Driver_Database_Driver_Mongo::_connect

protected function _connect()
{
    $database = $hostname = $port = $username = $password = $persistent = $readpreference = null;
    extract($this->config['connection']);

    if (!$port>0)
    {
        $port = 27017;
    }

    # 检查下是否已经有连接连上去了
    if (Database_Driver_Mongo::$_connection_instance)
    {
        if (is_array($hostname))
        {
            $hostconfig = $hostname[$this->_connection_type];
            if (!$hostconfig)
            {
                throw new Exception('指定的数据库连接主从配置中('.$this->_connection_type.')不存在，请检查配置');
            }
            if (!is_array($hostconfig))
            {
                $hostconfig = array($hostconfig);
            }
        }
        else
        {
            $hostconfig = array
            (
                $hostname
            );
        }

        # 先检查是否已经有相同的连接连上了数据库
        foreach ($hostconfig as $host)
        {
            $_connection_id = $this->_get_connection_hash($host, $port, $username);

            if (isset(Database_Driver_Mongo::$_connection_instance[$_connection_id]))
            {
                $this->_connection_ids[$this->_connection_type] = $_connection_id;

                return;
            }
        }

    }

    // 获取所有的主数据库
    if (is_array($this->config['connection']['hostname']))
    {
        if (is_array($this->config['connection']['hostname']['master']))
        {
            $all_master_hosts = $this->config['connection']['hostname']['master'];
        }
        else
        {
            $all_master_hosts = array
            (
                $this->config['connection']['hostname']['master']
            );
        }
    }
    else
    {
        $all_master_hosts = array
        (
            $this->config['connection']['hostname']
        );
    }

    # 错误服务器
    static $error_host = array();

    $last_error = null;
    while (true)
    {
        $hostname = $this->_get_rand_host($error_host);
        if (false===$hostname)
        {
            Core::debug()->error($error_host,'error_host');

            if ($last_error)throw $last_error;
            throw new Exception('connect mongodb server error.');
        }

        $_connection_id = $this->_get_connection_hash($hostname, $port, $username);
        Database_Driver_Mongo::$_current_connection_id_to_hostname[$_connection_id] = $hostname.':'.$port;

        try
        {
            $time = microtime(true);

            $options = array();

            // 所有非主数据库都加上replicaSet参数
            if (!in_array($hostname, $all_master_hosts))
            {
                $options['replicaSet'] = true;
            }

            // 长连接设计
            if ($persistent)
            {
                $options['persist'] = is_string($persistent)?$persistent:'x';
            }

            static $mclass = null;
            if (null===$mclass)
            {
                $mclass = class_exists('MongoClient', false)?'MongoClient':'Mongo';
            }

            $error_code = 0;
            $error_msg  = '';
            try
            {
                if ($username)
                {
                    $tmplink = new $mclass("mongodb://{$username}:{$password}@{$hostname}:{$port}/", $options);
                }
                else
                {
                    $tmplink = new $mclass("mongodb://{$hostname}:{$port}/", $options);
                }
            }
            catch (Exception $e)
            {
                $error_msg  = $e->getMessage();
                $error_code = $e->getCode();
                $tmplink    = false;
            }

            if (false===$tmplink)
            {
                if (IS_DEBUG)
                {
                    throw $e;
                }
                else
                {
                    $error_msg = 'connect mongodb server error.';
                }
                throw new Exception($error_msg, $error_code);
            }

            if (null!==$readpreference)
            {
                $tmplink->setReadPreference($readpreference);
            }

            Core::debug()->info('MongoDB '.($username?$username.'@':'').$hostname.':'.$port.' connection time:' . (microtime(true) - $time));

            # 连接ID
            $this->_connection_ids[$this->_connection_type] = $_connection_id;
            Database_Driver_Mongo::$_connection_instance[$_connection_id] = $tmplink;

            unset($tmplink);

            break;
        }
        catch (Exception $e)
        {
            if (IS_DEBUG)
            {
                Core::debug()->error(($username?$username.'@':'').$hostname.':'.$port, 'connect mongodb server error');
                $last_error = new Exception($e->getMessage(),$e->getCode());
            }
            else
            {
                $last_error = new Exception('connect mongodb server error', $e->getCode());
            }

            if (!in_array($hostname, $error_host))
            {
                $error_host[] = $hostname;
            }
        }
    }
}