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[Messenger] return empty envelopes when RetryableException occurs #32979

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Merged
merged 1 commit into from
Sep 27, 2019
Merged

[Messenger] return empty envelopes when RetryableException occurs #32979

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23 changes: 23 additions & 0 deletions src/Symfony/Component/Messenger/Tests/Transport/Doctrine/DoctrineReceiverTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -11,9 +11,12 @@

namespace Symfony\Component\Messenger\Tests\Transport\Doctrine;

use Doctrine\DBAL\Driver\PDOException;
use Doctrine\DBAL\Exception\DeadlockException;
use PHPUnit\Framework\TestCase;
use Symfony\Component\Messenger\Envelope;
use Symfony\Component\Messenger\Exception\MessageDecodingFailedException;
use Symfony\Component\Messenger\Exception\TransportException;
use Symfony\Component\Messenger\Stamp\TransportMessageIdStamp;
use Symfony\Component\Messenger\Tests\Fixtures\DummyMessage;
use Symfony\Component\Messenger\Transport\Doctrine\Connection;
Expand Down Expand Up @@ -68,6 +71,26 @@ public function testItRejectTheMessageIfThereIsAMessageDecodingFailedException()
$receiver->get();
}

public function testOccursRetryableExceptionFromConnection()
{
$serializer = $this->createSerializer();
$connection = $this->createMock(Connection::class);
$driverException = new PDOException(new \PDOException('Deadlock', 40001));
$connection->method('get')->willThrowException(new DeadlockException('Deadlock', $driverException));
$receiver = new DoctrineReceiver($connection, $serializer);
$this->assertSame([], $receiver->get());
$this->assertSame([], $receiver->get());
try {
$receiver->get();
} catch (TransportException $exception) {
// skip, and retry
}
$this->assertSame([], $receiver->get());
$this->assertSame([], $receiver->get());
$this->expectException(TransportException::class);
$receiver->get();
}

public function testAll()
{
$serializer = $this->createSerializer();
Expand Down
14 changes: 14 additions & 0 deletions src/Symfony/Component/Messenger/Transport/Doctrine/DoctrineReceiver.php
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Expand Up @@ -12,6 +12,7 @@
namespace Symfony\Component\Messenger\Transport\Doctrine;

use Doctrine\DBAL\DBALException;
use Doctrine\DBAL\Exception\RetryableException;
use Symfony\Component\Messenger\Envelope;
use Symfony\Component\Messenger\Exception\LogicException;
use Symfony\Component\Messenger\Exception\MessageDecodingFailedException;
Expand All @@ -30,6 +31,8 @@
*/
class DoctrineReceiver implements ReceiverInterface, MessageCountAwareInterface, ListableReceiverInterface
{
private const MAX_RETRIES = 3;
private $retryingSafetyCounter = 0;
private $connection;
private $serializer;

Expand All @@ -46,6 +49,17 @@ public function get(): iterable
{
try {
$doctrineEnvelope = $this->connection->get();
$this->retryingSafetyCounter = 0; // reset counter
} catch (RetryableException $exception) {
// Do nothing when RetryableException occurs less than "MAX_RETRIES"
// as it will likely be resolved on the next call to get()
// Problem with concurrent consumers and database deadlocks
if (++$this->retryingSafetyCounter >= self::MAX_RETRIES) {
$this->retryingSafetyCounter = 0; // reset counter
throw new TransportException($exception->getMessage(), 0, $exception);
}

return [];
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Wouldn't it be better to retry "internally" (i.e. return $this->get()) instead of returning this empty array? Otherwise, in the event of using multiple transports, the worker might start consuming lower priority messages, which would make no sense. Similar with whatever might decorate this receiver... it would "see" an empty array while actually, it was an error.

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Does not seem better to me. This way we can use the delay that is added after the get which is what we want with a deadlock/timeout problem.

} catch (DBALException $exception) {
throw new TransportException($exception->getMessage(), 0, $exception);
}
Expand Down
2 changes: 1 addition & 1 deletion src/Symfony/Component/Messenger/composer.json
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Expand Up @@ -20,7 +20,7 @@
"psr/log": "~1.0"
},
"require-dev": {
"doctrine/dbal": "^2.5",
"doctrine/dbal": "^2.6",
"psr/cache": "~1.0",
"symfony/console": "~3.4|~4.0",
"symfony/debug": "~4.1",
Expand Down