From 638592584582126c93c8db79ccbfdd45b04d2047 Mon Sep 17 00:00:00 2001 From: Dillard Blom Date: Sun, 11 Oct 2026 12:24:00 +0200 Subject: [PATCH] Backup step: write the run only if no other process wrote it since it was loaded --- CHANGELOG.md | 6 ++--- lib/Db/RunMapper.php | 30 ++++++++++++++++++++++ lib/Service/BackupService.php | 47 +++++++++++++++++++---------------- 3 files changed, 58 insertions(+), 25 deletions(-) diff --git a/CHANGELOG.md b/CHANGELOG.md index 98d8812..7a1ba66 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -17,9 +17,9 @@ instead carried by the app description, the git tag, the release, and this file. - A long first backup could end as failed although its snapshot was complete: when its final step took longer than the step's lease (150 s with `occ backup:run`), the background job took the run over, finished it a second time and failed on the snapshot it had already recorded, - overwriting the result. The lease now lasts at least 15 minutes, a step no longer overwrites a - run that another process wrote in the meantime, and recording a snapshot that is already - recorded is no longer an error. + overwriting the result. The lease now lasts at least 15 minutes, a step writes the run only if + no other process wrote it since the step loaded it (in one database statement), and recording + a snapshot that is already recorded is no longer an error. ## [0.9.4-beta.5] - 2026-10-09 diff --git a/lib/Db/RunMapper.php b/lib/Db/RunMapper.php index 9799259..162f4d7 100644 --- a/lib/Db/RunMapper.php +++ b/lib/Db/RunMapper.php @@ -17,6 +17,36 @@ final class RunMapper extends QBMapper { parent::__construct($db, 'ngb_runs', Run::class); } + /** + * Write $run only if it is still running and unchanged since it was loaded (updated_at + * $loadedAt), in one statement: two processes that loaded the same run cannot both write it. + * The new updated_at is always later than $loadedAt, so every write is seen as a change. + * + * @return Run|null the written run, or null when another process wrote it first + */ + public function updateIfUnchanged(Run $run, int $loadedAt): ?Run { + $run->setUpdatedAt(max(time(), $loadedAt + 1)); + $types = $run->getFieldTypes(); + $qb = $this->db->getQueryBuilder(); + $qb->update($this->getTableName()); + foreach (array_keys($run->getUpdatedFields()) as $field) { + if ($field === 'id') { + continue; + } + $value = $run->{'get' . ucfirst($field)}(); + $type = ($types[$field] ?? 'string') === 'integer' ? IQueryBuilder::PARAM_INT : IQueryBuilder::PARAM_STR; + $qb->set($run->propertyToColumn($field), $qb->createNamedParameter($value, $value === null ? IQueryBuilder::PARAM_NULL : $type)); + } + $qb->where($qb->expr()->eq('id', $qb->createNamedParameter($run->getId(), IQueryBuilder::PARAM_INT))) + ->andWhere($qb->expr()->eq('status', $qb->createNamedParameter(Run::RUNNING))) + ->andWhere($qb->expr()->eq('updated_at', $qb->createNamedParameter($loadedAt, IQueryBuilder::PARAM_INT))); + if ($qb->executeStatement() !== 1) { + return null; + } + $run->resetUpdatedFields(); + return $run; + } + public function find(int $id): Run { $qb = $this->db->getQueryBuilder(); $qb->select('*')->from($this->getTableName())->where($qb->expr()->eq('id', $qb->createNamedParameter($id, IQueryBuilder::PARAM_INT))); diff --git a/lib/Service/BackupService.php b/lib/Service/BackupService.php index 0e7a3db..b2ef6ea 100644 --- a/lib/Service/BackupService.php +++ b/lib/Service/BackupService.php @@ -122,6 +122,7 @@ final class BackupService { $this->leases->release($runLease); return $run; } + $loadedAt = null; try { $run = $this->runs->find($run->getId()); // fresh state after acquiring the lock if ($run->getStatus() !== Run::RUNNING || $run->getKind() !== self::KIND_FULL) { @@ -183,23 +184,27 @@ final class BackupService { } $run->setState(json_encode($state, JSON_THROW_ON_ERROR)); $run->setStats(json_encode(['db' => $state['dbStats'] ?? null, 'files' => $state['files']['stats']], JSON_THROW_ON_ERROR)); - $run->setUpdatedAt(time()); - $current = $this->takenOver($run->getId(), $loadedAt); - return $current ?? $this->runs->update($run); + // Another process may have taken the run over after this step's lease expired: then its + // writes stand and this step's are dropped. + return $this->runs->updateIfUnchanged($run, $loadedAt) ?? $this->runs->find($run->getId()); } catch (\Throwable $e) { - // Another process that took the run over (after this step's lease expired) may have - // finished it in the meantime: its result stands, this step's error does not. - $current = isset($loadedAt) ? $this->takenOver($run->getId(), $loadedAt) : null; - if ($current !== null) { - $this->logger->warning('NG Backup run ' . $run->getId() . ': a step that another process had taken over ended with: ' . $e->getMessage()); - return $current; + if ($loadedAt === null) { + // The run could not even be loaded: there is nothing fresh to mark as failed, and + // the caller's copy may be stale. + $this->logger->error('NG Backup run ' . $run->getId() . ': step could not load the run: ' . $e->getMessage(), ['exception' => $e]); + return $run; } - $this->logger->error('NG Backup run ' . $run->getId() . ' failed: ' . $e->getMessage(), ['exception' => $e]); $run->setStatus(Run::FAILED); $run->setError($e->getMessage()); $run->setFinishedAt(time()); - $run->setUpdatedAt(time()); - $run = $this->runs->update($run); + $failed = $this->runs->updateIfUnchanged($run, $loadedAt); + if ($failed === null) { + // Another process that took the run over may have finished it: its result stands. + $this->logger->warning('NG Backup run ' . $run->getId() . ': a step that another process had taken over ended with: ' . $e->getMessage()); + return $this->runs->find($run->getId()); + } + $run = $failed; + $this->logger->error('NG Backup run ' . $run->getId() . ' failed: ' . $e->getMessage(), ['exception' => $e]); try { $this->alerts->runFailed($run, isset($target) ? $target->getName() : '#' . $run->getTargetId()); } catch (\Throwable) { @@ -211,15 +216,6 @@ final class BackupService { } } - /** - * The run as stored, when another process has written it since this step loaded it (updated_at - * $loadedAt); null when it is still this step's to write. - */ - private function takenOver(int $runId, int $loadedAt): ?Run { - $current = $this->runs->find($runId); - return $current->getUpdatedAt() !== $loadedAt || $current->getStatus() !== Run::RUNNING ? $current : null; - } - /** Run to completion in this process (occ, system cron), reporting progress. */ public function runToCompletion(Run $run, ?callable $progress = null, float $stepSeconds = 30): Run { while ($run->getStatus() === Run::RUNNING) { @@ -259,7 +255,14 @@ final class BackupService { $s->setCreatedAt(time()); $s->setFiles($files['stats']['files']); $s->setBytes($files['stats']['bytes']); - $this->snapshots->insert($s); + try { + $this->snapshots->insert($s); + } catch (\OCP\DB\Exception $e) { + // Recorded by another process between the check above and this insert. + if ($e->getReason() !== \OCP\DB\Exception::REASON_UNIQUE_CONSTRAINT_VIOLATION) { + throw $e; + } + } } /** @return list */