Symfony框架中间件：实现多级缓存和数据自动同步的功能

<?php

use SymfonyComponentHttpKernelEventControllerEvent;
use PsrCacheCacheItemPoolInterface;

class CacheMiddleware
{
    private $localCache;
    private $distributedCache;
    private $persistenceCache;
    
    public function __construct(CacheItemPoolInterface $localCache, CacheItemPoolInterface $distributedCache, CacheItemPoolInterface $persistenceCache)
    {
        $this->localCache = $localCache;
        $this->distributedCache = $distributedCache;
        $this->persistenceCache = $persistenceCache;
    }
    
    public function onKernelController(ControllerEvent $event)
    {
        $request = $event->getRequest();
        $cacheKey = $this->generateCacheKey($request);
        
        // 尝试从本地缓存读取数据
        $cacheItem = $this->localCache->getItem($cacheKey);
        if ($cacheItem->isHit()) {
            $response = $cacheItem->get();
            $event->setResponse($response);
            return;
        }
        
        // 尝试从分布式缓存读取数据
        $cacheItem = $this->distributedCache->getItem($cacheKey);
        if ($cacheItem->isHit()) {
            $response = $cacheItem->get();
            // 更新本地缓存
            $this->localCache->save($cacheItem);
            $event->setResponse($response);
            return;
        }
        
        // 从持久化缓存读取数据
        $cacheItem = $this->persistenceCache->getItem($cacheKey);
        if ($cacheItem->isHit()) {
            $response = $cacheItem->get();
            // 更新本地缓存和分布式缓存
            $this->localCache->save($cacheItem);
            $this->distributedCache->save($cacheItem);
            $event->setResponse($response);
            return;
        }
        
        // 如果都没有命中缓存，则执行正常业务逻辑
        $response = $event->getController()($request);
        
        // 将结果保存到缓存
        $cacheItem->set($response);
        $this->localCache->save($cacheItem);
        $this->distributedCache->save($cacheItem);
        $this->persistenceCache->save($cacheItem);
        
        $event->setResponse($response);
    }
    
    private function generateCacheKey(Request $request)
    {
        // 根据Request对象生成唯一的缓存键
        return md5($request->getPathInfo() . $request->getQueryString());
    }
}