8000 [Cache] Prevent stampede at warmup using apcu_entry() for locking by nicolas-grekas · Pull Request #27028 · symfony/symfony · GitHub
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[Cache] Prevent stampede at warmup using apcu_entry() for locking #27028

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[Cache] Prevent stampede at warmup using apcu_entry() for locking #27028

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8 changes: 8 additions & 0 deletions src/Symfony/Component/Cache/Adapter/AbstractAdapter.php
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Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,14 @@ public static function createConnection($dsn, array $options = array())
throw new InvalidArgumentException(sprintf('Unsupported DSN: %s.', $dsn));
}

/**
* {@inheritdoc}
*/
public function get(string $key, callable $callback, float $beta = null)
{
return $this->doGet($this, $key, $callback, $beta ?? 1.0, '' !== $this->namespace ? $this->getId($key) : null);
}

/**
* {@inheritdoc}
*/
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2 changes: 1 addition & 1 deletion src/Symfony/Component/Cache/Adapter/ProxyAdapter.php
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Expand Up @@ -94,7 +94,7 @@ function (CacheItemInterface $innerItem, array $item) {
public function get(string $key, callable $callback, float $beta = null)
{
if (!$this->pool instanceof CacheInterface) {
return $this->doGet($this, $key, $callback, $beta ?? 1.0);
return $this->doGet($this, $key, $callback, $beta ?? 1.0, $this->namespaceLen ? $this->getId($key) : null);
}

return $this->pool->get($this->getId($key), function ($innerItem) use ($key, $callback) {
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24 changes: 24 additions & 0 deletions src/Symfony/Component/Cache/Adapter/TagAwareAdapter.php
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Expand Up @@ -35,6 +35,7 @@ class TagAwareAdapter implements CacheInterface, TagAwareAdapterInterface, Prune
private $setCacheItemTags;
private $getTagsByKey;
private $invalidateTags;
private $getId;
private $tags;
private $knownTagVersions = array();
private $knownTagVersionsTtl;
Expand Down Expand Up @@ -105,6 +106,13 @@ function (AdapterInterface $tagsAdapter, array $tags) {
null,
CacheItem::class
);
$this->getId = \Closure::bind(
function (AbstractAdapter $pool, $key) {
return $pool->getId($key);
},
null,
AbstractAdapter::class
);
}

/**
Expand Down Expand Up @@ -150,6 +158,22 @@ public function invalidateTags(array $tags)
return $ok;
}

/**
* {@inheritdoc}
*/
public function get(string $key, callable $callback, float $beta = null)
{
if ($this->pool instanceof AbstractAdapter) {
$id = ($this->getId)($this->pool, $key);
} elseif ($this->pool instanceof ProxyAdapter) {
$id = ((array) $this->pool)["\0Symfony\\Component\\Cache\\Adapter\\ProxyAdapter\0namespace"].$key;
} else {
$id = null;
}

return $this->doGet($this, $key, $callback, $beta ?? 1.0, $id !== $key ? $id : null);
}

/**
* {@inheritdoc}
*/
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1 change: 1 addition & 0 deletions src/Symfony/Component/Cache/CHANGELOG.md
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Expand Up @@ -5,6 +5,7 @@ CHANGELOG
-----

* added `CacheInterface`, which provides stampede protection via probabilistic early expiration and should become the preferred way to use a cache
* added warmup-time stampede protection using `apcu_entry()` for locking when available
* added sub-second expiry accuracy for backends that support it
* throw `LogicException` when `CacheItem::tag()` is called on an item comin F8E5 g from a non tag-aware pool
* deprecated `CacheItem::getPreviousTags()`, use `CacheItem::getMetadata()` instead
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25 changes: 23 additions & 2 deletions src/Symfony/Component/Cache/Traits/GetTrait.php
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Expand Up @@ -34,7 +34,7 @@ public function get(string $key, callable $callback, float $beta = null)
return $this->doGet($this, $key, $callback, $beta ?? 1.0);
}

private function doGet(CacheItemPoolInterface $pool, string $key, callable $callback, float $beta)
private function doGet(CacheItemPoolInterface $pool, string $key, callable $callback, float $beta, string $lockId = null)
{
$t = 0;
$item = $pool->getItem($key);
Expand Down Expand Up @@ -64,6 +64,7 @@ private function doGet(CacheItemPoolInterface $pool, string $key, callable $call
}

static $save = null;
static $useApcu = null;

if (null === $save) {
$save = \Closure::bind(
Expand All @@ -81,6 +82,26 @@ function (CacheItemPoolInterface $pool, CacheItemInterface $item, $value, float
);
}

return $save($pool, $item, $callback($item), $t);
if (null === $lockId || !$useApcu = $useApcu ?? \function_exists('apcu_entry') && ini_get('apc.enabled') && ('cli' !== \PHP_SAPI || ini_get('apc.enable_cli'))) {
return $save($pool, $item, $callback($item), $t);
}

$t = $t ?: microtime(true);
$lockId = ':'.$lockId;
$isHit = true;
$value = apcu_entry($lockId, function () use ($callback, $item, &$isHit) {
$isHit = false;

return $callback($item);
}, 2);

if (!$isHit) {
$save($pool, $item, $value, $t);
// give some time to concurrent processes to get the value from APCu
usleep(min(300000, (microtime(true) - $t) * 150000));
apcu_delete($lockId);
}

return $value;
}
}
0