FastLzFrameDecoder Class — netty Architecture

Source Code

codec-compression/src/main/java/io/netty/handler/codec/compression/FastLzFrameDecoder.java lines 36–208

public class FastLzFrameDecoder extends ByteToMessageDecoder {
    /**
     * Current state of decompression.
     */
    private enum State {
        INIT_BLOCK,
        INIT_BLOCK_PARAMS,
        DECOMPRESS_DATA,
        CORRUPTED
    }

    private State currentState = State.INIT_BLOCK;

    /**
     * Underlying checksum calculator in use.
     */
    private final ByteBufChecksum checksum;

    /**
     * Length of current received chunk of data.
     */
    private int chunkLength;

    /**
     * Original of current received chunk of data.
     * It is equal to {@link #chunkLength} for non compressed chunks.
     */
    private int originalLength;

    /**
     * Indicates is this chunk compressed or not.
     */
    private boolean isCompressed;

    /**
     * Indicates is this chunk has checksum or not.
     */
    private boolean hasChecksum;

    /**
     * Checksum value of current received chunk of data which has checksum.
     */
    private int currentChecksum;

    /**
     * Creates the fastest FastLZ decoder without checksum calculation.
     */
    public FastLzFrameDecoder() {
        this(false);
    }

    /**
     * Creates a FastLZ decoder with calculation of checksums as specified.
     *
     * @param validateChecksums
     *        If true, the checksum field will be validated against the actual
     *        uncompressed data, and if the checksums do not match, a suitable
     *        {@link DecompressionException} will be thrown.
     *        Note, that in this case decoder will use {@link java.util.zip.Adler32}
     *        as a default checksum calculator.
     */
    public FastLzFrameDecoder(boolean validateChecksums) {
        this(validateChecksums ? new Adler32() : null);
    }

    /**
     * Creates a FastLZ decoder with specified checksum calculator.
     *
     * @param checksum
     *        the {@link Checksum} instance to use to check data for integrity.
     *        You may set {@code null} if you do not want to validate checksum of each block.
     */
    public FastLzFrameDecoder(Checksum checksum) {
        this.checksum = checksum == null ? null : ByteBufChecksum.wrapChecksum(checksum);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        try {
            switch (currentState) {
            case INIT_BLOCK: