@deftypefun {void} {gnutls_transport_set_vec_push_function} (gnutls_session_t @var{session}, gnutls_vec_push_func @var{vec_func})
@var{session}: is a @code{gnutls_session_t}  type.

@var{vec_func}: a callback function similar to @code{writev()} 

Using this function you can override the default writev(2)
function for gnutls to send data. Setting this callback 
instead of @code{gnutls_transport_set_push_function()}  is recommended
since it introduces less overhead in the TLS handshake process.

 @code{vec_func} is of the form,
ssize_t (*gnutls_vec_push_func) (gnutls_transport_ptr_t, const giovec_t * iov, int iovcnt);

@strong{Since:} 2.12.0
@end deftypefun