BlockPackedWriter (Jackrabbit Oak 1.71-SNAPSHOT API)

java.lang.Object
- org.apache.lucene.util.packed.BlockPackedWriter

```
public final class BlockPackedWriter
extends Object
```
A writer for large sequences of longs.
The sequence is divided into fixed-size blocks and for each block, the difference between each value and the minimum value of the block is encoded using as few bits as possible. Memory usage of this class is proportional to the block size. Each block has an overhead between 1 and 10 bytes to store the minimum value and the number of bits per value of the block.
Format:
- <BLock>^BlockCount
- BlockCount: ⌈ ValueCount / BlockSize ⌉
- Block: <Header, (Ints)>
- Header: <Token, (MinValue)>
- Token: a byte, first 7 bits are the number of bits per value (bitsPerValue). If the 8th bit is 1, then MinValue (see next) is 0, otherwise MinValue and needs to be decoded
- MinValue: a zigzag-encoded variable-length long whose value should be added to every int from the block to restore the original values
- Ints: If the number of bits per value is 0, then there is nothing to decode and all ints are equal to MinValue. Otherwise: BlockSize packed ints encoded on exactly bitsPerValue bits per value. They are the subtraction of the original values and MinValue
See Also:

BlockPackedReaderIterator, BlockPackedReader

Field Summary

Fields
Modifier and Type	Field	Description
`protected byte[]`	`blocks`
`protected boolean`	`finished`
`protected int`	`off`
`protected long`	`ord`
`protected DataOutput`	`out`
`protected long[]`	`values`

Constructor Summary

Constructors
Constructor Description

BlockPackedWriter(DataOutput out, int blockSize)
Sole constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`add(long l)`	Append a new long.
`void`	`finish()`	Flush all buffered data to disk.
`protected void`	`flush()`
`long`	`ord()`	Return the number of values which have been added.
`void`	`reset(DataOutput out)`	Reset this writer to wrap `out`.
`protected void`	`writeValues(int bitsRequired)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - out
```
protected DataOutput out
```
  - values
```
protected final long[] values
```
  - blocks
```
protected byte[] blocks
```
  - off
```
protected int off
```
  - ord
```
protected long ord
```
  - finished
```
protected boolean finished
```
- Constructor Detail
  - BlockPackedWriter
```
public BlockPackedWriter(DataOutput out,
                         int blockSize)
```
    Sole constructor.
    
    Parameters:
    
    blockSize - the number of values of a single block, must be a power of 2
- Method Detail
  - flush
```
protected void flush()
              throws IOException
```
    Throws:
    
    IOException
  - reset
```
public void reset(DataOutput out)
```
    Reset this writer to wrap out. The block size remains unchanged.
  - add
```
public void add(long l)
         throws IOException
```
    Append a new long.
    
    Throws:
    
    IOException
  - 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.
    
    Throws:
    
    IOException
  - ord
```
public long ord()
```
    Return the number of values which have been added.
  - writeValues
```
protected final void writeValues(int bitsRequired)
                          throws IOException
```
    Throws:
    
    IOException