Class MonotonicBlockPackedWriter

  • public final class MonotonicBlockPackedWriter
    extends Object
    A writer for large monotonically increasing sequences of positive longs.

    The sequence is divided into fixed-size blocks and for each block, values are modeled after a linear function f: x → A × x + B. The block encodes deltas from the expected values computed from this function using as few bits as possible.


    • <BLock>BlockCount
    • BlockCount: ⌈ ValueCount / BlockSize ⌉
    • Block: <Header, (Ints)>
    • Header: <B, A, BitsPerValue>
    • B: the B from f: x → A × x + B using a zig-zag encoded vLong
    • A: the A from f: x → A × x + B encoded using Float.floatToIntBits(float) on 4 bytes
    • BitsPerValue: a variable-length int
    • Ints: if BitsPerValue is 0, then there is nothing to read and all values perfectly match the result of the function. Otherwise, these are the packed deltas from the expected value (computed from the function) using exactly BitsPerValue bits per value.
    See Also:
    NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.
    • Field Detail

      • values

        protected final long[] values
      • blocks

        protected byte[] blocks
      • off

        protected int off
      • ord

        protected long ord
      • finished

        protected boolean finished
    • Constructor Detail

      • MonotonicBlockPackedWriter

        public MonotonicBlockPackedWriter​(DataOutput out,
                                          int blockSize)
        Sole constructor.
        blockSize - the number of values of a single block, must be a power of 2
    • Method Detail

      • reset

        public void reset​(DataOutput out)
        Reset this writer to wrap out. The block size remains unchanged.
      • finish

        public void finish()
                    throws IOException
        Flush all buffered data to disk. This instance is not usable anymore after this method has been called until reset(DataOutput) has been called.
      • ord

        public long ord()
        Return the number of values which have been added.