PHP code example of postcon / resilience

1. Go to this page and download the library: Download postcon/resilience library. Choose the download type require.

2. Extract the ZIP file and open the index.php.

3. Add this code to the index.php.
    
        
<?php
require_once('vendor/autoload.php');

/* Start to develop here. Best regards https://php-download.com/ */

    

postcon / resilience example snippets


$redis = new \Redis();

$circuitBreaker = new \Postcon\Resilience\RedisCircuitBreaker($redis, 'system', 120, 3);
$circuitBreaker->reportSuccess();

$circuitBreaker->isAvailable(); // should be true
$circuitBreaker->reportFailure();
$circuitBreaker->isAvailable(); // ... still true
$circuitBreaker->reportFailure();
$circuitBreaker->isAvailable(); // ... still true
$circuitBreaker->reportFailure();
$circuitBreaker->isAvailable(); // ... now it is false

$circuitBreaker->check(); // throws CircuitBreakerTripped exception, if 'system' is not available.

use GuzzleHttp\ClientInterface;
use GuzzleHttp\Exception\ClientException;
use GuzzleHttp\Exception\ConnectException;
use GuzzleHttp\Exception\GuzzleException;
use GuzzleHttp\Exception\ServerException;
use Postcon\Resilience\CircuitBreakerInterface;
use Postcon\Resilience\CircuitBreakerTripped;
use Psr\Http\Message\RequestInterface;

class CircuitBreakerClientDecorator implements ClientInterface
{
    /** @var ClientInterface */
    private $baseClient;

    /** @var CircuitBreakerInterface */
    private $circuitBreaker;

    public function __construct(ClientInterface $baseClient, CircuitBreakerInterface $circuitBreaker)
    {
        $this->baseClient     = $baseClient;
        $this->circuitBreaker = $circuitBreaker;
    }

    /**
     * @inheritdoc
     *
     * @throws CircuitBreakerTripped
     */
    public function send(RequestInterface $request, array $options = [])
    {
        return $this->check(function () use ($request, $options) {
            $this->baseClient->send($request, $options);
        });
    }

    // ...

    /**
     * @throws GuzzleException
     * @throws CircuitBreakerTripped
     */
    private function check(callable $function)
    {
        $this->circuitBreaker->check();

        try {
            $result = $function();

            $this->circuitBreaker->reportSuccess();

            return $result;
        } catch (ConnectException $e) {
            $this->circuitBreaker->reportFailure();
            throw $e;
        } catch (ServerException $e) {
            $this->circuitBreaker->reportFailure();
            throw $e;
        } catch (ClientException $e) {
            $this->circuitBreaker->reportSuccess();
            throw $e;
        }
    }
}

 --------------------------      ::reportSuccess()        ---------------------------
|          CLOSED          | <-------------------------- |            OPEN           |
| ::isAvailable() === true |    exceeding lifetime       | ::isAvailable() === false |
 --------------------------                               ---------------------------
       ^      |                                                                 ^
       |      |   ::reportFailure()                                             |
       |       -------------------------                                        |
       |                                |                                       |
       |                                v                                       |
       |  ::reportSuccess()   --------------------------                        |
        -------------------- |         HALF OPEN        | ----------------------
         exceeding lifetime  | ::isAvailable() === true |  rpt. ::reportFailure()
                              --------------------------