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