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<?php |
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/** |
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* The Cerberus class. |
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* |
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* @author Leandro Silva <[email protected]> |
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* @license https://github.com/mt-olympus/cerberus/blob/master/LICENSE MIT Licence |
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*/ |
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namespace Cerberus; |
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use Zend\Cache\Storage\StorageInterface; |
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/** |
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* The Cerberus Class. |
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* |
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* @author Leandro Silva <[email protected]> |
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* @license https://github.com/mt-olympus/cerberus/blob/master/LICENSE MIT Licence |
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*/ |
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class Cerberus implements CerberusInterface |
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{ |
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/** |
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* The storage object. |
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* |
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* @var \Zend\Cache\Storage\StorageInterface |
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*/ |
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private $storage; |
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/** |
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* Maximum number of failures to open the circuit. |
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* |
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* @var int |
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*/ |
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private $maxFailures; |
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/** |
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* Number of seconds to change from OPEN to HALF OPEN and try the connection again. |
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* |
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* @var int |
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*/ |
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private $timeout; |
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/** |
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* The default namespace used by the zend-cache storage. |
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* |
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* @var string |
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*/ |
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private $defaultNamespace; |
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/** |
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* Constructor. |
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* |
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* @param StorageInterface $storage The storage object |
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* @param int $maxFailures Maximum number of failures to open the circuit |
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* @param int $timeout Number of seconds to change from OPEN to HALF OPEN |
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*/ |
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public function __construct(StorageInterface $storage, $maxFailures = 5, $timeout = 30) |
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{ |
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$this->maxFailures = (int) $maxFailures; |
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$this->timeout = (int) $timeout; |
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$this->storage = $storage; |
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$this->defaultNamespace = $this->storage->getOptions()->getNamespace(); |
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} |
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/** |
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* {@inheritdoc} |
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* |
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* @see \Cerberus\CerberusInterface::isAvailable() |
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*/ |
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public function isAvailable($serviceName = null) |
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{ |
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return $this->getStatus($serviceName) !== CerberusInterface::OPEN; |
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} |
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/** |
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* {@inheritdoc} |
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* |
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* @see \Cerberus\CerberusInterface::getStatus() |
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*/ |
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public function getStatus($serviceName = null) |
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{ |
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$this->setNamespace($serviceName); |
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$success = false; |
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$failures = (int) $this->storage->getItem('failures', $success); |
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if (!$success) { |
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$failures = 0; |
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$this->storage->setItem('failures', $failures); |
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} |
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// Still has failures left |
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if ($failures < $this->maxFailures) { |
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return CerberusInterface::CLOSED; |
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} |
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$success = false; |
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$lastAttempt = $this->storage->getItem('last_attempt', $success); |
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// This is the first attempt after a failure, open the circuit |
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if (!$success) { |
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$lastAttempt = time(); |
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$this->storage->setItem('last_attempt', $lastAttempt); |
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return CerberusInterface::OPEN; |
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} |
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// Reached maxFailues but has passed the timeout limit, so we can try again |
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// We update the lastAttempt so only one call passes through |
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if (time() - $lastAttempt >= $this->timeout) { |
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$lastAttempt = time(); |
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$this->storage->setItem('last_attempt', $lastAttempt); |
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return CerberusInterface::HALF_OPEN; |
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} |
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return CerberusInterface::OPEN; |
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} |
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/** |
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* {@inheritdoc} |
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* |
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* @see \Cerberus\CerberusInterface::reportFailure() |
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*/ |
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public function reportFailure($serviceName = null) |
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{ |
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$this->setNamespace($serviceName); |
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$this->storage->incrementItem('failures', 1); |
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} |
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/** |
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* {@inheritdoc} |
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* |
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* @see \Cerberus\CerberusInterface::reportSuccess() |
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*/ |
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public function reportSuccess($serviceName = null) |
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{ |
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$this->setNamespace($serviceName); |
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$this->storage->setItem('failures', 0); |
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} |
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/** |
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* Sets the zend-cache storage namespace. |
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* |
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* @param string $serviceName |
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*/ |
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private function setNamespace($serviceName = null) |
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{ |
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if ($serviceName === null) { |
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$this->storage->getOptions()->setNamespace($this->defaultNamespace); |
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} else { |
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$this->storage->getOptions()->setNamespace($serviceName); |
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} |
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} |
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} |
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mt-olympus /
cerberus
Loading history...
If an expression can have both
false, andnullas possible values. It is generally a good practice to always use strict comparison to clearly distinguish between those two values.