affero General Public License for more details.
- *
- * You should have received a copy of the GNU Affero General Public License, version 3,
- * along with this program. If not, see <http://www.gnu.org/licenses/>
- *
- */
-namespace OC\BackgroundJob;
-
-use OCP\BackgroundJob\IJobList;
-use OCP\ILogger;
-
-/**
- * Class QueuedJob
- *
- * create a background job that is to be executed at an interval
- *
- * @package OC\BackgroundJob
- *
- * @deprecated internal class, use \OCP\BackgroundJob\TimedJob
- */
-abstract class TimedJob extends Job {
-	protected $interval = 0;
-
-	/**
-	 * set the interval for the job
-	 *
-	 * @param int $interval
-	 */
-	public function setInterval($interval) {
-		$this->interval = $interval;
-	}
-
-	/**
-	 * run the job if
-	 *
-	 * @param IJobList $jobList
-	 * @param ILogger|null $logger
-	 */
-	public function execute($jobList, ILogger $logger = null) {
-		if ((time() - $this->lastRun) > $this->interval) {
-			parent::execute($jobList, $logger);
-		}
-	}
-}