receive_messages

Receive multiple data messages from this in one go.

This is the most complicated and fully-featured version of this call. For easier use, see receive, receive_from, and receive_message.

messages must point to an array of InputMessage structs and messages.length must be the length of this array. Each InputMessage contains a pointer to an array of InputVector structs describing the buffers that the data received in each message will be written to. Using multiple InputVectors is more memory-efficient than manually copying data out of a single buffer to multiple sources, and more system-call-efficient than making multiple calls to receive, such as in scenarios where a lot of data packets need to be received (e.g. high-bandwidth video streaming over RTP/UDP).

flags modify how all messages are received. The commonly available arguments for this are available in the SocketMsgFlags enum, but the values there are the same as the system values, and the flags are passed in as-is, so you can pass in system-specific flags too. These flags affect the overall receive operation. Flags affecting individual messages are returned in flags.

The other members of InputMessage are treated as described in its documentation.

If blocking is true the call will block until messages.length have been received, or the end of the stream is reached.

If blocking is false the call will return up to messages.length without blocking, or g_io_error_would_block if no messages are queued in the operating system to be received.

In blocking mode, if timeout is positive and is reached before any messages are received, g_io_error_timed_out is returned, otherwise up to messages.length are returned. ( Note: This is effectively the behaviour of `MSG_WAITFORONE` with recvmmsg.)

To be notified when messages are available, wait for the g_io_in condition. Note though that you may still receive g_io_error_would_block from receive_messages even if you were previously notified of a g_io_in condition.

If the remote peer closes the connection, any messages queued in the operating system will be returned, and subsequent calls to receive_messages will return 0 (with no error set).

On error -1 is returned and throws is set accordingly. An error will only be returned if zero messages could be received; otherwise the number of messages successfully received before the error will be returned.

Parameters:

this	a Socket
messages	an array of InputMessage structs
flags	an int containing SocketMsgFlags flags for the overall operation, which may additionally contain other platform specific flags
cancellable	a gcancellable or null
num_messages	the number of elements in messages

Returns:

number of messages received, or -1 on error. Note that the number of messages received may be smaller than messages.length if in non-blocking mode, if the peer closed the connection, or if messages.length was larger than `UIO_MAXIOV` (1024), in which case the caller may re-try to receive the remaining messages.