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<?php |
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namespace SchulzeFelix\AdWords; |
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/** |
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* Exponential backoff implementation. |
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*/ |
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class ExponentialBackoff |
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{ |
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const MAX_DELAY_MICROSECONDS = 120000000; |
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/** |
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* @var int |
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*/ |
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private $retries; |
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/** |
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* @var callable |
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*/ |
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private $retryFunction; |
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/** |
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* @var callable |
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*/ |
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private $delayFunction; |
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/** |
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* @param int $retries [optional] Number of retries for a failed request. |
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* @param callable $retryFunction [optional] returns bool for whether or not to retry |
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*/ |
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public function __construct($retries = null, callable $retryFunction = null) |
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{ |
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$this->retries = $retries !== null ? (int) $retries : 3; |
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$this->retryFunction = $retryFunction; |
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$this->delayFunction = function ($delay) { |
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usleep($delay); |
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}; |
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} |
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/** |
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* Executes the retry process. |
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* |
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* @param callable $function |
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* @param array $arguments [optional] |
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* @return mixed |
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* @throws \Exception The last exception caught while retrying. |
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*/ |
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public function execute(callable $function, array $arguments = []) |
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{ |
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$delayFunction = $this->delayFunction; |
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$retryAttempt = 0; |
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$exception = null; |
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while (true) { |
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try { |
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return call_user_func_array($function, $arguments); |
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} catch (\Exception $exception) { |
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if ($this->retryFunction) { |
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if (! call_user_func($this->retryFunction, $exception)) { |
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throw $exception; |
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} |
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} |
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if ($exception->getCode() == 403) { |
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break; |
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} |
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if ($retryAttempt >= $this->retries) { |
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break; |
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} |
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$delayFunction($this->calculateDelay($retryAttempt)); |
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$retryAttempt++; |
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} |
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} |
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throw $exception; |
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} |
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/** |
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* @param callable $delayFunction |
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* @return void |
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*/ |
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public function setDelayFunction(callable $delayFunction) |
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{ |
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$this->delayFunction = $delayFunction; |
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} |
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/** |
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* Calculates exponential delay. |
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* |
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* @param int $attempt |
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* @return int |
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*/ |
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private function calculateDelay($attempt) |
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{ |
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return min( |
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mt_rand(0, 1000000) + (pow(2, $attempt) * 1000000), |
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self::MAX_DELAY_MICROSECONDS |
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); |
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} |
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} |
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