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jderussejderusse
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Add jitter to RetryBackof
1 parent ca220a1 commit ace7314

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4 files changed

+37
-6
lines changed

4 files changed

+37
-6
lines changed

‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1641,8 +1641,8 @@ private function addHttpClientRetrySection()
16411641
->addDefaultsIfNotSet()
16421642
->beforeNormalization()
16431643
->always(function ($v) {
1644-
if (isset($v['backoff_service']) && (isset($v['delay']) || isset($v['multiplier']) || isset($v['max_delay']))) {
1645-
throw new \InvalidArgumentException('The "backoff_service" option cannot be used along with the "delay", "multiplier" or "max_delay" options.');
1644+
if (isset($v['backoff_service']) && (isset($v['delay']) || isset($v['multiplier']) || isset($v['max_delay']) || isset($v['jitter']))) {
1645+
throw new \InvalidArgumentException('The "backoff_service" option cannot be used along with the "delay", "multiplier", "max_delay" or "jitter" options.');
16461646
}
16471647
if (isset($v['decider_service']) && (isset($v['http_codes']))) {
16481648
throw new \InvalidArgumentException('The "decider_service" option cannot be used along with the "http_codes" options.');
@@ -1670,6 +1670,7 @@ private function addHttpClientRetrySection()
16701670
->integerNode('delay')->defaultValue(1000)->min(0)->info('Time in ms to delay (or the initial value when multiplier is used)')->end()
16711671
->floatNode('multiplier')->defaultValue(2)->min(1)->info('If greater than 1, delay will grow exponentially for each retry: (delay * (multiple ^ retries))')->end()
16721672
->integerNode('max_delay')->defaultValue(0)->min(0)->info('Max time in ms that a retry should ever be delayed (0 = infinite)')->end()
1673+
->floatNode('jitter')->defaultValue(0.1)->min(0)->max(1)->info('Randomness in percent (between 0 and 1)) to apply to the delay')->end()
16731674
->end()
16741675
;
16751676
}

‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2075,7 +2075,8 @@ private function registerHttpClientRetry(array $retryOptions, string $name, Cont
20752075
$retryDefinition
20762076
->replaceArgument(0, $retryOptions['delay'])
20772077
->replaceArgument(1, $retryOptions['multiplier'])
2078-
->replaceArgument(2, $retryOptions['max_delay']);
2078+
->replaceArgument(2, $retryOptions['max_delay'])
2079+
->replaceArgument(3, $retryOptions['jitter']);
20792080
$container->setDefinition($retryServiceId, $retryDefinition);
20802081

20812082
$backoffReference = new Reference($retryServiceId);

‎src/Symfony/Component/HttpClient/Retry/ExponentialBackOff.php

Lines changed: 13 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -17,7 +17,7 @@
1717
/**
1818
* A retry backOff with a constant or exponential retry delay.
1919
*
20-
* For example, if $delayMilliseconds=10000 & $multiplier=1 (default),
20+
* For example, if $delayMilliseconds=10000 & $multiplier=1,
2121
* each retry will wait exactly 10 seconds.
2222
*
2323
* But if $delayMilliseconds=10000 & $multiplier=2:
@@ -33,13 +33,15 @@ final class ExponentialBackOff implements RetryBackOffInterface
3333
private $delayMilliseconds;
3434
private $multiplier;
3535
private $maxDelayMilliseconds;
36+
private $jitter;
3637

3738
/**
3839
* @param int $delayMilliseconds Amount of time to delay (or the initial value when multiplier is used)
3940
* @param float $multiplier Multiplier to apply to the delay each time a retry occurs
4041
* @param int $maxDelayMilliseconds Maximum delay to allow (0 means no maximum)
42+
* @param float $jitter Probability of randomness int delay (0 = none, 1 = 100% random)
4143
*/
42-
public function __construct(int $delayMilliseconds = 1000, float $multiplier = 2.0, int $maxDelayMilliseconds = 0)
44+
public function __construct(int $delayMilliseconds = 1000, float $multiplier = 2.0, int $maxDelayMilliseconds = 0, float $jitter = 0.1)
4345
{
4446
if ($delayMilliseconds < 0) {
4547
throw new InvalidArgumentException(sprintf('Delay must be greater than or equal to zero: "%s" given.', $delayMilliseconds));
@@ -55,11 +57,20 @@ public function __construct(int $delayMilliseconds = 1000, float $multiplier = 2
5557
throw new InvalidArgumentException(sprintf('Max delay must be greater than or equal to zero: "%s" given.', $maxDelayMilliseconds));
5658
}
5759
$this->maxDelayMilliseconds = $maxDelayMilliseconds;
60+
61+
if ($jitter < 0 || $jitter > 1) {
62+
throw new InvalidArgumentException(sprintf('Jitter must be between 0 and 1: "%s" given.', $jitter));
63+
}
64+
$this->jitter = $jitter;
5865
}
5966

6067
public function getDelay(int $retryCount, string $requestMethod, string $requestUrl, array $requestOptions, int $responseStatusCode, array $responseHeaders, ?string $responseContent, ?TransportExceptionInterface $exception): int
6168
{
6269
$delay = $this->delayMilliseconds * $this->multiplier ** $retryCount;
70+
if ($this->jitter > 0) {
71+
$randomness = $delay * $this->jitter;
72+
$delay = $delay + random_int(-$randomness, +$randomness);
73+
}
6374

6475
if ($delay > $this->maxDelayMilliseconds && 0 !== $this->maxDelayMilliseconds) {
6576
return $this->maxDelayMilliseconds;

‎src/Symfony/Component/HttpClient/Tests/Retry/ExponentialBackOffTest.php

Lines changed: 19 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -21,7 +21,7 @@ class ExponentialBackOffTest extends TestCase
2121
*/
2222
public function testGetDelay(int $delay, int $multiplier, int $maxDelay, int $previousRetries, int $expectedDelay)
2323
{
24-
$backOff = new ExponentialBackOff($delay, $multiplier, $maxDelay);
24+
$backOff = new ExponentialBackOff($delay, $multiplier, $maxDelay, 0);
2525

2626
self::assertSame($expectedDelay, $backOff->getDelay($previousRetries, 'GET', 'http://example.com/', [], 200, [], null, null));
2727
}
@@ -50,4 +50,22 @@ public function provideDelay(): iterable
5050
yield [0, 2, 10000, 0, 0];
5151
yield [0, 2, 10000, 1, 0];
5252
}
53+
54+
public function testJitter()
55+
{
56+
$backOff = new ExponentialBackOff(1000, 1, 0, 1);
57+
$belowHalf = 0;
58+
$aboveHalf = 0;
59+
for ($i = 0; $i < 20; ++$i) {
60+
$delay = $backOff->getDelay(0, 'GET', 'http://example.com/', [], 200, [], null, null);
61+
if ($delay < 500) {
62+
++$belowHalf;
63+
} elseif ($delay > 1500) {
64+
++$aboveHalf;
65+
}
66+
}
67+
68+
$this->assertGreaterThanOrEqual(1, $belowHalf);
69+
$this->assertGreaterThanOrEqual(1, $aboveHalf);
70+
}
5371
}

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