/**
* Returns the singleton instance of the Tracer.
*
* For convenience, this function can be passed the $component_name and
* $access_token parameters to also initialize the tracer singleton. These
* values will be ignored on any calls after the first to getInstance().
*
* @param $component_name Component name to use for the tracer
* @param $access_token The project access token
* @return \LightStepBase\Tracer
* @throws Exception if the group name or access token is not a valid string
*/
public static function getInstance($component_name = NULL, $access_token = NULL, $opts = NULL)
{
if (!isset(self::$_singleton)) {
self::$_singleton = self::newTracer($component_name, $access_token, $opts);
}
return self::$_singleton;
}
