* Creates a key for the specified request for response matching.
     *
     * @param request the request to create a key for
     * @throws IOException if an I/O error occurs
     */
    protected abstract void makeKey(Request request) throws IOException;

    /**
     * Reads and returns the key of the next message without consuming it.
     *
     * @return the request key of the next message

            socket.close();
        } finally {
            digest = null;
            socket = null;
            tconHostName = null;
        }
    }

    @Override
    protected void makeKey(final Request request) throws IOException {
        /* The request *is* the key */
        if (++mid == 32000) {
            mid = 1;
        }
        ((ServerMessageBlock) request).mid = mid;
    }

        private IOException recvException = null;
        private boolean connectFails = false;
        private boolean disconnectResult = false;

        @Override
        protected long makeKey(Request request) throws IOException {
            return nextKey++;
        }

        @Override
        protected Long peekKey() throws IOException {
            if (recvException != null) {

     *
     * @param request the request to generate a key for
     * @return the generated key
     * @throws IOException if an I/O error occurs
     */
    protected abstract long makeKey(Request request) throws IOException;

    /**
     * Peek at the next key without removing it from the input stream
     *
     * @return the next key or null if none available

    /**
     * @return
     * @throws IOException
     */
    private int negotiateWrite(final CommonServerMessageBlockRequest req, final boolean setmid) throws IOException {
        if (setmid) {
            makeKey(req);
        } else {
            req.setMid(0);
            this.mid.set(1);
        }
        final int n = req.encode(this.sbuf, 4);

                Arguments.of(makeSeq(8), 0, 8, 0), // full copy at index 0
                Arguments.of(makeSeq(10), 2, 5, 3), // middle slice, non-zero dst index
                Arguments.of(makeSeq(4), 4, 0, 0), // zero-length slice at end
                Arguments.of(makeSeq(16), 7, 3, 0), // small slice from middle
                Arguments.of(makeSeq(16), 0, 0, 5) // zero-length with non-zero dst index
        );