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<?php |
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declare(strict_types=1); |
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namespace RateLimit; |
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use Memcached; |
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use RateLimit\Exception\CannotUseRateLimiter; |
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use RateLimit\Exception\LimitExceeded; |
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use function max; |
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use function sprintf; |
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use function time; |
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final class MemcachedRateLimiter implements RateLimiter, SilentRateLimiter |
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{ |
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private const MEMCACHED_SECONDS_LIMIT = 2592000; // 30 days in seconds |
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/** @var Memcached */ |
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private $memcached; |
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/** @var string */ |
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private $keyPrefix; |
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public function __construct(Memcached $memcached, string $keyPrefix = '') |
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{ |
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// @see https://www.php.net/manual/en/memcached.increment.php#111187 |
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if ($memcached->getOption(Memcached::OPT_BINARY_PROTOCOL) !== 1) { |
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throw new CannotUseRateLimiter('Memcached "OPT_BINARY_PROTOCOL" option should be set to "true".'); |
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} |
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$this->memcached = $memcached; |
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$this->keyPrefix = $keyPrefix; |
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} |
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public function limit(string $identifier, Rate $rate): void |
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{ |
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$limitKey = $this->limitKey($identifier, $rate->getInterval()); |
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$current = $this->getCurrent($limitKey); |
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if ($current >= $rate->getOperations()) { |
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throw LimitExceeded::for($identifier, $rate); |
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} |
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$this->updateCounter($limitKey, $rate->getInterval()); |
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} |
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public function limitSilently(string $identifier, Rate $rate): Status |
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{ |
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$interval = $rate->getInterval(); |
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$limitKey = $this->limitKey($identifier, $interval); |
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$timeKey = $this->timeKey($identifier, $interval); |
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$current = $this->getCurrent($limitKey); |
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if ($current <= $rate->getOperations()) { |
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$current = $this->updateCounterAndTime($limitKey, $timeKey, $interval); |
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} |
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return Status::from( |
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$identifier, |
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$current, |
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$rate->getOperations(), |
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time() + max(0, $interval - $this->getElapsedTime($timeKey)) |
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); |
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} |
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private function limitKey(string $identifier, int $interval): string |
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{ |
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return sprintf('%s%s:%d', $this->keyPrefix, $identifier, $interval); |
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} |
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private function timeKey(string $identifier, int $interval): string |
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{ |
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return sprintf('%s%s:%d:time', $this->keyPrefix, $identifier, $interval); |
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} |
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private function getCurrent(string $limitKey): int |
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{ |
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return (int) $this->memcached->get($limitKey); |
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} |
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private function updateCounterAndTime(string $limitKey, string $timeKey, int $interval): int |
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{ |
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$current = $this->updateCounter($limitKey, $interval); |
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if ($current === 1) { |
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$this->memcached->add($timeKey, time(), $this->intervalToMemcachedTime($interval)); |
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} |
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return $current; |
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} |
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private function updateCounter(string $limitKey, int $interval): int |
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{ |
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$current = $this->memcached->increment($limitKey, 1, 1, $this->intervalToMemcachedTime($interval)); |
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return $current === false ? 1 : $current; |
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} |
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private function getElapsedTime(string $timeKey): int |
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{ |
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return time() - (int) $this->memcached->get($timeKey); |
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} |
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/** |
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* Interval to Memcached expiration time. |
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* |
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* @see https://www.php.net/manual/en/memcached.expiration.php |
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* |
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* @param int $interval |
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* @return int |
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*/ |
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private function intervalToMemcachedTime(int $interval): int |
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{ |
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return $interval <= self::MEMCACHED_SECONDS_LIMIT ? $interval : time() + $interval; |
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} |
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} |
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nikolaposa /
rate-limit
