Re: [Boost-users] [ASIO] Streambuf not containing full line

On 27/02/2014 08:55, Quoth Gonzalo Garramuno:

I am using asio asynchronically. I have:

void tcp_session::start_read() { // Set a deadline for the read operation.

// input_deadline_.expires_from_now(boost::posix_time::seconds(30)); // input_deadline_.expires_at(boost::posix_time::pos_infin);

// Start an asynchronous operation to read a newline-delimited message. boost::asio::async_read_until(socket(), input_buffer_, '\n', boost::bind(&tcp_session::handle_read, shared_from_this(), boost::asio::placeholders::error)); }

Are you using the same (unmodified) buffer each time? async_read_until will pull more than a single line of data into the given buffer and expects the remaining data to remain in there for the next call.

std::string msg; std::istream is(&input_buffer_); is.exceptions( std::ifstream::failbit | std::ifstream::badbit | std::ifstream::eofbit );

try { while ( std::getline(is, msg) )

This is the wrong way to do it. This will eat more than the one line "officially" returned from the read call, including the still-being-received data at the end. It's also a waste of time to call "getline" again because you're just going to make it search for a newline that has already been found by async_read_until. A better way to do it is to include boost::asio::placeholders::bytes_transferred in your handler callback (as the "size" parameter), which then lets you simply: std::string line(boost::asio::buffer_cast(input_buffer_.data()), size); input_buffer_.consume(size); (I believe this leaves the delimiter at the end though, so you might want to trim that off from your line too; but don't forget to still consume it.) Don't call it in a loop; just do it once and then issue the async_read_until again. This will complete immediately if the buffer already contains another line. A bit more complexity is required if you are mixing both async_read and async_read_until calls on the same socket.