WALCellCodec (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.regionserver.wal.WALCellCodec

All Implemented Interfaces:

Codec

Direct Known Subclasses:

SecureWALCellCodec
```
@InterfaceAudience.LimitedPrivate(value={"Coprocesssor","Phoenix","Configuration"})
public class WALCellCodec
extends Object
implements Codec
```
Compression in this class is lifted off Compressor/KeyValueCompression. This is a pure coincidence... they are independent and don't have to be compatible. This codec is used at server side for writing cells to WAL as well as for sending edits as part of the distributed splitting process.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`(package private) static class`	`WALCellCodec.BaosAndCompressor`
`static interface`	`WALCellCodec.ByteStringCompressor`
`static interface`	`WALCellCodec.ByteStringUncompressor`
`(package private) static class`	`WALCellCodec.CompressedKvDecoder`
`(package private) static class`	`WALCellCodec.CompressedKvEncoder`
`static class`	`WALCellCodec.EnsureKvEncoder`

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.codec.Codec
Codec.Decoder, Codec.Encoder

Field Summary

Fields
Modifier and Type	Field and Description
`protected CompressionContext`	`compression`
`protected WALCellCodec.ByteStringUncompressor`	`statelessUncompressor`
`static String`	`WAL_CELL_CODEC_CLASS_KEY` Configuration key for the class to use when encoding cells in the WAL

Constructor Summary

Constructors
Constructor and Description
`WALCellCodec()` All subclasses must implement a no argument constructor
`WALCellCodec(org.apache.hadoop.conf.Configuration conf, CompressionContext compression)` Default constructor - all subclasses must implement a constructor with this signature if they are to be dynamically loaded from the `Configuration`.

Method Summary

Methods
Modifier and Type	Method and Description
`static WALCellCodec`	`create(org.apache.hadoop.conf.Configuration conf, CompressionContext compression)` Create and setup a `WALCellCodec` from the CompressionContext.
`static WALCellCodec`	`create(org.apache.hadoop.conf.Configuration conf, String cellCodecClsName, CompressionContext compression)` Create and setup a `WALCellCodec` from the `cellCodecClsName` and CompressionContext, if `cellCodecClsName` is specified.
`WALCellCodec.ByteStringCompressor`	`getByteStringCompressor()`
`WALCellCodec.ByteStringUncompressor`	`getByteStringUncompressor()`
`Codec.Decoder`	`getDecoder(InputStream is)`
`Codec.Encoder`	`getEncoder(OutputStream os)`
`static Class<?>`	`getWALCellCodecClass(org.apache.hadoop.conf.Configuration conf)`
`private static byte[]`	`uncompressByteString(com.google.protobuf.ByteString bs, Dictionary dict)`

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

- Field Detail
  - WAL_CELL_CODEC_CLASS_KEY
```
public static final String WAL_CELL_CODEC_CLASS_KEY
```
    Configuration key for the class to use when encoding cells in the WAL
    
    See Also:
    Constant Field Values
  - compression
```
protected final CompressionContext compression
```
  - statelessUncompressor
```
protected final WALCellCodec.ByteStringUncompressor statelessUncompressor
```
- Constructor Detail
  - WALCellCodec
```
public WALCellCodec()
```
    All subclasses must implement a no argument constructor
  - WALCellCodec
```
public WALCellCodec(org.apache.hadoop.conf.Configuration conf,
            CompressionContext compression)
```
    Default constructor - all subclasses must implement a constructor with this signature if they are to be dynamically loaded from the Configuration.
    
    Parameters:
    conf - configuration to configure this
    compression - compression the codec should support, can be null to indicate no compression
- Method Detail
  - getWALCellCodecClass
```
public static Class<?> getWALCellCodecClass(org.apache.hadoop.conf.Configuration conf)
```
  - create
```
public static WALCellCodec create(org.apache.hadoop.conf.Configuration conf,
                  String cellCodecClsName,
                  CompressionContext compression)
                           throws UnsupportedOperationException
```
    Create and setup a WALCellCodec from the cellCodecClsName and CompressionContext, if cellCodecClsName is specified. Otherwise Cell Codec classname is read from Configuration. Fully prepares the codec for use.
    
    Parameters:
    conf - Configuration to read for the user-specified codec. If none is specified, uses a WALCellCodec.
    compression - compression the codec should use
    
    Returns:
    a WALCellCodec ready for use.
    
    Throws:
    
    UnsupportedOperationException - if the codec cannot be instantiated
  - create
```
public static WALCellCodec create(org.apache.hadoop.conf.Configuration conf,
                  CompressionContext compression)
                           throws UnsupportedOperationException
```
    Create and setup a WALCellCodec from the CompressionContext. Cell Codec classname is read from Configuration. Fully prepares the codec for use.
    
    Parameters:
    conf - Configuration to read for the user-specified codec. If none is specified, uses a WALCellCodec.
    compression - compression the codec should use
    
    Returns:
    a WALCellCodec ready for use.
    
    Throws:
    
    UnsupportedOperationException - if the codec cannot be instantiated
  - uncompressByteString
```
private static byte[] uncompressByteString(com.google.protobuf.ByteString bs,
                          Dictionary dict)
                                    throws IOException
```
    Throws:
    
    IOException
  - getDecoder
```
public Codec.Decoder getDecoder(InputStream is)
```
    Specified by:
    
    getDecoder in interface Codec
  - getEncoder
```
public Codec.Encoder getEncoder(OutputStream os)
```
    Specified by:
    
    getEncoder in interface Codec
  - getByteStringCompressor
```
public WALCellCodec.ByteStringCompressor getByteStringCompressor()
```
  - getByteStringUncompressor
```
public WALCellCodec.ByteStringUncompressor getByteStringUncompressor()
```

Class WALCellCodec

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.hadoop.hbase.codec.Codec

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

WAL_CELL_CODEC_CLASS_KEY

compression

statelessUncompressor

Constructor Detail

WALCellCodec

WALCellCodec

Method Detail

getWALCellCodecClass

create

create

uncompressByteString

getDecoder

getEncoder

getByteStringCompressor

getByteStringUncompressor