Note that since this method never blocks, you cannot actually
use cancellable to cancel it. However, it will return an error
if cancellable has already been cancelled when you call, which
may happen if you call this method after a source triggers due
to having been cancelled.
Also note that if gio.types.IOErrorEnum.WouldBlock is returned some underlying
transports like D/TLS require that you re-send the same buffer and
count in the next write call.
Attempts to write up to count bytes from buffer to stream, as with gio.output_stream.OutputStream.write. If stream is not currently writable, this will immediately return gio.types.IOErrorEnum.WouldBlock, and you can use gio.pollable_output_stream.PollableOutputStream.createSource to create a #GSource that will be triggered when stream is writable.
Note that since this method never blocks, you cannot actually use cancellable to cancel it. However, it will return an error if cancellable has already been cancelled when you call, which may happen if you call this method after a source triggers due to having been cancelled.
Also note that if gio.types.IOErrorEnum.WouldBlock is returned some underlying transports like D/TLS require that you re-send the same buffer and count in the next write call.
The behaviour of this method is undefined if gio.pollable_output_stream.PollableOutputStream.canPoll returns false for stream.