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<?php |
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namespace BehEh\Flaps\Throttling; |
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use BehEh\Flaps\ThrottlingStrategyInterface; |
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use InvalidArgumentException; |
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use BehEh\Flaps\StorageInterface; |
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use LogicException; |
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/** |
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* This strategy allows a certain number of requests by an entity in a specific timespan. |
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* Additionally, once at least one request per timespan is tracked, the number of requests |
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* will be continuously reduced so that after the duration specified by timespan the specified |
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* number of requests are allowed again. |
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* |
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* @since 0.1 |
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* @author Benedict Etzel <[email protected]> |
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*/ |
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class LeakyBucketStrategy implements ThrottlingStrategyInterface |
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{ |
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/** |
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* @var int |
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*/ |
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protected $requestsPerTimeSpan; |
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/** |
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* Sets the maximum number of requests allowed per timespan for a single entity. |
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* @param int $requests |
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* @throws \InvalidArgumentException |
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*/ |
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public function setRequestsPerTimeSpan($requests) |
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{ |
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if (!is_numeric($requests)) { |
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throw new InvalidArgumentException('requests per timespan is not numeric'); |
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} |
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$requests = (int) $requests; |
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if ($requests < 1) { |
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throw new InvalidArgumentException('requests per timespan cannot be smaller than 1'); |
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} |
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$this->requestsPerTimeSpan = $requests; |
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} |
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/** |
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* Returns the previously set number of requests per timespan. |
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* @return int |
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*/ |
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public function getRequestsPerTimeSpan() |
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{ |
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return $this->requestsPerTimeSpan; |
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} |
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/** |
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* @var float |
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*/ |
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protected $timeSpan; |
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/** |
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* Sets the timespan in which the defined number of requests is allowed per single entity. |
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* @param float|string $timeSpan |
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* @throws InvalidArgumentException |
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*/ |
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public function setTimeSpan($timeSpan) |
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{ |
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if (is_string($timeSpan)) { |
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$timeSpan = self::parseTime($timeSpan); |
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} |
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if (!is_numeric($timeSpan)) { |
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throw new InvalidArgumentException('timespan is not numeric'); |
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} |
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$timeSpan = floatval($timeSpan); |
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if ($timeSpan <= 0) { |
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throw new InvalidArgumentException('timespan cannot be 0 or less'); |
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} |
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$this->timeSpan = $timeSpan; |
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} |
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/** |
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* Returns the previously set timespan. |
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* @return float |
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*/ |
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public function getTimeSpan() |
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{ |
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return (float) $this->timeSpan; |
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} |
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/** |
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* Sets the strategy up with $requests allowed per $timeSpan |
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* @param int $requests the requests allowed per time span |
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* @param int|string $timeSpan tither the amount of seconds or a string such as "10s", "5m" or "1h" |
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* @throws InvalidArgumentException |
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* @see LeakyBucketStrategy::setRequestsPerTimeSpan |
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* @see LeakyBucketStrategy::setTimeSpan |
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*/ |
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public function __construct($requests, $timeSpan) |
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{ |
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$this->setRequestsPerTimeSpan($requests); |
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$this->setTimeSpan($timeSpan); |
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} |
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/** |
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* @var StorageInterface |
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*/ |
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protected $storage; |
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public function setStorage(StorageInterface $storage) |
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{ |
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$this->storage = $storage; |
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} |
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/** |
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* Parses a timespan string such as "10s", "5m" or "1h" and returns the amount of seconds. |
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* @param string $timeSpan the time span to parse to seconds |
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* @return float|null the number of seconds or null, if $timeSpan couldn't be parsed |
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*/ |
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public static function parseTime($timeSpan) |
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{ |
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$times = array('s' => 1, 'm' => 60, 'h' => 3600, 'd' => 86400, 'w' => 604800); |
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$matches = array(); |
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if (is_numeric($timeSpan)) { |
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return $timeSpan; |
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} |
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if (preg_match('/^((\d+)?(\.\d+)?)('.implode('|', array_keys($times)).')$/', |
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$timeSpan, $matches)) { |
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return floatval($matches[1]) * $times[$matches[4]]; |
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} |
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return null; |
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} |
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/** |
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* Returns whether entity exceeds it's allowed request capacity with this request. |
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* @param string $identifier the identifer of the entity to check |
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* @return bool true if this requests exceeds the number of requests allowed |
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* @throws LogicException if no storage has been set |
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*/ |
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public function isViolator($identifier) |
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{ |
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if ($this->storage === null) { |
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throw new LogicException('no storage set'); |
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} |
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$time = microtime(true); |
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$timestamp = $time; |
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$rate = (float) $this->requestsPerTimeSpan / $this->timeSpan; |
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$identifier = 'leaky:'.sha1($rate.$identifier); |
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$requestCount = $this->storage->getValue($identifier); |
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if ($requestCount > 0) { |
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$secondsSince = $time - $this->storage->getTimestamp($identifier); |
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$reduceBy = floor($secondsSince * $rate); |
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$unfinishedSeconds = fmod($secondsSince, $rate); |
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$requestCount = max($requestCount - $reduceBy, 0); |
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if ($requestCount > 0) { |
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$timestamp = $time - ($rate - $unfinishedSeconds); |
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} |
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} |
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if ($requestCount + 1 > $this->requestsPerTimeSpan) { |
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return true; |
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} |
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$requestCount++; |
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$this->storage->setValue($identifier, $requestCount); |
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$this->storage->setTimestamp($identifier, $timestamp); |
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$this->storage->expireIn($identifier, $requestCount / $rate); |
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return false; |
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} |
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} |
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beheh /
flaps
