decode() — netty Function Reference

Architecture documentation for the decode() function in FastLzFrameDecoder.java from the netty codebase.

Function java Buffer Allocators

Entity Profile

Buffer→ Allocators→ decode() — netty Function Reference

Dependency Diagram

graph TD
  0eec1c5c_5152_4314_9a45_92a187fc7c63["decode()"]
  027237ff_2dd9_ddc6_a78e_256023cb6517["FastLzFrameDecoder"]
  0eec1c5c_5152_4314_9a45_92a187fc7c63 -->|defined in| 027237ff_2dd9_ddc6_a78e_256023cb6517
  style 0eec1c5c_5152_4314_9a45_92a187fc7c63 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

codec-compression/src/main/java/io/netty/handler/codec/compression/FastLzFrameDecoder.java lines 112–207

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        try {
            switch (currentState) {
            case INIT_BLOCK:
                if (in.readableBytes() < 4) {
                    break;
                }

                final int magic = in.readUnsignedMedium();
                if (magic != MAGIC_NUMBER) {
                    throw new DecompressionException("unexpected block identifier");
                }

                final byte options = in.readByte();
                isCompressed = (options & 0x01) == BLOCK_TYPE_COMPRESSED;
                hasChecksum = (options & 0x10) == BLOCK_WITH_CHECKSUM;

                currentState = State.INIT_BLOCK_PARAMS;
                // fall through
            case INIT_BLOCK_PARAMS:
                if (in.readableBytes() < 2 + (isCompressed ? 2 : 0) + (hasChecksum ? 4 : 0)) {
                    break;
                }
                currentChecksum = hasChecksum ? in.readInt() : 0;
                chunkLength = in.readUnsignedShort();
                originalLength = isCompressed ? in.readUnsignedShort() : chunkLength;

                currentState = State.DECOMPRESS_DATA;
                // fall through
            case DECOMPRESS_DATA:
                final int chunkLength = this.chunkLength;
                if (in.readableBytes() < chunkLength) {
                    break;
                }

                final int idx = in.readerIndex();
                final int originalLength = this.originalLength;

                ByteBuf output = null;

                try {
                    if (isCompressed) {

                        output = ctx.alloc().buffer(originalLength);
                        int outputOffset = output.writerIndex();
                        final int decompressedBytes = decompress(in, idx, chunkLength,
                                output, outputOffset, originalLength);
                        if (originalLength != decompressedBytes) {
                            throw new DecompressionException(String.format(
                                    "stream corrupted: originalLength(%d) and actual length(%d) mismatch",
                                    originalLength, decompressedBytes));
                        }
                        output.writerIndex(output.writerIndex() + decompressedBytes);
                    } else {
                        output = in.retainedSlice(idx, chunkLength);
                    }

                    final ByteBufChecksum checksum = this.checksum;
                    if (hasChecksum && checksum != null) {
                        checksum.reset();
                        checksum.update(output, output.readerIndex(), output.readableBytes());
                        final int checksumResult = (int) checksum.getValue();
                        if (checksumResult != currentChecksum) {
                            throw new DecompressionException(String.format(
                                    "stream corrupted: mismatching checksum: %d (expected: %d)",
                                    checksumResult, currentChecksum));
                        }
                    }

                    if (output.readableBytes() > 0) {
                        out.add(output);
                    } else {
                        output.release();
                    }
                    output = null;
                    in.skipBytes(chunkLength);

                    currentState = State.INIT_BLOCK;
                } finally {
                    if (output != null) {