Poco::StreamSocket: detect sending fail

Question

Lets say I have a message queue, e.g. std::deque<std::vector<uint8_t>>() I made a poll() (or select), and know that socket is ready for writing.

I do:

const auto& message = _messageQueue.front();
_socket.sendBytes(message.data(), message.size());
_messageQueue.pop_front();

For example, I can do an assertion that bytes sent is the same as message size, but Poco documentations says that StreamSocket::sendBytes()

Returns the number of bytes sent, which may be less than the number of bytes specified.

Poco documentation also does not say anything what actually setBlocking() method does. Does it blocks until ACK packet received, and throws on socket error?

Answer 1

example, I can do an assertion that bytes sent is the same as message size, but Poco documentations says that StreamSocket::sendBytes()

Returns the number of bytes sent, which may be less than the number of bytes specified.

This is only correct in non-blocking mode. In blocking mode, I t will transfer all the bytes before it returns, unless there is an error. This is defined by Posix, not by Poco. If there is an actual question here, I can't see it.

Poco documentation also does not say anything what actually setBlocking() method does. Does it blocks until ACK packet received?

No. It causes future reads to block until there is data or EOS or an error, and writes to blockuntil the data hasbeen copied into the socket send buffer.