Reads data into this's buffer asynchronously, up to count size.
io_priority can be used to prioritize reads. For the synchronous version of this function, see [
method@Gio.BufferedInputStream.fill].
If count is `-1` then the attempted read size is equal to the number of bytes that are required to fill the buffer.
| this |
a [class@Gio.BufferedInputStream] |
| count |
the number of bytes that will be read from the stream |
| io_priority |
the [I/O priority](iface.AsyncResult.html#io-priority) of the request |
| cancellable |
optional [class@Gio.Cancellable] object |
| callback |
a [callback@Gio.AsyncReadyCallback] |
| user_data |
a pointer |