writeBytesAsync
This function is similar to g_output_stream_write_async(), but takes a #GBytes as input. Due to the refcounted nature of #GBytes, this allows the stream to avoid taking a copy of the data.
However, note that this function may still perform partial writes, just like g_output_stream_write_async(). If that occurs, to continue writing, you will need to create a new #GBytes containing just the remaining bytes, using g_bytes_new_from_bytes(). Passing the same #GBytes instance multiple times potentially can result in duplicated data in the output stream.
For the synchronous, blocking version of this function, see g_output_stream_write_bytes().
Parameters
The bytes to write
the io priority of the request.
optional #GCancellable object, null to ignore.
callback to call when the request is satisfied