(PECL event >= 1.7.0)
EventUtil::getSocketFd — Returns numeric file descriptor of a socket, or stream
   Returns numeric file descriptor of a socket or stream specified by
   socket
   argument just like the
   Event
   extension does it internally for all methods accepting socket resource or
   stream.
  
socket
    Socket resource or stream.
   Returns numeric file descriptor of a socket, or stream.
   EventUtil::getSocketFd()
   returns FALSE in case if it is whether failed to recognize the type of
   the underlying file, or detected that the file descriptor associated with
   socket
   is not valid.