feat: implement periodic full sync job to repair cache inconsistencies

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

lib/BackgroundJob/SyncRepairJob.php

@@ -0,0 +1,90 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\BackgroundJob;
+
+use OCA\Mail\Db\MailboxMapper;
+use OCA\Mail\Events\SynchronizationEvent;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Service\Sync\SyncService;
+use OCP\AppFramework\Db\DoesNotExistException;
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\BackgroundJob\IJobList;
+use OCP\BackgroundJob\TimedJob;
+use OCP\EventDispatcher\IEventDispatcher;
+use OCP\IUserManager;
+use Psr\Log\LoggerInterface;
+
+class SyncRepairJob extends TimedJob {
+	public function __construct(
+		ITimeFactory $time,
+		private SyncService $syncService,
+		private AccountService $accountService,
+		private IUserManager $userManager,
+		private MailboxMapper $mailboxMapper,
+		private IJobList $jobList,
+		private LoggerInterface $logger,
+		private IEventDispatcher $dispatcher,
+	) {
+		parent::__construct($time);
+
+		$this->setInterval(3600 * 24 * 7);
+		$this->setTimeSensitivity(self::TIME_INSENSITIVE);
+	}
+
+	protected function run($argument): void {
+		$accountId = (int)$argument['accountId'];
+
+		try {
+			$account = $this->accountService->findById($accountId);
+		} catch (DoesNotExistException $e) {
+			$this->logger->debug('Could not find account <' . $accountId . '> removing from jobs');
+			$this->jobList->remove(self::class, $argument);
+			return;
+		}
+
+		if(!$account->getMailAccount()->canAuthenticateImap()) {
+			$this->logger->debug('No authentication on IMAP possible, skipping background sync job');
+			return;
+		}
+
+		$user = $this->userManager->get($account->getUserId());
+		if ($user === null || !$user->isEnabled()) {
+			$this->logger->debug(sprintf(
+				'Account %d of user %s could not be found or was disabled, skipping background sync',
+				$account->getId(),
+				$account->getUserId()
+			));
+			return;
+		}
+
+		$rebuildThreads = false;
+		$trashMailboxId = $account->getMailAccount()->getTrashMailboxId();
+		$snoozeMailboxId = $account->getMailAccount()->getSnoozeMailboxId();
+		$sentMailboxId = $account->getMailAccount()->getSentMailboxId();
+		$junkMailboxId = $account->getMailAccount()->getJunkMailboxId();
+		foreach ($this->mailboxMapper->findAll($account) as $mailbox) {
+			$isTrash = $trashMailboxId === $mailbox->getId();
+			$isSnooze = $snoozeMailboxId === $mailbox->getId();
+			$isSent = $sentMailboxId === $mailbox->getId();
+			$isJunk = $junkMailboxId === $mailbox->getId();
+			if ($isTrash || $isSnooze || $isSent || $isJunk) {
+				continue;
+			}
+
+			if ($this->syncService->repairSync($account, $mailbox) > 0) {
+				$rebuildThreads = true;
+			}
+		}
+
+		$this->dispatcher->dispatchTyped(
+			new SynchronizationEvent($account, $this->logger, $rebuildThreads),
+		);
+	}
+}

lib/Controller/MailboxesController.php

@@ -23,6 +23,7 @@
 use OCA\Mail\Service\Sync\SyncService;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\Attribute\NoAdminRequired;
 use OCP\AppFramework\Http\Attribute\OpenAPI;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\IRequest;
@@ -286,4 +287,17 @@ public function clearMailbox(int $id): JSONResponse {
 		$this->mailManager->clearMailbox($account, $mailbox);
 		return new JSONResponse();
 	}
+
+	/**
+	 * Delete all vanished mails that are still cached.
+	 */
+	#[TrapError]
+	#[NoAdminRequired]
+	public function repair(int $id): JSONResponse {
+		$mailbox = $this->mailManager->getMailbox($this->currentUserId, $id);
+		$account = $this->accountService->find($this->currentUserId, $mailbox->getAccountId());
+
+		$this->syncService->repairSync($account, $mailbox);
+		return new JsonResponse();
+	}
 }

lib/IMAP/IMAPClientFactory.php

@@ -121,18 +121,6 @@ public function getClient(Account $account, bool $useCache = true): Horde_Imap_C
 					$this->cacheFactory->createDistributed(md5((string)$account->getId())),
 				),
 			];
-		} else {
-			// WARNING: This is very dangerous! We **will** miss changes when using QRESYNC without
-			//          actually persisting changes to the cache. Especially vanished messages will
-			//          be missed.
-			/**
-			 * If we don't use a cache we use a null cache to trick Horde into
-			 * using QRESYNC/CONDSTORE if they are available
-			 * @see \Horde_Imap_Client_Socket::_loginTasks
-			 */
-			$params['cache'] = [
-				'backend' => new Horde_Imap_Client_Cache_Backend_Null(),
-			];
 		}
 		if ($this->config->getSystemValue('debug', false)) {
 			$params['debug'] = $this->config->getSystemValue('datadirectory') . '/horde_imap.log';

lib/Migration/FixBackgroundJobs.php

@@ -11,6 +11,7 @@
 use OCA\Mail\BackgroundJob\PreviewEnhancementProcessingJob;
 use OCA\Mail\BackgroundJob\QuotaJob;
 use OCA\Mail\BackgroundJob\SyncJob;
+use OCA\Mail\BackgroundJob\SyncRepairJob;
 use OCA\Mail\BackgroundJob\TrainImportanceClassifierJob;
 use OCA\Mail\Db\MailAccount;
 use OCA\Mail\Db\MailAccountMapper;
@@ -43,6 +44,7 @@ public function run(IOutput $output) {
 		$output->startProgress(count($accounts));
 		foreach ($accounts as $account) {
 			$this->jobList->add(SyncJob::class, ['accountId' => $account->getId()]);
+			$this->jobList->add(SyncRepairJob::class, ['accountId' => $account->getId()]);
 			$this->jobList->add(TrainImportanceClassifierJob::class, ['accountId' => $account->getId()]);
 			$this->jobList->add(PreviewEnhancementProcessingJob::class, ['accountId' => $account->getId()]);
 			$this->jobList->add(QuotaJob::class, ['accountId' => $account->getId()]);

lib/Service/Sync/ImapToDbSynchronizer.php

@@ -12,6 +12,7 @@
 use Horde_Imap_Client;
 use Horde_Imap_Client_Base;
 use Horde_Imap_Client_Exception;
+use Horde_Imap_Client_Ids;
 use OCA\Mail\Account;
 use OCA\Mail\Contracts\IMailManager;
 use OCA\Mail\Db\Mailbox;
@@ -42,7 +43,7 @@
 
 class ImapToDbSynchronizer {
 	/** @var int */
-	public const MAX_NEW_MESSAGES = 5000;
+	public const MAX_NEW_MESSAGES = 5000000;
 
 	/** @var DatabaseMessageMapper */
 	private $dbMapper;
@@ -485,4 +486,53 @@ private function runPartialSync(
 
 		return $newOrVanished;
 	}
+
+	/**
+	 * Run a (rather costly) sync to delete cached messages which are not present on IMAP anymore.
+	 *
+	 * @return int Number of detected vanished phantom messages
+	 *
+	 * @throws MailboxLockedException
+	 * @throws ServiceException
+	 */
+	public function repairSync(
+		Account $account,
+		Mailbox $mailbox,
+		LoggerInterface  $logger,
+	): int {
+		$this->mailboxMapper->lockForVanishedSync($mailbox);
+
+		$perf = $this->performanceLogger->startWithLogger(
+			'Repair sync for ' . $account->getId() . ':' . $mailbox->getName(),
+			$logger,
+		);
+
+		// Need to use a client without a cache here (to disable QRESYNC entirely)
+		$client = $this->clientFactory->getClient($account, false);
+		try {
+			$knownUids = $this->dbMapper->findAllUids($mailbox);
+			$hordeMailbox = new \Horde_Imap_Client_Mailbox($mailbox->getName());
+			$phantomVanishedUids = $client->vanished($hordeMailbox, 0, [
+				'ids' => new Horde_Imap_Client_Ids($knownUids),
+			]);
+			if (count($phantomVanishedUids) > 0) {
+				$this->dbMapper->deleteByUid($mailbox, ...$phantomVanishedUids);
+			}
+		} catch (Throwable $e) {
+			$message = sprintf(
+				'Repair sync failed for %d:%s: %s',
+				$account->getId(),
+				$mailbox->getName(),
+				$e->getMessage(),
+			);
+			throw new ServiceException($message, 0, $e);
+		} finally {
+			$this->mailboxMapper->unlockFromVanishedSync($mailbox);
+			$client->logout();
+		}
+
+		$perf->end();
+
+		return count($phantomVanishedUids);
+	}
 }