RedisDecoder Class — netty Architecture

Source Code

codec-redis/src/main/java/io/netty/handler/codec/redis/RedisDecoder.java lines 34–332

@UnstableApi
public final class RedisDecoder extends ByteToMessageDecoder {

    private final ToPositiveLongProcessor toPositiveLongProcessor = new ToPositiveLongProcessor();

    private final boolean decodeInlineCommands;
    private final int maxInlineMessageLength;
    private final RedisMessagePool messagePool;

    // current decoding states
    private State state = State.DECODE_TYPE;
    private RedisMessageType type;
    private int remainingBulkLength;

    private enum State {
        DECODE_TYPE,
        DECODE_INLINE, // SIMPLE_STRING, ERROR, INTEGER
        DECODE_LENGTH, // BULK_STRING, ARRAY_HEADER
        DECODE_BULK_STRING_EOL,
        DECODE_BULK_STRING_CONTENT,
    }

    /**
     * Creates a new instance with default {@code maxInlineMessageLength} and {@code messagePool}
     * and inline command decoding disabled.
     */
    public RedisDecoder() {
        this(false);
    }

    /**
     * Creates a new instance with default {@code maxInlineMessageLength} and {@code messagePool}.
     * @param decodeInlineCommands if {@code true}, inline commands will be decoded.
     */
    public RedisDecoder(boolean decodeInlineCommands) {
        this(RedisConstants.REDIS_INLINE_MESSAGE_MAX_LENGTH, FixedRedisMessagePool.INSTANCE, decodeInlineCommands);
    }

    /**
     * Creates a new instance with inline command decoding disabled.
     * @param maxInlineMessageLength the maximum length of inline message.
     * @param messagePool the predefined message pool.
     */
    public RedisDecoder(int maxInlineMessageLength, RedisMessagePool messagePool) {
        this(maxInlineMessageLength, messagePool, false);
    }

    /**
     * Creates a new instance.
     * @param maxInlineMessageLength the maximum length of inline message.
     * @param messagePool the predefined message pool.
     * @param decodeInlineCommands if {@code true}, inline commands will be decoded.
     */
    public RedisDecoder(int maxInlineMessageLength, RedisMessagePool messagePool, boolean decodeInlineCommands) {
        if (maxInlineMessageLength <= 0 || maxInlineMessageLength > RedisConstants.REDIS_MESSAGE_MAX_LENGTH) {
            throw new RedisCodecException("maxInlineMessageLength: " + maxInlineMessageLength +
                                          " (expected: <= " + RedisConstants.REDIS_MESSAGE_MAX_LENGTH + ")");
        }
        this.maxInlineMessageLength = maxInlineMessageLength;
        this.messagePool = messagePool;
        this.decodeInlineCommands = decodeInlineCommands;
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        try {
            for (;;) {
                switch (state) {
                case DECODE_TYPE:
                    if (!decodeType(in)) {
                        return;
                    }
                    break;
                case DECODE_INLINE:
                    if (!decodeInline(in, out)) {
                        return;
                    }
                    break;
                case DECODE_LENGTH:
                    if (!decodeLength(in, out)) {
                        return;