FM / Cache

/usr/share/php/Symfony/Component/Cache

Name	Size	Mode	Actions
Adapter/	-	0755	rm
DataCollector/	-	0755	rm
DependencyInjection/	-	0755	rm
Exception/	-	0755	rm
Marshaller/	-	0755	rm
Messenger/	-	0755	rm
Traits/	-	0755	rm
autoload.php	7284	0644	edit dl rm
CacheItem.php	5348	0644	edit dl rm
DoctrineProvider.php	2468	0644	edit dl rm
LockRegistry.php	7110	0644	edit dl rm
PruneableInterface.php	485	0644	edit dl rm
Psr16Cache.php	8699	0644	edit dl rm
ResettableInterface.php	418	0644	edit dl rm

Edit: /usr/share/php/Symfony/Component/Cache/LockRegistry.php (7110B)

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Cache;

use Psr\Log\LoggerInterface;
use Symfony\Contracts\Cache\CacheInterface;
use Symfony\Contracts\Cache\ItemInterface;

/**
 * LockRegistry is used internally by existing adapters to protect against cache stampede.
 *
 * It does so by wrapping the computation of items in a pool of locks.
 * Foreach each apps, there can be at most 20 concurrent processes that
 * compute items at the same time and only one per cache-key.
 *
 * @author Nicolas Grekas <p@tchwork.com>
 */
final class LockRegistry
{
    private static $openedFiles = [];
    private static $lockedFiles;

/**
     * The number of items in this list controls the max number of concurrent processes.
     */
    private static $files = [
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'AbstractAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'AbstractTagAwareAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'AdapterInterface.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ApcuAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ArrayAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ChainAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'CouchbaseBucketAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'CouchbaseCollectionAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'DoctrineAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'DoctrineDbalAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'FilesystemAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'FilesystemTagAwareAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'MemcachedAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'NullAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ParameterNormalizer.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'PdoAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'PhpArrayAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'PhpFilesAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'ProxyAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'Psr16Adapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'RedisAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'RedisTagAwareAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TagAwareAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TagAwareAdapterInterface.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TraceableAdapter.php',
        __DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'TraceableTagAwareAdapter.php',
    ];

/**
     * Defines a set of existing files that will be used as keys to acquire locks.
     *
     * @return array The previously defined set of files
     */
    public static function setFiles(array $files): array
    {
        $previousFiles = self::$files;
        self::$files = $files;

foreach (self::$openedFiles as $file) {
            if ($file) {
                flock($file, \LOCK_UN);
                fclose($file);
            }
        }
        self::$openedFiles = self::$lockedFiles = [];

return $previousFiles;
    }

public static function compute(callable $callback, ItemInterface $item, bool &$save, CacheInterface $pool, \Closure $setMetadata = null, LoggerInterface $logger = null)
    {
        if ('\\' === \DIRECTORY_SEPARATOR && null === self::$lockedFiles) {
            // disable locking on Windows by default
            self::$files = self::$lockedFiles = [];
        }

$key = self::$files ? abs(crc32($item->getKey())) % \count(self::$files) : -1;

if ($key < 0 || self::$lockedFiles || !$lock = self::open($key)) {
            return $callback($item, $save);
        }

while (true) {
            try {
                $locked = false;
                // race to get the lock in non-blocking mode
                $locked = flock($lock, \LOCK_EX | \LOCK_NB, $wouldBlock);

if ($locked || !$wouldBlock) {
                    $logger && $logger->info(sprintf('Lock %s, now computing item "{key}"', $locked ? 'acquired' : 'not supported'), ['key' => $item->getKey()]);
                    self::$lockedFiles[$key] = true;

$value = $callback($item, $save);

if ($save) {
                        if ($setMetadata) {
                            $setMetadata($item);
                        }

$pool->save($item->set($value));
                        $save = false;
                    }

return $value;
                }
                // if we failed the race, retry locking in blocking mode to wait for the winner
                $logger && $logger->info('Item "{key}" is locked, waiting for it to be released', ['key' => $item->getKey()]);
                flock($lock, \LOCK_SH);
            } finally {
                flock($lock, \LOCK_UN);
                unset(self::$lockedFiles[$key]);
            }
            static $signalingException, $signalingCallback;
            $signalingException = $signalingException ?? unserialize("O:9:\"Exception\":1:{s:16:\"\0Exception\0trace\";a:0:{}}");
            $signalingCallback = $signalingCallback ?? function () use ($signalingException) { throw $signalingException; };

try {
                $value = $pool->get($item->getKey(), $signalingCallback, 0);
                $logger && $logger->info('Item "{key}" retrieved after lock was released', ['key' => $item->getKey()]);
                $save = false;

return $value;
            } catch (\Exception $e) {
                if ($signalingException !== $e) {
                    throw $e;
                }
                $logger && $logger->info('Item "{key}" not found while lock was released, now retrying', ['key' => $item->getKey()]);
            }
        }

return null;
    }

private static function open(int $key)
    {
        if (null !== $h = self::$openedFiles[$key] ?? null) {
            return $h;
        }
        set_error_handler(function () {});
        try {
            $h = fopen(self::$files[$key], 'r+');
        } finally {
            restore_error_handler();
        }

return self::$openedFiles[$key] = $h ?: @fopen(self::$files[$key], 'r');
    }
}

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