Method read

utils/src/main/java/com/cloud/utils/nio/Link.java:181–287

(SocketChannel ch)

    protected static final int HEADER_FLAG_FOLLOWING = 0x10000;

    public byte[] read(SocketChannel ch) throws IOException {
        if (_readHeader) {   // Start of a packet
            if (_readBuffer.position() == 0) {
                _readBuffer.limit(4);
            }

            if (ch.read(_readBuffer) == -1) {
                throw new IOException("Connection closed with -1 on reading size.");
            }

            if (_readBuffer.hasRemaining()) {
                LOGGER.trace("Need to read the rest of the packet length");
                return null;
            }
            _readBuffer.flip();
            int header = _readBuffer.getInt();
            int readSize = (short)header;
            if (LOGGER.isTraceEnabled()) {
                LOGGER.trace("Packet length is " + readSize);
            }

            if (readSize > MAX_SIZE_PER_PACKET) {
                throw new IOException("Wrong packet size: " + readSize);
            }

            if (!_gotFollowingPacket) {
                _plaintextBuffer = ByteBuffer.allocate(2000);
            }

            if ((header & HEADER_FLAG_FOLLOWING) != 0) {
                _gotFollowingPacket = true;
            } else {
                _gotFollowingPacket = false;
            }

            _readBuffer.clear();
            _readHeader = false;

            if (_readBuffer.capacity() < readSize) {
                if (LOGGER.isTraceEnabled()) {
                    LOGGER.trace("Resizing the byte buffer from " + _readBuffer.capacity());
                }
                _readBuffer = ByteBuffer.allocate(readSize);
            }
            _readBuffer.limit(readSize);
        }

        if (ch.read(_readBuffer) == -1) {
            throw new IOException("Connection closed with -1 on read.");
        }

        if (_readBuffer.hasRemaining()) {   // We're not done yet.
            if (LOGGER.isTraceEnabled()) {
                LOGGER.trace("Still has " + _readBuffer.remaining());
            }
            return null;
        }