Whether plugins are singletons?

dmitry_fedyuk · June 18, 2017, 10:12pm

Yes.

Magento\Framework\Interception\Interceptor::___callPlugins

magento/magento2/blob/2.1.7/lib/internal/Magento/Framework/Interception/Interceptor.php#L106-L156


/**
 * Calls plugins for a given method.
 *
 * @param string $method
 * @param array $arguments
 * @param array $pluginInfo
 * @return mixed|null
 */
protected function ___callPlugins($method, array $arguments, array $pluginInfo)
{
    $capMethod = ucfirst($method);
    $result = null;
    if (isset($pluginInfo[DefinitionInterface::LISTENER_BEFORE])) {
        // Call 'before' listeners
        foreach ($pluginInfo[DefinitionInterface::LISTENER_BEFORE] as $code) {
            $pluginInstance = $this->pluginList->getPlugin($this->subjectType, $code);
            $pluginMethod = 'before' . $capMethod;
            $beforeResult = $pluginInstance->$pluginMethod($this, ...array_values($arguments));
            if ($beforeResult) {
                $arguments = $beforeResult;
            }
            unset($pluginInstance, $pluginMethod);
        }
    }
    if (isset($pluginInfo[DefinitionInterface::LISTENER_AROUND])) {
        // Call 'around' listener
        $chain = $this->chain;
        $type = $this->subjectType;
        /** @var \Magento\Framework\Interception\InterceptorInterface $subject */
        $subject = $this;
        $code = $pluginInfo[DefinitionInterface::LISTENER_AROUND];
        $next = function () use ($chain, $type, $method, $subject, $code) {
            return $chain->invokeNext($type, $method, $subject, func_get_args(), $code);
        };
        $pluginInstance = $this->pluginList->getPlugin($this->subjectType, $code);
        $pluginMethod = 'around' . $capMethod;
        $result = $pluginInstance->$pluginMethod($this, $next, ...array_values($arguments));
        unset($pluginInstance, $pluginMethod);
    } else {
        // Call original method
        $result = parent::$method(...array_values($arguments));
    }
    if (isset($pluginInfo[DefinitionInterface::LISTENER_AFTER])) {
        // Call 'after' listeners
        foreach ($pluginInfo[DefinitionInterface::LISTENER_AFTER] as $code) {
            $result = $this->pluginList->getPlugin($this->subjectType, $code)
                ->{'after' . $capMethod}($this, $result);
        }
    }
    return $result;
}

Magento\Framework\Interception\PluginList\PluginList::getPlugin()

github.com

magento/magento2/blob/2.1.7/lib/internal/Magento/Framework/Interception/PluginList/PluginList.php#L221-L236


/**
 * Retrieve plugin Instance
 *
 * @param string $type
 * @param string $code
 * @return mixed
 */
public function getPlugin($type, $code)
{
    if (!isset($this->_pluginInstances[$type][$code])) {
        $this->_pluginInstances[$type][$code] = $this->_objectManager->get(
            $this->_inherited[$type][$code]['instance']
        );
    }
    return $this->_pluginInstances[$type][$code];
}