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Merge pull request #61 from paragonie/short-lived-cache
Optional feature: Cache responses for a very short period of time.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,12 @@ | ||
| <?php | ||
| declare(strict_types=1); | ||
| namespace ParagonIE\Chronicle\Exception; | ||
|
|
||
| /** | ||
| * Class CacheMisuseException | ||
| * @package ParagonIE\Chronicle\Exception | ||
| */ | ||
| class CacheMisuseException extends BaseException | ||
| { | ||
|
|
||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,192 @@ | ||
| <?php | ||
| declare(strict_types=1); | ||
| namespace ParagonIE\Chronicle; | ||
|
|
||
| use Cache\Adapter\Memcached\MemcachedCachePool; | ||
| use ParagonIE\Chronicle\Exception\CacheMisuseException; | ||
| use ParagonIE\ConstantTime\Base32; | ||
| use Psr\Cache\CacheItemInterface; | ||
| use Psr\Http\Message\ResponseInterface; | ||
| use Psr\Http\Message\StreamInterface; | ||
| use Slim\Http\Headers; | ||
| use Slim\Http\Response; | ||
| use Slim\Http\Stream; | ||
|
|
||
| /** | ||
| * Class ResponseCache | ||
| * @package ParagonIE\Chronicle | ||
| */ | ||
| class ResponseCache | ||
| { | ||
| /** @var string $cacheKey */ | ||
| private $cacheKey = ''; | ||
|
|
||
| /** @var int|null $lifetime */ | ||
| private $lifetime; | ||
|
|
||
| /** @var MemcachedCachePool $memcached */ | ||
| private $memcached; | ||
|
|
||
| /** | ||
| * ResponseCache constructor. | ||
| * @param int $lifetime | ||
| * @throws \Psr\Cache\InvalidArgumentException | ||
| * @throws CacheMisuseException | ||
| */ | ||
| public function __construct(int $lifetime = 0) | ||
| { | ||
| if (!self::isAvailable()) { | ||
| throw new CacheMisuseException('Memcached is not installed.'); | ||
| } | ||
| $client = new \Memcached(); | ||
| $client->addServer('localhost', 11211); | ||
| if ($lifetime > 0) { | ||
| $this->lifetime = $lifetime; | ||
| } | ||
| $this->memcached = new MemcachedCachePool($client); | ||
| $this->loadCacheKey(); | ||
| } | ||
|
|
||
| /** | ||
| * @return string | ||
| * @throws \Psr\Cache\InvalidArgumentException | ||
| * @throws CacheMisuseException | ||
| */ | ||
| public function loadCacheKey() | ||
| { | ||
| if (!empty($this->cacheKey)) { | ||
| return $this->cacheKey; | ||
| } | ||
| if ($this->memcached->hasItem('ChronicleCacheKey')) { | ||
| /** @var CacheItemInterface $item */ | ||
| $item = $this->memcached->getItem('ChronicleCacheKey'); | ||
| return (string) $item->get(); | ||
| } | ||
| try { | ||
| $key = sodium_crypto_shorthash_keygen(); | ||
| } catch (\Throwable $ex) { | ||
| throw new CacheMisuseException('CSPRNG failure', 0, $ex); | ||
| } | ||
| /** @var CacheItemInterface $item */ | ||
| $item = $this->memcached->getItem('ChronicleCacheKey'); | ||
| $item->set($key); | ||
| $item->expiresAfter(null); | ||
| $this->memcached->save($item); | ||
| return $key; | ||
| } | ||
|
|
||
| /** | ||
| * @return bool | ||
| */ | ||
| public static function isAvailable(): bool | ||
| { | ||
| return extension_loaded('memcached') && class_exists('Memcached'); | ||
| } | ||
|
|
||
| /** | ||
| * @param string $input | ||
| * @return string | ||
| * @throws CacheMisuseException | ||
| * @throws \Psr\Cache\InvalidArgumentException | ||
| * @throws \SodiumException | ||
| */ | ||
| public function getCacheKey(string $input): string | ||
| { | ||
| return 'Chronicle|' . Base32::encodeUnpadded( | ||
| sodium_crypto_shorthash($input, $this->loadCacheKey()) | ||
| ); | ||
| } | ||
|
|
||
| /** | ||
| * @param string $uri | ||
| * @return Response|null | ||
| * @throws CacheMisuseException | ||
| * @throws \Psr\Cache\InvalidArgumentException | ||
| * @throws \SodiumException | ||
| */ | ||
| public function loadResponse(string $uri) | ||
| { | ||
| $key = $this->getCacheKey($uri); | ||
| if (!$this->memcached->hasItem($key)) { | ||
| return null; | ||
| } | ||
| /** @var CacheItemInterface $item */ | ||
| $item = $this->memcached->getItem($key); | ||
| /** @var string|null $cached */ | ||
| $cached = $item->get(); | ||
| if (!is_string($cached)) { | ||
| return null; | ||
| } | ||
| return $this->deserializeResponse($cached); | ||
| } | ||
|
|
||
| /** | ||
| * @param string $uri | ||
| * @param ResponseInterface $response | ||
| * @return void | ||
| * @throws CacheMisuseException | ||
| * @throws \Psr\Cache\InvalidArgumentException | ||
| * @throws \SodiumException | ||
| */ | ||
| public function saveResponse(string $uri, ResponseInterface $response) | ||
| { | ||
| $key = $this->getCacheKey($uri); | ||
| /** @var CacheItemInterface $item */ | ||
| $item = $this->memcached->getItem($key); | ||
| $item->set($this->serializeResponse($response)); | ||
| $item->expiresAfter($this->lifetime); | ||
| $this->memcached->save($item); | ||
| } | ||
|
|
||
| /** | ||
| * @param string $serialized | ||
| * @return Response | ||
| */ | ||
| public function deserializeResponse(string $serialized): Response | ||
| { | ||
| /** @var array<string, string|array|int> $decoded */ | ||
| $decoded = json_decode($serialized, true); | ||
| $status = (int) $decoded['status']; | ||
| $headers = (array) $decoded['headers']; | ||
| /** @var string $body */ | ||
| $body = $decoded['body']; | ||
|
|
||
| return new Response( | ||
| $status, | ||
| new Headers($headers), | ||
| self::fromString($body) | ||
| ); | ||
| } | ||
|
|
||
| /** | ||
| * Create a Stream object from a string. | ||
| * | ||
| * @param string $input | ||
| * @return StreamInterface | ||
| * @throws \Error | ||
| */ | ||
| public static function fromString(string $input): StreamInterface | ||
| { | ||
| /** @var resource $stream */ | ||
| $stream = \fopen('php://temp', 'w+'); | ||
| if (!\is_resource($stream)) { | ||
| throw new \Error('Could not create stream'); | ||
| } | ||
| \fwrite($stream, $input); | ||
| \rewind($stream); | ||
| return new Stream($stream); | ||
| } | ||
|
|
||
| /** | ||
| * @param ResponseInterface $response | ||
| * @return string | ||
| */ | ||
| public function serializeResponse(ResponseInterface $response): string | ||
| { | ||
| return json_encode([ | ||
| 'status' => $response->getStatusCode(), | ||
| 'headers' => $response->getHeaders(), | ||
| 'body' => $response->getBody()->getContents() | ||
| ]); | ||
| } | ||
| } |
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