README

This is an Implementation of the 2-state (Open and Closed) CircuitBreaker pattern that we use at HolidayPirates.
Unlike the 3-state CircuitBreaker proposed by Fowler, this implementation has only two states, "Open" and "Closed".

Install

Via Composer

$ composer require holidaypirates/pirate-circuit-breaker

Requirements

• PHP 7.3
• An implementation of the \Psr\SimpleCache\CacheInterface to store the services failures and circuit state OR your own storage implementation of \HolidayPirates\CircuitBreaker\Storage\StorageInterface
• For development only : Docker and Docker-Compose

Usage

<?php declare(strict_types=1);

use HolidayPirates\CircuitBreaker\CircuitBreaker;
use HolidayPirates\CircuitBreaker\Service\DummyService;
use HolidayPirates\CircuitBreaker\Storage\Adapter\SimpleCacheAdapter;

// Setup:
$pool = new YourCachePool(); // Any implementation of \Psr\SimpleCache\CacheInterface
$storageAdapter = new SimpleCacheAdapter($pool);
$circuitBreaker = new CircuitBreaker($storageAdapter);

$service = new DummyService(5, 60); //After 5 failed attempts it will wait 60 seconds before allowing more requests.

$circuitBreaker->registerService($service);

// Usage:
$dummyApiClient = new DummyApiClient(); // This will be any service you want to protect with the CB

if (false == $circuitBreaker->isServiceAvailable(DummyService::class)) {
    throw new \Exception('Service unavailable');
}

try {
    $response = $dummyApiClient->sendRequest();
    $circuitBreaker->reportSuccess(DummyService::class);
} catch (Exception $exception) {
    $circuitBreaker->reportFailure(DummyService::class);
       
    throw new \Exception('Service unavailable',0, $exception);
}

Please note that HolidayPirates\CircuitBreaker\Service\DummyService is just an implementation of \HolidayPirates\CircuitBreaker\Service\ServiceInterface.
You must create your own implementations of \HolidayPirates\CircuitBreaker\Service\ServiceInterface for each service that you want the CircuitBreaker to operate in.

For more examples of usage please see \HolidayPirates\Tests\Integration\CircuitBreaker\CircuitBreakerTest

Testing

$ docker-compose run php vendor/bin/phpunit

Credits

• Ricardo Fiorani
• All Contributors

License

The MIT License (MIT). Please see License File for more information.