Gio.BufferedInputStream::fill_async

function vfunc_fill_async(count: Number(gssize), io_priority: Number(gint), cancellable: Gio.Cancellable, callback: Gio.AsyncReadyCallback): void {
}
  

Reads data into stream's buffer asynchronously, up to count size. io_priority can be used to prioritize reads. For the synchronous version of this function, see Gio.BufferedInputStream.prototype.fill.

If count is -1 then the attempted read size is equal to the number of bytes that are required to fill the buffer.