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<?php |
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namespace Cmp\CircuitBreaker; |
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use Cmp\CircuitBreaker\Exception\ServiceAlreadyTrackedException; |
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use Cmp\CircuitBreaker\Exception\ServiceNotTrackedException; |
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use Psr\Log\NullLogger; |
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use Psr\SimpleCache\CacheInterface; |
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use Psr\Log\LoggerInterface; |
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/** |
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* Class CircuitBreaker |
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* |
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* @package Cmp\CircuitBreaker |
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*/ |
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class CircuitBreaker |
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{ |
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/** |
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* @var CacheInterface |
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*/ |
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protected $cache; |
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/** |
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* @var LoggerInterface |
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*/ |
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protected $logger; |
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/** |
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* @var Service[] |
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*/ |
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protected $services = []; |
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/** |
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* @var string |
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*/ |
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protected $cachePrefix = 'cb'; |
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/** |
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* @var int |
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*/ |
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protected $ttl = 3360; |
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/** |
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* CircuitBreaker constructor. |
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* |
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* @param CacheInterface $cache Cache to store the failures and times |
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* @param LoggerInterface|null $logger To log stuff |
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*/ |
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public function __construct( |
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CacheInterface $cache, |
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LoggerInterface $logger |
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) { |
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$this->cache = $cache; |
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$this->logger = $logger instanceof LoggerInterface ? $logger : new NullLogger(); |
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} |
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/** |
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* @param string $serviceName Name of the service |
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* @param string $field Field you want to fetch |
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* |
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* @return string |
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*/ |
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protected function getCacheKey($serviceName, $field) |
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{ |
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return $this->cachePrefix.'-'.$serviceName.'-'.$field; |
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} |
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/** |
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* @param $serviceName |
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* @return Service|null |
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*/ |
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protected function getService($serviceName) |
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{ |
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if (array_key_exists($serviceName, $this->services)) { |
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return $this->services[$serviceName]; |
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} |
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return null; |
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} |
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/** |
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* @param string $serviceName Name of the service |
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* |
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* @return int |
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*/ |
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protected function getFailures($serviceName) |
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{ |
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return (int) $this->cache->get($this->getCacheKey($serviceName, 'failures')); |
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} |
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/** |
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* @param string $serviceName Name of the service |
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* |
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* @return int |
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*/ |
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protected function getLastTest($serviceName) |
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{ |
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return (int) $this->cache->get($this->getCacheKey($serviceName, 'lastTest')); |
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} |
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/** |
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* @param string $serviceName Name of the service |
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* @param int $newValue New value to store |
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*/ |
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protected function setFailures($serviceName, $newValue) |
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{ |
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$this->cache->set($this->getCacheKey($serviceName, 'failures'), $newValue, $this->ttl); |
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$this->cache->set($this->getCacheKey($serviceName, 'lastTest'), time(), $this->ttl); |
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} |
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/** |
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* @param Service $service Service to track |
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* |
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* @throws ServiceAlreadyTrackedException |
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*/ |
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public function trackService(Service $service) |
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{ |
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if ($this->getService($service->getName()) !== null) { |
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throw new ServiceAlreadyTrackedException($service->getName()); |
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} |
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$this->services[$service->getName()] = $service; |
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} |
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/** |
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* @param string $serviceName Name of the service |
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* |
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* @return bool |
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* @throws ServiceNotTrackedException |
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*/ |
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public function isAvailable($serviceName) |
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{ |
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$service = $this->getService($serviceName); |
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if ($service == null) { |
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throw new ServiceNotTrackedException($serviceName); |
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} |
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$failures = $this->getFailures($serviceName); |
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$maxFailures = $service->getMaxFailures(); |
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if ($failures < $maxFailures) { |
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return true; |
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} |
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$lastTest = $this->getLastTest($serviceName); |
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$retryTimeout = $service->getRetryTimeout(); |
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if (($lastTest + $retryTimeout) < time()) { |
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$this->setFailures($serviceName, $failures); |
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$this->logger->info('Attempting service '.$serviceName.' one more time'); |
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return true; |
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} |
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return false; |
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} |
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/** |
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* @param string $serviceName Name of the service |
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* |
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* @throws ServiceNotTrackedException |
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*/ |
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public function reportFailure($serviceName) |
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{ |
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if ($this->getService($serviceName) == null) { |
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throw new ServiceNotTrackedException($serviceName); |
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} |
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$this->setFailures($serviceName, $this->getFailures($serviceName) + 1); |
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$this->logger->warning('Service '.$serviceName.' is shaky'); |
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} |
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/** |
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* @param string $serviceName Name of the service |
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* |
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* @throws ServiceNotTrackedException |
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*/ |
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public function reportSuccess($serviceName) |
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{ |
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$service = $this->getService($serviceName); |
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if ($service == null) { |
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throw new ServiceNotTrackedException($serviceName); |
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} |
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$failures = $this->getFailures($serviceName); |
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$maxFailures = $service->getMaxFailures(); |
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if ($failures > $maxFailures) { |
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$this->setFailures($serviceName, $maxFailures - 1); |
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$this->logger->alert('Service '.$serviceName.' is down'); |
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} elseif ($failures > 0) { |
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$this->setFailures($serviceName, $failures - 1); |
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} |
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} |
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} |
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CMProductions /
circuit-breaker
