ReplayingDecoder Class — netty Architecture

Source Code

codec-base/src/main/java/io/netty/handler/codec/ReplayingDecoder.java lines 268–424

public abstract class ReplayingDecoder<S> extends ByteToMessageDecoder {

    static final Signal REPLAY = Signal.valueOf(ReplayingDecoder.class, "REPLAY");

    private final ReplayingDecoderByteBuf replayable = new ReplayingDecoderByteBuf();
    private S state;
    private int checkpoint = -1;

    /**
     * Creates a new instance with no initial state (i.e: {@code null}).
     */
    protected ReplayingDecoder() {
        this(null);
    }

    /**
     * Creates a new instance with the specified initial state.
     */
    protected ReplayingDecoder(S initialState) {
        state = initialState;
    }

    /**
     * Stores the internal cumulative buffer's reader position.
     */
    protected void checkpoint() {
        checkpoint = internalBuffer().readerIndex();
    }

    /**
     * Stores the internal cumulative buffer's reader position and updates
     * the current decoder state.
     */
    protected void checkpoint(S state) {
        checkpoint();
        state(state);
    }

    /**
     * Returns the current state of this decoder.
     * @return the current state of this decoder
     */
    protected S state() {
        return state;
    }

    /**
     * Sets the current state of this decoder.
     * @return the old state of this decoder
     */
    protected S state(S newState) {
        S oldState = state;
        state = newState;
        return oldState;
    }

    @Override
    final void channelInputClosed(ChannelHandlerContext ctx, List<Object> out) throws Exception {
        try {
            replayable.terminate();
            if (cumulation != null) {
                callDecode(ctx, internalBuffer(), out);
            } else {
                replayable.setCumulation(Unpooled.EMPTY_BUFFER);
            }
            decodeLast(ctx, replayable, out);
        } catch (Signal replay) {
            // Ignore
            replay.expect(REPLAY);
        }
    }

    @Override
    protected void callDecode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
        replayable.setCumulation(in);
        try {
            while (in.isReadable()) {
                int oldReaderIndex = checkpoint = in.readerIndex();
                int outSize = out.size();

                if (outSize > 0) {