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feature #30572 [Cache] add integration with Messenger to allow computing cached values in a worker (nicolas-grekas)
This PR was merged into the 5.2-dev branch. Discussion ---------- [Cache] add integration with Messenger to allow computing cached values in a worker | Q | A | ------------- | --- | Branch? | master | Bug fix? | no | New feature? | yes | BC breaks? | no | Deprecations? | no | Tests pass? | yes | Fixed tickets | - | License | MIT | Doc PR | - ~~This PR needs and for now embeds #30334. See 2nd commit.~~ Using the new `CacheInterface` enables probabilistic early expiration by default. This means that from time to time, items are elected as early-expired while they are still fresh ([see Wikipedia](https://en.wikipedia.org/wiki/Cache_stampede#Probabilistic_early_expiration) for details). This PR adds a new `early_expiration_message_bus` option when configuring cache pools. When this option is set, cache pools are configured to send those early-expired items on a Messenger bus, then serve the current value immediately, while the updated value is computed in a worker in the background. `CacheInterface::get($key, $callback)` accepts any callable, but sending any callable on a bus is not possible (e.g. a `Closure` cannot be serialized). To bypass this constraint, this feature works only with callables in the form `[$service, 'publicMethod']`, where `$service` is any public or [reversible service](#30334). This constraint is a serious one: this $service must compute a value when knowing only its key. This means keys should embed enough information for this to happen. I think that's not that hard - and we may find ways to provide additional context in the future. At least the goal is worth it: in theory, this strategy allows achieving a 100% hit ratio even when invalidation-by-expiration is used. There are two things one needs to do to enable this behavior: 1. bind a message bus to a cache pool: ```yaml framework: cache: pools: test.cache: early_expiration_message_bus: messenger.default_bus ``` 2. route EarlyExpirationMessage to a transport: ```yaml framework: messenger: routing: 'Symfony\Component\Cache\Messenger\EarlyExpirationMessage': amqp ``` Commits ------- 6c0911f [Cache] add integration with Messenger to allow computing cached values in a worker
2 parents 11b1429 + 6c0911f commit adedd76

18 files changed

+560
-30
lines changed

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

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@@ -1041,6 +1041,9 @@ private function addCacheSection(ArrayNodeDefinition $rootNode)
10411041
->scalarNode('provider')
10421042
->info('Overwrite the setting from the default provider for this adapter.')
10431043
->end()
1044+
->scalarNode('early_expiration_message_bus')
1045+
->example('"messenger.default_bus" to send early expiration events to the default Messenger bus.')
1046+
->end()
10441047
->scalarNode('clearer')->end()
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->end()
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->end()

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

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@@ -147,6 +147,7 @@
147147
use Symfony\Component\Yaml\Command\LintCommand as BaseYamlLintCommand;
148148
use Symfony\Component\Yaml\Yaml;
149149
use Symfony\Contracts\Cache\CacheInterface;
150+
use Symfony\Contracts\Cache\CallbackInterface;
150151
use Symfony\Contracts\Cache\TagAwareCacheInterface;
151152
use Symfony\Contracts\HttpClient\HttpClientInterface;
152153
use Symfony\Contracts\Service\ResetInterface;
@@ -436,6 +437,8 @@ public function load(array $configs, ContainerBuilder $container)
436437
->addTag('container.env_var_loader');
437438
$container->registerForAutoconfiguration(EnvVarProcessorInterface::class)
438439
->addTag('container.env_var_processor');
440+
$container->registerForAutoconfiguration(CallbackInterface::class)
441+
->addTag('container.reversible');
439442
$container->registerForAutoconfiguration(ServiceLocator::class)
440443
->addTag('container.service_locator');
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$container->registerForAutoconfiguration(ServiceSubscriberInterface::class)

‎src/Symfony/Bundle/FrameworkBundle/Resources/config/cache.php‎

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@@ -25,6 +25,7 @@
2525
use Symfony\Component\Cache\Adapter\RedisTagAwareAdapter;
2626
use Symfony\Component\Cache\Adapter\TagAwareAdapter;
2727
use Symfony\Component\Cache\Marshaller\DefaultMarshaller;
28+
use Symfony\Component\Cache\Messenger\EarlyExpirationHandler;
2829
use Symfony\Component\HttpKernel\CacheClearer\Psr6CacheClearer;
2930
use Symfony\Contracts\Cache\CacheInterface;
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use Symfony\Contracts\Cache\TagAwareCacheInterface;
@@ -212,6 +213,12 @@
212213
null, // use igbinary_serialize() when available
213214
])
214215

216+
->set('cache.early_expiration_handler', EarlyExpirationHandler::class)
217+
->args([
218+
service('reverse_container'),
219+
])
220+
->tag('messenger.message_handler')
221+
215222
->set('cache.default_clearer', Psr6CacheClearer::class)
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->args([
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[],

‎src/Symfony/Bundle/FrameworkBundle/Resources/config/schema/symfony-1.0.xsd‎

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@@ -284,6 +284,7 @@
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<xsd:attribute name="public" type="xsd:boolean" />
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<xsd:attribute name="default-lifetime" type="xsd:integer" />
286286
<xsd:attribute name="provider" type="xsd:string" />
287+
<xsd:attribute name="early-expiration-message-bus" type="xsd:string" />
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<xsd:attribute name="clearer" type="xsd:string" />
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</xsd:complexType>
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‎src/Symfony/Component/Cache/CHANGELOG.md‎

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@@ -1,6 +1,11 @@
11
CHANGELOG
22
=========
33

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5.2.0
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-----
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* added integration with Messenger to allow computing cached values in a worker
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49
5.1.0
510
-----
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‎src/Symfony/Component/Cache/DependencyInjection/CachePoolPass.php‎

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@@ -14,6 +14,7 @@
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use Symfony\Component\Cache\Adapter\AbstractAdapter;
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use Symfony\Component\Cache\Adapter\ArrayAdapter;
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use Symfony\Component\Cache\Adapter\ChainAdapter;
17+
use Symfony\Component\Cache\Messenger\EarlyExpirationDispatcher;
1718
use Symfony\Component\DependencyInjection\ChildDefinition;
1819
use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
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use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -32,15 +33,21 @@ class CachePoolPass implements CompilerPassInterface
3233
private $cachePoolClearerTag;
3334
private $cacheSystemClearerId;
3435
private $cacheSystemClearerTag;
36+
private $reverseContainerId;
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private $reversibleTag;
38+
private $messageHandlerId;
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36-
public function __construct(string $cachePoolTag = 'cache.pool', string $kernelResetTag = 'kernel.reset', string $cacheClearerId = 'cache.global_clearer', string $cachePoolClearerTag = 'cache.pool.clearer', string $cacheSystemClearerId = 'cache.system_clearer', string $cacheSystemClearerTag = 'kernel.cache_clearer')
40+
public function __construct(string $cachePoolTag = 'cache.pool', string $kernelResetTag = 'kernel.reset', string $cacheClearerId = 'cache.global_clearer', string $cachePoolClearerTag = 'cache.pool.clearer', string $cacheSystemClearerId = 'cache.system_clearer', string $cacheSystemClearerTag = 'kernel.cache_clearer', string $reverseContainerId = 'reverse_container', string $reversibleTag = 'container.reversible', string $messageHandlerId = 'cache.early_expiration_handler')
3741
{
3842
$this->cachePoolTag = $cachePoolTag;
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$this->kernelResetTag = $kernelResetTag;
4044
$this->cacheClearerId = $cacheClearerId;
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$this->cachePoolClearerTag = $cachePoolClearerTag;
4246
$this->cacheSystemClearerId = $cacheSystemClearerId;
4347
$this->cacheSystemClearerTag = $cacheSystemClearerTag;
48+
$this->reverseContainerId = $reverseContainerId;
49+
$this->reversibleTag = $reversibleTag;
50+
$this->messageHandlerId = $messageHandlerId;
4451
}
4552

4653
/**
@@ -55,13 +62,15 @@ public function process(ContainerBuilder $container)
5562
$seed .= '.'.$container->getParameter('kernel.container_class');
5663
}
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65+
$needsMessageHandler = false;
5866
$allPools = [];
5967
$clearers = [];
6068
$attributes = [
6169
'provider',
6270
'name',
6371
'namespace',
6472
'default_lifetime',
73+
'early_expiration_message_bus',
6574
'reset',
6675
];
6776
foreach ($container->findTaggedServiceIds($this->cachePoolTag) as $id => $tags) {
@@ -155,13 +164,24 @@ public function process(ContainerBuilder $container)
155164
if ($tags[0][$attr]) {
156165
$pool->addTag($this->kernelResetTag, ['method' => $tags[0][$attr]]);
157166
}
167+
} elseif ('early_expiration_message_bus' === $attr) {
168+
$needsMessageHandler = true;
169+
$pool->addMethodCall('setCallbackWrapper', [(new Definition(EarlyExpirationDispatcher::class))
170+
->addArgument(new Reference($tags[0]['early_expiration_message_bus']))
171+
->addArgument(new Reference($this->reverseContainerId))
172+
->addArgument((new Definition('callable'))
173+
->setFactory([new Reference($id), 'setCallbackWrapper'])
174+
->addArgument(null)
175+
),
176+
]);
177+
$pool->addTag($this->reversibleTag);
158178
} elseif ('namespace' !== $attr || ArrayAdapter::class !== $class) {
159179
$pool->replaceArgument($i++, $tags[0][$attr]);
160180
}
161181
unset($tags[0][$attr]);
162182
}
163183
if (!empty($tags[0])) {
164-
throw new InvalidArgumentException(sprintf('Invalid "%s" tag for service "%s": accepted attributes are "clearer", "provider", "name", "namespace", "default_lifetime" and "reset", found "%s".', $this->cachePoolTag, $id, implode('", "', array_keys($tags[0]))));
184+
throw new InvalidArgumentException(sprintf('Invalid "%s" tag for service "%s": accepted attributes are "clearer", "provider", "name", "namespace", "default_lifetime", "early_expiration_message_bus" and "reset", found "%s".', $this->cachePoolTag, $id, implode('", "', array_keys($tags[0]))));
165185
}
166186

167187
if (null !== $clearer) {
@@ -171,6 +191,10 @@ public function process(ContainerBuilder $container)
171191
$allPools[$name] = new Reference($id, $container::IGNORE_ON_UNINITIALIZED_REFERENCE);
172192
}
173193

194+
if (!$needsMessageHandler) {
195+
$container->removeDefinition($this->messageHandlerId);
196+
}
197+
174198
$notAliasedCacheClearerId = $this->cacheClearerId;
175199
while ($container->hasAlias($this->cacheClearerId)) {
176200
$this->cacheClearerId = (string) $container->getAlias($this->cacheClearerId);

‎src/Symfony/Component/Cache/Messenger/EarlyExpirationDispatcher.php‎

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@@ -0,0 +1,61 @@
1+
<?php
2+
3+
/*
4+
* This file is part of the Symfony package.
5+
*
6+
* (c) Fabien Potencier <fabien@symfony.com>
7+
*
8+
* For the full copyright and license information, please view the LICENSE
9+
* file that was distributed with this source code.
10+
*/
11+
12+
namespace Symfony\Component\Cache\Messenger;
13+
14+
use Psr\Log\LoggerInterface;
15+
use Symfony\Component\Cache\Adapter\AdapterInterface;
16+
use Symfony\Component\Cache\CacheItem;
17+
use Symfony\Component\DependencyInjection\ReverseContainer;
18+
use Symfony\Component\Messenger\MessageBusInterface;
19+
use Symfony\Component\Messenger\Stamp\HandledStamp;
20+
21+
/**
22+
* Sends the computation of cached values to a message bus.
23+
*/
24+
class EarlyExpirationDispatcher
25+
{
26+
private $bus;
27+
private $reverseContainer;
28+
private $callbackWrapper;
29+
30+
public function __construct(MessageBusInterface $bus, ReverseContainer $reverseContainer, callable $callbackWrapper = null)
31+
{
32+
$this->bus = $bus;
33+
$this->reverseContainer = $reverseContainer;
34+
$this->callbackWrapper = $callbackWrapper;
35+
}
36+
37+
public function __invoke(callable $callback, CacheItem $item, bool &$save, AdapterInterface $pool, \Closure $setMetadata, LoggerInterface $logger = null)
38+
{
39+
if (!$item->isHit() || null === $message = EarlyExpirationMessage::create($this->reverseContainer, $callback, $item, $pool)) {
40+
// The item is stale or the callback cannot be reversed: we must compute the value now
41+
$logger && $logger->info('Computing item "{key}" online: '.($item->isHit() ? 'callback cannot be reversed' : 'item is stale'), ['key' => $item->getKey()]);
42+
43+
return null !== $this->callbackWrapper ? ($this->callbackWrapper)($callback, $item, $save, $pool, $setMetadata, $logger) : $callback($item, $save);
44+
}
45+
46+
$envelope = $this->bus->dispatch($message);
47+
48+
if ($logger) {
49+
if ($envelope->last(HandledStamp::class)) {
50+
$logger->info('Item "{key}" was computed online', ['key' => $item->getKey()]);
51+
} else {
52+
$logger->info('Item "{key}" sent for recomputation', ['key' => $item->getKey()]);
53+
}
54+
}
55+
56+
// The item's value is not stale, no need to write it to the backend
57+
$save = false;
58+
59+
return $message->getItem()->get() ?? $item->get();
60+
}
61+
}

‎src/Symfony/Component/Cache/Messenger/EarlyExpirationHandler.php‎

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1+
<?php
2+
3+
/*
4+
* This file is part of the Symfony package.
5+
*
6+
* (c) Fabien Potencier <fabien@symfony.com>
7+
*
8+
* For the full copyright and license information, please view the LICENSE
9+
* file that was distributed with this source code.
10+
*/
11+
12+
namespace Symfony\Component\Cache\Messenger;
13+
14+
use Symfony\Component\Cache\CacheItem;
15+
use Symfony\Component\DependencyInjection\ReverseContainer;
16+
use Symfony\Component\Messenger\Handler\MessageHandlerInterface;
17+
18+
/**
19+
* Computes cached values sent to a message bus.
20+
*/
21+
class EarlyExpirationHandler implements MessageHandlerInterface
22+
{
23+
private $reverseContainer;
24+
private $processedNonces = [];
25+
26+
public function __construct(ReverseContainer $reverseContainer)
27+
{
28+
$this->reverseContainer = $reverseContainer;
29+
}
30+
31+
public function __invoke(EarlyExpirationMessage $message)
32+
{
33+
$item = $message->getItem();
34+
$metadata = $item->getMetadata();
35+
$expiry = $metadata[CacheItem::METADATA_EXPIRY] ?? 0;
36+
$ctime = $metadata[CacheItem::METADATA_CTIME] ?? 0;
37+
38+
if ($expiry && $ctime) {
39+
// skip duplicate or expired messages
40+
41+
$processingNonce = [$expiry, $ctime];
42+
$pool = $message->getPool();
43+
$key = $item->getKey();
44+
45+
if (($this->processedNonces[$pool][$key] ?? null) === $processingNonce) {
46+
return;
47+
}
48+
49+
if (microtime(true) >= $expiry) {
50+
return;
51+
}
52+
53+
$this->processedNonces[$pool] = [$key => $processingNonce] + ($this->processedNonces[$pool] ?? []);
54+
55+
if (\count($this->processedNonces[$pool]) > 100) {
56+
array_pop($this->processedNonces[$pool]);
57+
}
58+
}
59+
60+
static $setMetadata;
61+
62+
$setMetadata = $setMetadata ?? \Closure::bind(
63+
function (CacheItem $item, float $startTime) {
64+
if ($item->expiry > $endTime = microtime(true)) {
65+
$item->newMetadata[CacheItem::METADATA_EXPIRY] = $item->expiry;
66+
$item->newMetadata[CacheItem::METADATA_CTIME] = (int) ceil(1000 * ($endTime - $startTime));
67+
}
68+
},
69+
null,
70+
CacheItem::class
71+
);
72+
73+
$startTime = microtime(true);
74+
$pool = $message->findPool($this->reverseContainer);
75+
$callback = $message->findCallback($this->reverseContainer);
76+
$value = $callback($item);
77+
$setMetadata($item, $startTime);
78+
$pool->save($item->set($value));
79+
}
80+
}

‎src/Symfony/Component/Cache/Messenger/EarlyExpirationMessage.php‎

Lines changed: 97 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,97 @@
1+
<?php
2+
3+
/*
4+
* This file is part of the Symfony package.
5+
*
6+
* (c) Fabien Potencier <fabien@symfony.com>
7+
*
8+
* For the full copyright and license information, please view the LICENSE
9+
* file that was distributed with this source code.
10+
*/
11+
12+
namespace Symfony\Component\Cache\Messenger;
13+
14+
use Symfony\Component\Cache\Adapter\AdapterInterface;
15+
use Symfony\Component\Cache\CacheItem;
16+
use Symfony\Component\DependencyInjection\ReverseContainer;
17+
18+
/**
19+
* Conveys a cached value that needs to be computed.
20+
*/
21+
final class EarlyExpirationMessage
22+
{
23+
private $item;
24+
private $pool;
25+
private $callback;
26+
27+
public static function create(ReverseContainer $reverseContainer, callable $callback, CacheItem $item, AdapterInterface $pool): ?self
28+
{
29+
try {
30+
$item = clone $item;
31+
$item->set(null);
32+
} catch (\Exception $e) {
33+
return null;
34+
}
35+
36+
$pool = $reverseContainer->getId($pool);
37+
38+
if (\is_object($callback)) {
39+
if (null === $id = $reverseContainer->getId($callback)) {
40+
return null;
41+
}
42+
43+
$callback = '@'.$id;
44+
} elseif (!\is_array($callback)) {
45+
$callback = (string) $callback;
46+
} elseif (!\is_object($callback[0])) {
47+
$callback = [(string) $callback[0], (string) $callback[1]];
48+
} else {
49+
if (null === $id = $reverseContainer->getId($callback[0])) {
50+
return null;
51+
}
52+
53+
$callback = ['@'.$id, (string) $callback[1]];
54+
}
55+
56+
return new self($item, $pool, $callback);
57+
}
58+
59+
public function getItem(): CacheItem
60+
{
61+
return $this->item;
62+
}
63+
64+
public function getPool(): string
65+
{
66+
return $this->pool;
67+
}
68+
69+
public function getCallback()
70+
{
71+
return $this->callback;
72+
}
73+
74+
public function findPool(ReverseContainer $reverseContainer): AdapterInterface
75+
{
76+
return $reverseContainer->getService($this->pool);
77+
}
78+
79+
public function findCallback(ReverseContainer $reverseContainer): callable
80+
{
81+
if (\is_string($callback = $this->callback)) {
82+
return '@' === $callback[0] ? $reverseContainer->getService(substr($callback, 1)) : $callback;
83+
}
84+
if ('@' === $callback[0][0]) {
85+
$callback[0] = $reverseContainer->getService(substr($callback[0], 1));
86+
}
87+
88+
return $callback;
89+
}
90+
91+
private function __construct(CacheItem $item, string $pool, $callback)
92+
{
93+
$this->item = $item;
94+
$this->pool = $pool;
95+
$this->callback = $callback;
96+
}
97+
}

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