A #GstPoll keeps track of file descriptors much like fd_set (used with select()) or a struct pollfd array (used with poll()). Once created with gst_poll_new(), the set can be used to wait for file descriptors to be readable and/or writable. It is possible to make this wait be controlled by specifying %TRUE for the @controllable flag when creating the set (or later calling gst_poll_set_controllable()).