public function getEtag($visitor_identifier, $use_cache = true)
    {
        $timestamp_field = $this->getTimestampField();

        if ($timestamp_field && ($this->tag === false || !$use_cache)) {
            $this->tag = $this->prepareTagFromBits($this->getAdditionalIdentifier(), $visitor_identifier, $this->getTimestampHash($timestamp_field));
        }

        return $this->tag;
    }
public function getEtag($visitor_identifier, $use_cache = true)
    {
        $timestamp_field = $this->getTimestampField();

        if ($timestamp_field && ($this->tag === false || !$use_cache)) {
            $this->tag = $this->prepareTagFromBits($this->getAdditionalIdentifier(), $visitor_identifier, $this->getTimestampHash($timestamp_field));
        }

        return $this->tag;
    }
public function getEtag ( $ visitor_identifier , $ use_cache = true ) { $ timestamp_field = $ this -> getTimestampField ( ) ; if ( $ timestamp_field && ( $ this -> tag === false || ! $ use_cache ) ) { $ this -> tag = $ this -> prepareTagFromBits ( $ this -> getAdditionalIdentifier ( ) , $ visitor_identifier , $ this -> getTimestampHash ( $ timestamp_field ) ) ; } return $ this -> tag ; }
Return collection etag.

@param  string $visitor_identifier
@param  bool   $use_cache
@return string
Return collection etag .