protected void encodeResponse()

in dubbo-remoting/dubbo-remoting-api/src/main/java/org/apache/dubbo/remoting/exchange/codec/ExchangeCodec.java [310:427]
100 lines of code
16 McCabe index (conditional complexity)

    protected void encodeResponse(Channel channel, ChannelBuffer buffer, Response res) throws IOException {
        int savedWriteIndex = buffer.writerIndex();
        try {
            Serialization serialization = getSerialization(channel, res);
            // header.
            byte[] header = new byte[HEADER_LENGTH];
            // set magic number.
            Bytes.short2bytes(MAGIC, header);
            // set request and serialization flag.
            header[2] = serialization.getContentTypeId();
            if (res.isHeartbeat()) {
                header[2] |= FLAG_EVENT;
            }
            // set response status.
            byte status = res.getStatus();
            header[3] = status;
            // set request id.
            Bytes.long2bytes(res.getId(), header, 4);

            buffer.writerIndex(savedWriteIndex + HEADER_LENGTH);
            ChannelBufferOutputStream bos = new ChannelBufferOutputStream(buffer);

            // encode response data or error message.
            if (status == Response.OK) {
                if (res.isHeartbeat()) {
                    // heartbeat response data is always null
                    bos.write(CodecSupport.getNullBytesOf(serialization));
                } else {
                    ObjectOutput out = serialization.serialize(channel.getUrl(), bos);
                    if (res.isEvent()) {
                        encodeEventData(channel, out, res.getResult());
                    } else {
                        encodeResponseData(channel, out, res.getResult(), res.getVersion());
                    }
                    out.flushBuffer();
                    if (out instanceof Cleanable) {
                        ((Cleanable) out).cleanup();
                    }
                }
            } else {
                ObjectOutput out = serialization.serialize(channel.getUrl(), bos);
                out.writeUTF(res.getErrorMessage());
                out.flushBuffer();
                if (out instanceof Cleanable) {
                    ((Cleanable) out).cleanup();
                }
            }

            bos.flush();
            bos.close();

            int len = bos.writtenBytes();
            checkPayload(channel, len);
            Bytes.int2bytes(len, header, 12);
            // write
            buffer.writerIndex(savedWriteIndex);
            buffer.writeBytes(header); // write header.
            buffer.writerIndex(savedWriteIndex + HEADER_LENGTH + len);
        } catch (Throwable t) {
            // clear buffer
            buffer.writerIndex(savedWriteIndex);
            // send error message to Consumer, otherwise, Consumer will wait till timeout.
            if (!res.isEvent() && res.getStatus() != Response.BAD_RESPONSE) {
                Response r = new Response(res.getId(), res.getVersion());
                r.setStatus(Response.BAD_RESPONSE);

                if (t instanceof ExceedPayloadLimitException) {
                    logger.warn(TRANSPORT_EXCEED_PAYLOAD_LIMIT, "", "", t.getMessage(), t);
                    try {
                        r.setErrorMessage(t.getMessage());
                        r.setStatus(Response.SERIALIZATION_ERROR);
                        channel.send(r);
                        return;
                    } catch (RemotingException e) {
                        logger.warn(
                                TRANSPORT_FAILED_RESPONSE,
                                "",
                                "",
                                "Failed to send bad_response info back: " + t.getMessage() + ", cause: "
                                        + e.getMessage(),
                                e);
                    }
                } else {
                    // FIXME log error message in Codec and handle in caught() of IoHanndler?
                    logger.warn(
                            TRANSPORT_FAILED_RESPONSE,
                            "",
                            "",
                            "Fail to encode response: " + res + ", send bad_response info instead, cause: "
                                    + t.getMessage(),
                            t);
                    try {
                        r.setErrorMessage("Failed to send response: " + res + ", cause: " + StringUtils.toString(t));
                        channel.send(r);
                        return;
                    } catch (RemotingException e) {
                        logger.warn(
                                TRANSPORT_FAILED_RESPONSE,
                                "",
                                "",
                                "Failed to send bad_response info back: " + res + ", cause: " + e.getMessage(),
                                e);
                    }
                }
            }

            // Rethrow exception
            if (t instanceof IOException) {
                throw (IOException) t;
            } else if (t instanceof RuntimeException) {
                throw (RuntimeException) t;
            } else if (t instanceof Error) {
                throw (Error) t;
            } else {
                throw new RuntimeException(t.getMessage(), t);
            }
        }
    }