Truncate failure_message so a large failure cannot crash the worker

src/Command/WorkerCommand.php

@@ -122,8 +122,7 @@ public function execute(Arguments $args, ConsoleIo $io) {
 			return $this->clean($io, (bool)$args->getOption('force'));
 		}
 
-		/** @phpstan-ignore-next-line */
-		return $this->$action($io, $pid);
+		return (int)$this->$action($io, $pid);
 	}
 
 	/**

src/Model/Table/QueuedJobsTable.php

@@ -76,6 +76,16 @@ class QueuedJobsTable extends Table {
 	 */
 	public const DAY = 86400;
 
+	/**
+	 * Maximum byte length persisted to the `failure_message` / `output` TEXT
+	 * columns. A larger value is byte-truncated before save so recording a big
+	 * failure (e.g. a database error that echoes a huge query) can never overflow
+	 * the column and crash the worker while it is recording the failure.
+	 *
+	 * @var int
+	 */
+	public const FAILURE_MESSAGE_MAX_LENGTH = 65535;
+
 	/**
 	 * Terminal `status` value stamped on a job that has exhausted all of its
 	 * retries. Distinguishes a permanently-failed job (which will never run
@@ -768,6 +778,13 @@ public function markJobDone(QueuedJob $job, ?string $output = null): bool {
 	 * @return bool Success
 	 */
 	public function markJobFailed(QueuedJob $job, ?string $failureMessage = null, ?string $output = null): bool {
+		if ($failureMessage !== null) {
+			$failureMessage = mb_strcut($failureMessage, 0, static::FAILURE_MESSAGE_MAX_LENGTH);
+		}
+		if ($output !== null) {
+			$output = mb_strcut($output, 0, static::FAILURE_MESSAGE_MAX_LENGTH);
+		}
+
 		$fields = [
 			'failure_message' => $failureMessage,
 			'memory' => Memory::usage(),

tests/TestCase/Model/Table/QueuedJobsTableTest.php

@@ -133,6 +133,23 @@ public function testMarkJobFailed() {
 		$this->assertTrue($this->QueuedJobs->markJobFailed($job));
 	}
 
+	/**
+	 * A failure message larger than the TEXT column must be truncated instead of
+	 * overflowing the column and throwing while recording the failure.
+	 *
+	 * @return void
+	 */
+	public function testMarkJobFailedTruncatesOversizedMessage() {
+		$job = $this->QueuedJobs->createJob('Foo', ['test' => 'data']);
+		$oversized = str_repeat('x', QueuedJobsTable::FAILURE_MESSAGE_MAX_LENGTH + 5000);
+
+		$this->assertTrue($this->QueuedJobs->markJobFailed($job, $oversized));
+
+		$stored = $this->QueuedJobs->get($job->id);
+		$this->assertNotNull($stored->failure_message);
+		$this->assertLessThanOrEqual(QueuedJobsTable::FAILURE_MESSAGE_MAX_LENGTH, strlen((string)$stored->failure_message));
+	}
+
 	/**
 	 * @return void
 	 */