Chris@0: <?php
Chris@0: namespace GuzzleHttp;
Chris@0: 
Chris@0: use GuzzleHttp\Promise\PromiseInterface;
Chris@0: use GuzzleHttp\Promise\RejectedPromise;
Chris@0: use GuzzleHttp\Psr7;
Chris@0: use Psr\Http\Message\RequestInterface;
Chris@0: use Psr\Http\Message\ResponseInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Middleware that retries requests based on the boolean result of
Chris@0:  * invoking the provided "decider" function.
Chris@0:  */
Chris@0: class RetryMiddleware
Chris@0: {
Chris@0:     /** @var callable  */
Chris@0:     private $nextHandler;
Chris@0: 
Chris@0:     /** @var callable */
Chris@0:     private $decider;
Chris@0: 
Chris@0:     /**
Chris@0:      * @param callable $decider     Function that accepts the number of retries,
Chris@0:      *                              a request, [response], and [exception] and
Chris@0:      *                              returns true if the request is to be
Chris@0:      *                              retried.
Chris@0:      * @param callable $nextHandler Next handler to invoke.
Chris@0:      * @param callable $delay       Function that accepts the number of retries
Chris@0:      *                              and [response] and returns the number of
Chris@0:      *                              milliseconds to delay.
Chris@0:      */
Chris@0:     public function __construct(
Chris@0:         callable $decider,
Chris@0:         callable $nextHandler,
Chris@0:         callable $delay = null
Chris@0:     ) {
Chris@0:         $this->decider = $decider;
Chris@0:         $this->nextHandler = $nextHandler;
Chris@0:         $this->delay = $delay ?: __CLASS__ . '::exponentialDelay';
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Default exponential backoff delay function.
Chris@0:      *
Chris@0:      * @param $retries
Chris@0:      *
Chris@0:      * @return int
Chris@0:      */
Chris@0:     public static function exponentialDelay($retries)
Chris@0:     {
Chris@0:         return (int) pow(2, $retries - 1);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * @param RequestInterface $request
Chris@0:      * @param array            $options
Chris@0:      *
Chris@0:      * @return PromiseInterface
Chris@0:      */
Chris@0:     public function __invoke(RequestInterface $request, array $options)
Chris@0:     {
Chris@0:         if (!isset($options['retries'])) {
Chris@0:             $options['retries'] = 0;
Chris@0:         }
Chris@0: 
Chris@0:         $fn = $this->nextHandler;
Chris@0:         return $fn($request, $options)
Chris@0:             ->then(
Chris@0:                 $this->onFulfilled($request, $options),
Chris@0:                 $this->onRejected($request, $options)
Chris@0:             );
Chris@0:     }
Chris@0: 
Chris@0:     private function onFulfilled(RequestInterface $req, array $options)
Chris@0:     {
Chris@0:         return function ($value) use ($req, $options) {
Chris@0:             if (!call_user_func(
Chris@0:                 $this->decider,
Chris@0:                 $options['retries'],
Chris@0:                 $req,
Chris@0:                 $value,
Chris@0:                 null
Chris@0:             )) {
Chris@0:                 return $value;
Chris@0:             }
Chris@0:             return $this->doRetry($req, $options, $value);
Chris@0:         };
Chris@0:     }
Chris@0: 
Chris@0:     private function onRejected(RequestInterface $req, array $options)
Chris@0:     {
Chris@0:         return function ($reason) use ($req, $options) {
Chris@0:             if (!call_user_func(
Chris@0:                 $this->decider,
Chris@0:                 $options['retries'],
Chris@0:                 $req,
Chris@0:                 null,
Chris@0:                 $reason
Chris@0:             )) {
Chris@0:                 return \GuzzleHttp\Promise\rejection_for($reason);
Chris@0:             }
Chris@0:             return $this->doRetry($req, $options);
Chris@0:         };
Chris@0:     }
Chris@0: 
Chris@0:     private function doRetry(RequestInterface $request, array $options, ResponseInterface $response = null)
Chris@0:     {
Chris@0:         $options['delay'] = call_user_func($this->delay, ++$options['retries'], $response);
Chris@0: 
Chris@0:         return $this($request, $options);
Chris@0:     }
Chris@0: }