Custom implementation of Sugar redis cache, using authentication and persistent connection

CustomSugarCacheRedis.php

<?php

// Enrico Simonetti
// enricosimonetti.com
//
// 2017-11-23 tested on Sugar 7.9.2.0 on PHP 7.1 with the addition of: https://gist.github.com/esimonetti/a99ea05b68cd2586949944c1b24b2921
// Custom implementation of Sugar redis cache, using authentication if configured and using persistent connections if configured
//
// file: custom/include/SugarCache/CustomSugarCacheRedis.php

// to enable, use the following config options:
// $sugar_config['external_cache_disabled_customredis'] = false;
// $sugar_config['external_cache_disabled_redis'] = true;

// to configure auth use the following config option:
// $sugar_config['external_cache']['redis']['auth'] = '<your redis auth password>';

// to configure persistent connection use the following config option:
// $sugar_config['external_cache']['redis']['persistent'] = true;

class CustomSugarCacheRedis extends SugarCacheRedis
{
    // decreased priority from 920 to 919 vs SugarCacheRedis, so that this will be used instead of SugarCacheRedis
    protected $_priority = 919;
    protected $_auth = '';
    protected $_persistent = false;

    /**
     * @see SugarCacheAbstract::useBackend()
     */
    public function useBackend()
    {
        // check grandparent, as parent would prevent it from running
        if (!SugarCacheAbstract::useBackend() ) {
            return false;
        }
        
        if ( extension_loaded("redis")
                && empty($GLOBALS['sugar_config']['external_cache_disabled_customredis'])
                && $this->_getRedisObject() ) {
            return true;
        }
            
        return false;
    }
 
    /**
     * Get the redis object; initialize if needed
     */
    protected function _getRedisObject()
    {
        try {
            if (!($this->_redis instanceOf Redis)) {

                $this->_redis = new Redis();
                $this->_host = SugarConfig::getInstance()->get('external_cache.redis.host', $this->_host);
                $this->_port = SugarConfig::getInstance()->get('external_cache.redis.port', $this->_port);
                $this->_auth = SugarConfig::getInstance()->get('external_cache.redis.auth', $this->_auth);
                $this->_persistent = SugarConfig::getInstance()->get('external_cache.redis.persistent', $this->_persistent);
                
                $method = 'connect';
                if ($this->_persistent) {
                    $method = 'pconnect';
                }
                
                if ($this->_redis->$method($this->_host, $this->_port)) {
                    if (!empty($this->_auth)) {
                        if (!$this->_redis->auth($this->_auth)) {
                            return false;
                        }
                    }
                } else {
                    return false;
                }
            }
        }
        catch (RedisException $e)
        {
            return false;
        }

        return $this->_redis;
    }
}