Method socketReceiveBytesImpl

src/IO/ReadBufferFromPocoSocket.cpp:36–101

}

ssize_t ReadBufferFromPocoSocketBase::socketReceiveBytesImpl(char * ptr, size_t size)
{
    ssize_t bytes_read = 0;
    Stopwatch watch;

    SCOPE_EXIT({
        /// NOTE: it is quite inaccurate on high loads since the thread could be replaced by another one
        ProfileEvents::increment(ProfileEvents::NetworkReceiveElapsedMicroseconds, watch.elapsedMicroseconds());
        ProfileEvents::increment(ProfileEvents::NetworkReceiveBytes, bytes_read);
    });

    CurrentMetrics::Increment metric_increment(CurrentMetrics::NetworkReceive);

    /// Add more details to exceptions.
    try
    {
        /// If async_callback is specified, set socket to non-blocking mode
        /// and try to read data from it, if socket is not ready for reading,
        /// run async_callback and try again later.
        /// It is expected that file descriptor may be polled externally.
        /// Note that send timeout is not checked here. External code should check it while polling.
        if (async_callback)
        {
            socket.setBlocking(false);
            SCOPE_EXIT_SAFE(socket.setBlocking(true));
            bool secure = socket.secure();
            bytes_read = socket.impl()->receiveBytes(ptr, static_cast<int>(size));

            /// Check EAGAIN and ERR_SSL_WANT_READ/ERR_SSL_WANT_WRITE for secure socket (reading from secure socket can write too).
            while (bytes_read < 0 && (errno == EAGAIN || (secure && (checkSSLWantRead(bytes_read) || checkSSLWantWrite(bytes_read)))))
            {
                /// In case of ERR_SSL_WANT_WRITE we should wait for socket to be ready for writing, otherwise - for reading.
                if (secure && checkSSLWantWrite(bytes_read))
                    async_callback(socket.impl()->sockfd(), socket.getSendTimeout(), AsyncEventTimeoutType::SEND, socket_description, AsyncTaskExecutor::Event::WRITE | AsyncTaskExecutor::Event::ERROR);
                else
                    async_callback(socket.impl()->sockfd(), socket.getReceiveTimeout(), AsyncEventTimeoutType::RECEIVE, socket_description, AsyncTaskExecutor::Event::READ | AsyncTaskExecutor::Event::ERROR);

                /// Try to read again.
                bytes_read = socket.impl()->receiveBytes(ptr, static_cast<int>(size));
            }
        }
        else
        {
            bytes_read = socket.impl()->receiveBytes(ptr, static_cast<int>(size));
        }
    }
    catch (const Poco::Net::NetException & e)
    {
        throw NetException(ErrorCodes::NETWORK_ERROR, "{}, while reading from socket (peer: {}, local: {})", e.displayText(), peer_address.toString(), socket.address().toString());
    }
    catch (const Poco::TimeoutException &)
    {
        throw NetException(ErrorCodes::SOCKET_TIMEOUT, "Timeout exceeded while reading from socket (peer: {}, local: {}, {} ms)",
            peer_address.toString(), socket.address().toString(),
            socket.impl()->getReceiveTimeout().totalMilliseconds());
    }
    catch (const Poco::IOException & e)
    {