166 lines
7.0 KiB
PHP
166 lines
7.0 KiB
PHP
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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\Cache;
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use Psr\Log\LoggerInterface;
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use Symfony\Contracts\Cache\CacheInterface;
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use Symfony\Contracts\Cache\ItemInterface;
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/**
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* LockRegistry is used internally by existing adapters to protect against cache stampede.
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*
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* It does so by wrapping the computation of items in a pool of locks.
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* Foreach each apps, there can be at most 20 concurrent processes that
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* compute items at the same time and only one per cache-key.
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*
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* @author Nicolas Grekas <p@tchwork.com>
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*/
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final class LockRegistry
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{
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private static $openedFiles = [];
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private static $lockedFiles;
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private static $signalingException;
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private static $signalingCallback;
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/**
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* The number of items in this list controls the max number of concurrent processes.
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*/
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private static $files = [
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'AbstractAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'AbstractTagAwareAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'AdapterInterface.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ApcuAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ArrayAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ChainAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'CouchbaseBucketAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'CouchbaseCollectionAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'DoctrineAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'DoctrineDbalAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'FilesystemAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'FilesystemTagAwareAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'MemcachedAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'NullAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ParameterNormalizer.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'PdoAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'PhpArrayAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'PhpFilesAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ProxyAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'Psr16Adapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'RedisAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'RedisTagAwareAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TagAwareAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TagAwareAdapterInterface.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TraceableAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TraceableTagAwareAdapter.php',
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];
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/**
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* Defines a set of existing files that will be used as keys to acquire locks.
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*
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* @return array The previously defined set of files
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*/
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public static function setFiles(array $files): array
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{
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$previousFiles = self::$files;
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self::$files = $files;
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foreach (self::$openedFiles as $file) {
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if ($file) {
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flock($file, \LOCK_UN);
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fclose($file);
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}
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}
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self::$openedFiles = self::$lockedFiles = [];
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return $previousFiles;
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}
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public static function compute(callable $callback, ItemInterface $item, bool &$save, CacheInterface $pool, \Closure $setMetadata = null, LoggerInterface $logger = null)
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{
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if ('\\' === \DIRECTORY_SEPARATOR && null === self::$lockedFiles) {
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// disable locking on Windows by default
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self::$files = self::$lockedFiles = [];
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}
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$key = self::$files ? abs(crc32($item->getKey())) % \count(self::$files) : -1;
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if ($key < 0 || self::$lockedFiles || !$lock = self::open($key)) {
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return $callback($item, $save);
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}
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self::$signalingException ?? self::$signalingException = unserialize("O:9:\"Exception\":1:{s:16:\"\0Exception\0trace\";a:0:{}}");
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self::$signalingCallback ?? self::$signalingCallback = function () { throw self::$signalingException; };
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while (true) {
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try {
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$locked = false;
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// race to get the lock in non-blocking mode
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$locked = flock($lock, \LOCK_EX | \LOCK_NB, $wouldBlock);
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if ($locked || !$wouldBlock) {
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$logger && $logger->info(sprintf('Lock %s, now computing item "{key}"', $locked ? 'acquired' : 'not supported'), ['key' => $item->getKey()]);
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self::$lockedFiles[$key] = true;
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$value = $callback($item, $save);
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if ($save) {
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if ($setMetadata) {
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$setMetadata($item);
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}
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$pool->save($item->set($value));
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$save = false;
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}
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return $value;
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}
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// if we failed the race, retry locking in blocking mode to wait for the winner
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$logger && $logger->info('Item "{key}" is locked, waiting for it to be released', ['key' => $item->getKey()]);
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flock($lock, \LOCK_SH);
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} finally {
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flock($lock, \LOCK_UN);
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unset(self::$lockedFiles[$key]);
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}
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try {
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$value = $pool->get($item->getKey(), self::$signalingCallback, 0);
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$logger && $logger->info('Item "{key}" retrieved after lock was released', ['key' => $item->getKey()]);
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$save = false;
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return $value;
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} catch (\Exception $e) {
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if (self::$signalingException !== $e) {
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throw $e;
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}
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$logger && $logger->info('Item "{key}" not found while lock was released, now retrying', ['key' => $item->getKey()]);
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}
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}
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return null;
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}
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private static function open(int $key)
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{
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if (null !== $h = self::$openedFiles[$key] ?? null) {
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return $h;
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}
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set_error_handler(function () {});
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try {
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$h = fopen(self::$files[$key], 'r+');
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} finally {
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restore_error_handler();
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}
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return self::$openedFiles[$key] = $h ?: @fopen(self::$files[$key], 'r');
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}
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}
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