Gio-2.0 ▶ Gio ▶ PollableOutputStream ▶ Interface

Checks if stream is actually pollable. Some classes may implement Gio.PollableOutputStream but have only certain instances of that class be pollable. If this method returns false, then the behavior of other Gio.PollableOutputStream methods is undefined.

For any given stream, the value returned by this method is constant; a stream cannot switch from pollable to non-pollable or vice versa.

Creates a GLib.Source that triggers when stream can be written, or cancellable is triggered or an error occurs. The callback on the source is of the Gio.PollableSourceFunc type.

As with g_pollable_output_stream_is_writable(), it is possible that the stream may not actually be writable even after the source triggers, so you should use g_pollable_output_stream_write_nonblocking() rather than g_output_stream_write() from the callback.

The behaviour of this method is undefined if g_pollable_output_stream_can_poll() returns false for stream.

Checks if stream can be written.

Note that some stream types may not be able to implement this 100% reliably, and it is possible that a call to g_output_stream_write() after this returns true would still block. To guarantee non-blocking behavior, you should always use g_pollable_output_stream_write_nonblocking(), which will return a Gio.IOErrorEnum.WOULD_BLOCK error rather than blocking.

The behaviour of this method is undefined if g_pollable_output_stream_can_poll() returns false for stream.

Attempts to write up to count bytes from buffer to stream, as with g_output_stream_write(). If stream is not currently writable, this will immediately return Gio.IOErrorEnum.WOULD_BLOCK, and you can use g_pollable_output_stream_create_source() to create a GLib.Source 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.IOErrorEnum.WOULD_BLOCK 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 g_pollable_output_stream_can_poll() returns false for stream.

Attempts to write the bytes contained in the n_vectors vectors to stream, as with g_output_stream_writev(). If stream is not currently writable, this will immediately return %G_POLLABLE_RETURN_WOULD_BLOCK, and you can use g_pollable_output_stream_create_source() to create a GLib.Source that will be triggered when stream is writable. error will not be set in that case.

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.PollableReturn.WOULD_BLOCK is returned some underlying transports like D/TLS require that you re-send the same vectors and n_vectors in the next write call.

The behaviour of this method is undefined if g_pollable_output_stream_can_poll() returns false for stream.