RetryPlugin.php

<?php

declare(strict_types=1);

namespace Http\Client\Common\Plugin;

use Http\Client\Common\Plugin;
use Http\Client\Exception\HttpException;
use Http\Promise\Promise;
use Psr\Http\Client\ClientExceptionInterface;
use Psr\Http\Message\RequestInterface;
use Psr\Http\Message\ResponseInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

/**
 * Retry the request if an exception is thrown.
 *
 * By default will retry only one time.
 *
 * @author Joel Wurtz <joel.wurtz@gmail.com>
 */
final class RetryPlugin implements Plugin
{
    /**
     * Number of retry before sending an exception.
     *
     * @var int
     */
    private $retry;

    /**
     * @var callable
     */
    private $errorResponseDelay;

    /**
     * @var callable
     */
    private $errorResponseDecider;

    /**
     * @var callable
     */
    private $exceptionDecider;

    /**
     * @var callable
     */
    private $exceptionDelay;

    /**
     * Store the retry counter for each request.
     *
     * @var array
     */
    private $retryStorage = [];

    /**
     * @param array{'retries'?: int, 'error_response_decider'?: callable, 'exception_decider'?: callable, 'error_response_delay'?: callable, 'exception_delay'?: callable} $config
     *
     * Configuration options:
     *   - retries: Number of retries to attempt if an exception occurs before letting the exception bubble up
     *   - error_response_decider: A callback that gets a request and response to decide whether the request should be retried
     *   - exception_decider: A callback that gets a request and an exception to decide after a failure whether the request should be retried
     *   - error_response_delay: A callback that gets a request and response and the current number of retries and returns how many microseconds we should wait before trying again
     *   - exception_delay: A callback that gets a request, an exception and the current number of retries and returns how many microseconds we should wait before trying again
     */
    public function __construct(array $config = [])
    {
        $resolver = new OptionsResolver();
        $resolver->setDefaults([
            'retries' => 1,
            'error_response_decider' => function (RequestInterface $request, ResponseInterface $response) {
                // do not retry client errors
                return $response->getStatusCode() >= 500 && $response->getStatusCode() < 600;
            },
            'exception_decider' => function (RequestInterface $request, ClientExceptionInterface $e) {
                // do not retry client errors
                return !$e instanceof HttpException || $e->getCode() >= 500 && $e->getCode() < 600;
            },
            'error_response_delay' => __CLASS__.'::defaultErrorResponseDelay',
            'exception_delay' => __CLASS__.'::defaultExceptionDelay',
        ]);

        $resolver->setAllowedTypes('retries', 'int');
        $resolver->setAllowedTypes('error_response_decider', 'callable');
        $resolver->setAllowedTypes('exception_decider', 'callable');
        $resolver->setAllowedTypes('error_response_delay', 'callable');
        $resolver->setAllowedTypes('exception_delay', 'callable');
        $options = $resolver->resolve($config);

        $this->retry = $options['retries'];
        $this->errorResponseDecider = $options['error_response_decider'];
        $this->errorResponseDelay = $options['error_response_delay'];
        $this->exceptionDecider = $options['exception_decider'];
        $this->exceptionDelay = $options['exception_delay'];
    }

    public function handleRequest(RequestInterface $request, callable $next, callable $first): Promise
    {
        $chainIdentifier = spl_object_hash((object) $first);

        return $next($request)->then(function (ResponseInterface $response) use ($request, $next, $first, $chainIdentifier) {
            if (!array_key_exists($chainIdentifier, $this->retryStorage)) {
                $this->retryStorage[$chainIdentifier] = 0;
            }

            if ($this->retryStorage[$chainIdentifier] >= $this->retry) {
                unset($this->retryStorage[$chainIdentifier]);

                return $response;
            }

            if (call_user_func($this->errorResponseDecider, $request, $response)) {
                /** @var int $time */
                $time = call_user_func($this->errorResponseDelay, $request, $response, $this->retryStorage[$chainIdentifier]);
                $response = $this->retry($request, $next, $first, $chainIdentifier, $time);
            }

            if (array_key_exists($chainIdentifier, $this->retryStorage)) {
                unset($this->retryStorage[$chainIdentifier]);
            }

            return $response;
        }, function (ClientExceptionInterface $exception) use ($request, $next, $first, $chainIdentifier) {
            if (!array_key_exists($chainIdentifier, $this->retryStorage)) {
                $this->retryStorage[$chainIdentifier] = 0;
            }

            if ($this->retryStorage[$chainIdentifier] >= $this->retry) {
                unset($this->retryStorage[$chainIdentifier]);

                throw $exception;
            }

            if (!call_user_func($this->exceptionDecider, $request, $exception)) {
                throw $exception;
            }

            /** @var int $time */
            $time = call_user_func($this->exceptionDelay, $request, $exception, $this->retryStorage[$chainIdentifier]);

            return $this->retry($request, $next, $first, $chainIdentifier, $time);
        });
    }

    /**
     * @param int $retries The number of retries we made before. First time this get called it will be 0.
     */
    public static function defaultErrorResponseDelay(RequestInterface $request, ResponseInterface $response, int $retries): int
    {
        return pow(2, $retries) * 500000;
    }

    /**
     * @param int $retries The number of retries we made before. First time this get called it will be 0.
     */
    public static function defaultExceptionDelay(RequestInterface $request, ClientExceptionInterface $e, int $retries): int
    {
        return pow(2, $retries) * 500000;
    }

    /**
     * @throws \Exception if retrying returns a failed promise
     */
    private function retry(RequestInterface $request, callable $next, callable $first, string $chainIdentifier, int $delay): ResponseInterface
    {
        usleep($delay);

        // Retry synchronously
        ++$this->retryStorage[$chainIdentifier];
        $promise = $this->handleRequest($request, $next, $first);

        return $promise->wait();
    }
}