131 lines
5.0 KiB
PHP
131 lines
5.0 KiB
PHP
<?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\Cache\CacheItemInterface;
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use Psr\Cache\CacheItemPoolInterface;
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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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class LockRegistry
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{
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private static $save;
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private static $openedFiles = array();
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private static $lockedFiles = array();
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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 = array(
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'AbstractAdapter.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.'DoctrineAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'FilesystemAdapter.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.'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.'RedisAdapter.php',
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__DIR__.\DIRECTORY_SEPARATOR.'Adapter'.\DIRECTORY_SEPARATOR.'SimpleCacheAdapter.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 $k => $file) {
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flock($file, LOCK_UN);
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fclose($file);
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}
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self::$openedFiles = self::$lockedFiles = array();
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return $previousFiles;
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}
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/**
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* @internal
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*/
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public static function save(string $key, CacheItemPoolInterface $pool, CacheItemInterface $item, callable $callback, float $startTime, &$value): bool
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{
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self::$save = self::$save ?? \Closure::bind(
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function (CacheItemPoolInterface $pool, CacheItemInterface $item, $value, float $startTime) {
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if ($item instanceof CacheItem && $startTime && $item->expiry > $endTime = microtime(true)) {
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$item->newMetadata[CacheItem::METADATA_EXPIRY] = $item->expiry;
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$item->newMetadata[CacheItem::METADATA_CTIME] = 1000 * (int) ($endTime - $startTime);
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}
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$pool->save($item->set($value));
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return $value;
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},
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null,
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CacheItem::class
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);
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$key = self::$files ? crc32($key) % \count(self::$files) : -1;
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if ($key < 0 || (self::$lockedFiles[$key] ?? false) || !$lock = self::open($key)) {
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$value = (self::$save)($pool, $item, $callback($item), $startTime);
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return true;
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}
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try {
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// race to get the lock in non-blocking mode
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if (flock($lock, LOCK_EX | LOCK_NB)) {
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self::$lockedFiles[$key] = true;
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$value = (self::$save)($pool, $item, $callback($item), $startTime);
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return true;
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}
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// if we failed the race, retry locking in blocking mode to wait for the winner
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flock($lock, LOCK_SH);
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} finally {
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flock($lock, LOCK_UN);
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self::$lockedFiles[$key] = false;
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}
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return false;
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}
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private static function open(int $key)
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{
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if ($h = self::$openedFiles[$key] ?? null) {
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return $h;
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}
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if ($h = fopen(self::$files[$key], 'rb')) {
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return self::$openedFiles[$key] = $h;
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}
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}
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}
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