org.apache.lucene.util.packed

Class MonotonicBlockPackedWriter

java.lang.Object

org.apache.lucene.util.packed.AbstractBlockPackedWriter

org.apache.lucene.util.packed.MonotonicBlockPackedWriter

public final class MonotonicBlockPackedWriter
extends AbstractBlockPackedWriter

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.

Format:

• <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:

MonotonicBlockPackedReader

Field Summary

Fields inherited from class org.apache.lucene.util.packed.AbstractBlockPackedWriter

blocks, BPV_SHIFT, finished, MAX_BLOCK_SIZE, MIN_BLOCK_SIZE, MIN_VALUE_EQUALS_0, off, ord, out, values

Constructor Summary

Constructors

Constructor and Description
MonotonicBlockPackedWriter(DataOutput out, int blockSize) Sole constructor.

Method Summary

Modifier and Type	Method and Description
void	add(long l) Append a new long.
protected void	flush()

Methods inherited from class org.apache.lucene.util.packed.AbstractBlockPackedWriter

addBlockOfZeros, finish, ord, reset, writeValues, writeVLong

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MonotonicBlockPackedWriter

public MonotonicBlockPackedWriter(DataOutput out,
                                  int blockSize)

Sole constructor.

Parameters:

blockSize - the number of values of a single block, must be a power of 2

Method Detail

add

public void add(long l)
         throws java.io.IOException

Description copied from class: AbstractBlockPackedWriter

Append a new long.

Overrides:

add in class AbstractBlockPackedWriter

Throws:

java.io.IOException

flush

protected void flush()
              throws java.io.IOException

Specified by:

flush in class AbstractBlockPackedWriter

Throws:

java.io.IOException