org.apache.hadoop.hbase.io
Class HbaseObjectWritable

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

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, WritableWithSize, org.apache.hadoop.io.Writable

public class HbaseObjectWritable
extends java.lang.Object
implements org.apache.hadoop.io.Writable, WritableWithSize, org.apache.hadoop.conf.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()
default constructor for writable

HbaseObjectWritable(java.lang.Class<?> declaredClass, java.lang.Object instance)

HbaseObjectWritable(java.lang.Object instance)

Method Summary

java.lang.Object	get()
org.apache.hadoop.conf.Configuration	getConf()
java.lang.Class<?>	getDeclaredClass()
long	getWritableSize() Provide a size hint to the caller.
static long	getWritableSize(java.lang.Object instance, java.lang.Class declaredClass, org.apache.hadoop.conf.Configuration conf)
void	readFields(java.io.DataInput in)
static java.lang.Object	readObject(java.io.DataInput in, org.apache.hadoop.conf.Configuration conf) Read a Writable, String, primitive type, or an array of the preceding.
static java.lang.Object	readObject(java.io.DataInput in, HbaseObjectWritable objectWritable, org.apache.hadoop.conf.Configuration conf) Read a Writable, String, primitive type, or an array of the preceding.
void	set(java.lang.Object instance) Reset the instance.
void	setConf(org.apache.hadoop.conf.Configuration conf)
java.lang.String	toString()
void	write(java.io.DataOutput out)
static void	writeObject(java.io.DataOutput out, java.lang.Object instance, java.lang.Class declaredClass, org.apache.hadoop.conf.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()

default constructor for writable

HbaseObjectWritable

public HbaseObjectWritable(java.lang.Object instance)

Parameters:

instance -

HbaseObjectWritable

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

Parameters:

declaredClass -

instance -

Method Detail

get

public java.lang.Object get()

Returns:

the instance, or null if none.

getDeclaredClass

public java.lang.Class<?> getDeclaredClass()

Returns:

the class this is meant to be.

set

public void set(java.lang.Object instance)

Reset the instance.

Parameters:

instance -

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()

readFields

public void readFields(java.io.DataInput in)
                throws java.io.IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Throws:

java.io.IOException

write

public void write(java.io.DataOutput out)
           throws java.io.IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Throws:

java.io.IOException

getWritableSize

public long getWritableSize()

Description copied from interface: WritableWithSize

Provide a size hint to the caller. write() should ideally not go beyond this if at all possible. You can return 0 if there is no size hint.

Specified by:

getWritableSize in interface WritableWithSize

Returns:

the size of the writable

getWritableSize

public static long getWritableSize(java.lang.Object instance,
                                   java.lang.Class declaredClass,
                                   org.apache.hadoop.conf.Configuration conf)

writeObject

public static void writeObject(java.io.DataOutput out,
                               java.lang.Object instance,
                               java.lang.Class declaredClass,
                               org.apache.hadoop.conf.Configuration conf)
                        throws java.io.IOException

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

Parameters:

out -

instance -

declaredClass -

conf -

Throws:

java.io.IOException

readObject

public static java.lang.Object readObject(java.io.DataInput in,
                                          org.apache.hadoop.conf.Configuration conf)
                                   throws java.io.IOException

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

Parameters:

in -

conf -

Returns:

the object

Throws:

java.io.IOException

readObject

public static java.lang.Object readObject(java.io.DataInput in,
                                          HbaseObjectWritable objectWritable,
                                          org.apache.hadoop.conf.Configuration conf)
                                   throws java.io.IOException

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

Parameters:

in -

objectWritable -

conf -

Returns:

the object

Throws:

java.io.IOException

setConf

public void setConf(org.apache.hadoop.conf.Configuration conf)

Specified by:

setConf in interface org.apache.hadoop.conf.Configurable

getConf

public org.apache.hadoop.conf.Configuration getConf()

Specified by:

getConf in interface org.apache.hadoop.conf.Configurable