SeekAheadOptimize Class — netty Architecture

Source Code

codec-http/src/main/java/io/netty/handler/codec/http/multipart/HttpPostBodyUtil.java lines 83–124

    static class SeekAheadOptimize {
        byte[] bytes;
        int readerIndex;
        int pos;
        int origPos;
        int limit;
        ByteBuf buffer;

        /**
         * @param buffer buffer with a backing byte array
         */
        SeekAheadOptimize(ByteBuf buffer) {
            if (!buffer.hasArray()) {
                throw new IllegalArgumentException("buffer hasn't backing byte array");
            }
            this.buffer = buffer;
            bytes = buffer.array();
            readerIndex = buffer.readerIndex();
            origPos = pos = buffer.arrayOffset() + readerIndex;
            limit = buffer.arrayOffset() + buffer.writerIndex();
        }

        /**
        *
        * @param minus this value will be used as (currentPos - minus) to set
        * the current readerIndex in the buffer.
        */
        void setReadPosition(int minus) {
            pos -= minus;
            readerIndex = getReadPosition(pos);
            buffer.readerIndex(readerIndex);
        }

        /**
        *
        * @param index raw index of the array (pos in general)
        * @return the value equivalent of raw index to be used in readerIndex(value)
        */
        int getReadPosition(int index) {
            return index - origPos + readerIndex;
        }
    }