org.apache.hadoop.hbase.io
Class HbaseObjectWritable

java.lang.Object
  org.apache.hadoop.hbase.io.HbaseObjectWritable

All Implemented Interfaces:

Configurable, Writable

public class HbaseObjectWritable
extends Object
implements Writable, Configurable

This is a customized version of the polymorphic hadoop ObjectWritable. It removes UTF8 (HADOOP-414). Using Text intead of UTF-8 saves ~2% CPU between reading and writing objects running a short sequentialWrite Performance Evaluation test just in ObjectWritable alone; more when we're doing randomRead-ing. Other optimizations include our passing codes for classes instead of the actual class names themselves. This makes it so this class needs amendment if non-Writable classes are introduced -- if passed a Writable for which we have no code, we just do the old-school passing of the class name, etc. -- but passing codes the savings are large particularly when cell data is small (If < a couple of kilobytes, the encoding/decoding of class name and reflection to instantiate class was costing in excess of the cell handling).

Field Summary

protected static org.apache.commons.logging.Log

LOG

Constructor Summary

HbaseObjectWritable()

HbaseObjectWritable(Class<?> declaredClass, Object instance)

HbaseObjectWritable(Object instance)

Method Summary

Object	get() Return the instance, or null if none.
Configuration	getConf() Return the configuration used by this object.
Class<?>	getDeclaredClass() Return the class this is meant to be.
void	readFields(DataInput in) Deserialize the fields of this object from in.
static Object	readObject(DataInput in, Configuration conf) Read a Writable, String, primitive type, or an array of the preceding.
static Object	readObject(DataInput in, HbaseObjectWritable objectWritable, Configuration conf) Read a Writable, String, primitive type, or an array of the preceding.
void	set(Object instance) Reset the instance.
void	setConf(Configuration conf) Set the configuration to be used by this object.
String	toString()
void	write(DataOutput out) Serialize the fields of this object to out.
static void	writeObject(DataOutput out, Object instance, Class declaredClass, Configuration conf) Write a Writable, String, primitive type, or an array of the preceding.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

protected static final org.apache.commons.logging.Log LOG

Constructor Detail

HbaseObjectWritable

public HbaseObjectWritable()

HbaseObjectWritable

public HbaseObjectWritable(Object instance)

HbaseObjectWritable

public HbaseObjectWritable(Class<?> declaredClass,
                           Object instance)

Method Detail

get

public Object get()

Return the instance, or null if none.

getDeclaredClass

public Class<?> getDeclaredClass()

Return the class this is meant to be.

set

public void set(Object instance)

Reset the instance.

toString

public String toString()

Overrides:

toString in class Object

readFields

public void readFields(DataInput in)
                throws IOException

Description copied from interface: Writable

Deserialize the fields of this object from in.

For efficiency, implementations should attempt to re-use storage in the existing object where possible.

Specified by:

readFields in interface Writable

Parameters:

in - DataInput to deseriablize this object from.

Throws:

IOException

write

public void write(DataOutput out)
           throws IOException

Description copied from interface: Writable

Serialize the fields of this object to out.

Specified by:

write in interface Writable

Parameters:

out - DataOuput to serialize this object into.

Throws:

IOException

writeObject

public static void writeObject(DataOutput out,
                               Object instance,
                               Class declaredClass,
                               Configuration conf)
                        throws IOException

Write a Writable, String, primitive type, or an array of the preceding.

Throws:

IOException

readObject

public static Object readObject(DataInput in,
                                Configuration conf)
                         throws IOException

Read a Writable, String, primitive type, or an array of the preceding.

Throws:

IOException

readObject

public static Object readObject(DataInput in,
                                HbaseObjectWritable objectWritable,
                                Configuration conf)
                         throws IOException

Read a Writable, String, primitive type, or an array of the preceding.

Throws:

IOException

setConf

public void setConf(Configuration conf)

Description copied from interface: Configurable

Set the configuration to be used by this object.

Specified by:

setConf in interface Configurable

getConf

public Configuration getConf()

Description copied from interface: Configurable

Return the configuration used by this object.

Specified by:

getConf in interface Configurable