This will add a collector to handle Doctrine’s second-level cache and display basic information on puts, hits and misses on your PHP DebugBar.

<?php

namespace Utilities\DebugBar;

use DebugBar\DataCollector\DataCollector;
use DebugBar\DataCollector\Renderable;
use Doctrine\ORM\Cache\Logging\StatisticsCacheLogger;

/**
 * Handles the second-level cache statistics
 */
class SecondLevelCollector extends DataCollector implements Renderable
{
    /**
     * @var StatisticsCacheLogger
     */
    protected $logger;

    /**
     * @param StatisticsCacheLogger $logger
     */
    public function __construct(StatisticsCacheLogger $logger)
    {
        $this->logger = $logger;
    }

    /**
     * @return array
     */
    public function collect()
    {
        return [
            'stats' => implode(',', [
                'puts' => $this->logger->getPutCount(),
                'hits' => $this->logger->getHitCount(),
                'misses' => $this->logger->getMissCount(),
            ])
        ];
    }

    /**
     * @return string
     */
    public function getName()
    {
        return 'second_level';
    }

    /**
     * @return array
     */
    public function getWidgets()
    {
        return [
            "second_level" => [
                "icon" => "database",
                "map" => "second_level.stats",
                "tooltip" => 'Second-level Cache (puts, hits, misses)',
                "default" => "[]"
            ]
        ];
    }
}

Then instantiate the cache logger, set it to the cache config and add it to the new collector.

/** $config Doctrine\ORM\Configuration */

$cacheLogger = new \Doctrine\ORM\Cache\Logging\StatisticsCacheLogger();   
$config->getSecondLevelCacheConfiguration()->setCacheLogger($cacheLogger);
$debugbar->addCollector(new SecondLevelCollector($cacheLogger));