org.apache.giraph.writable.kryo

Class GiraphClassResolver

java.lang.Object

com.esotericsoftware.kryo.util.DefaultClassResolver

org.apache.giraph.writable.kryo.GiraphClassResolver

All Implemented Interfaces:

com.esotericsoftware.kryo.ClassResolver

public class GiraphClassResolver
extends com.esotericsoftware.kryo.util.DefaultClassResolver

In order to avoid writing class names to the stream, this class resolver assigns unique integers to each class name and writes/reads those integers to/from the stream. Reads assume that there is already a class assigned to the given integer. This resolver only assigns unique integers for classes that are not explicitly registered since those classes are already assigned unique integers at the time of registration. This implementation uses zookeeper to provide consistent class name to ID mapping across all + nodes. If resolver encounters a class name that has not been assigned to a unique integer yet, it creates a class node in zookeeper under a designated path with persistent_sequential mode - allowing the file name of the class node to be suffixed with an auto incremented integer. After the class node is created, the resolver reads back all the nodes under the designated path and uses the unique suffix as the class id. If there are duplicate entries for the same class name due to some race condition, the lowest suffix is used.

Field Summary

Fields inherited from class com.esotericsoftware.kryo.util.DefaultClassResolver

classToNameId, classToRegistration, idToRegistration, kryo, NAME, nameIdToClass, nameToClass, nextNameId

Constructor Summary

Constructors

Constructor and Description
GiraphClassResolver()

Method Summary

Modifier and Type	Method and Description
static void	createClassName(String className) Creates a new node for the given class name.
static int	getClassId(String className) Gets ID for the given class name.
static String	getClassName(int id) Get class name for given ID.
protected Class<?>	getTypeByName(String className) Get type by class name.
static boolean	isInitialized() Return true of the zookeeper is initialized.
com.esotericsoftware.kryo.Registration	readClass(com.esotericsoftware.kryo.io.Input input)
protected com.esotericsoftware.kryo.Registration	readName(com.esotericsoftware.kryo.io.Input input) This method reads the class name for the first encountered non-explicitly registered class.
static void	refreshCache() Refreshes class-ID mapping from zookeeper.
com.esotericsoftware.kryo.Registration	register(com.esotericsoftware.kryo.Registration registration)
com.esotericsoftware.kryo.Registration	registerImplicit(Class type)
void	reset() Reset the internal state Reset clears two hash tables: 1 - Class name to ID: Every non-explicitly registered class takes the ID agreed by all kryo instances, and it doesn't change across serializations, so this reset is not required.
static void	setZookeeperInfo(ZooKeeperExt zookeeperExt, String kryoClassPath) Sets zookeeper informaton.
com.esotericsoftware.kryo.Registration	writeClass(com.esotericsoftware.kryo.io.Output output, Class type)
protected void	writeName(com.esotericsoftware.kryo.io.Output output, Class type, com.esotericsoftware.kryo.Registration registration) This method writes the class name for the first encountered non-explicitly registered class.

Methods inherited from class com.esotericsoftware.kryo.util.DefaultClassResolver

getRegistration, getRegistration, setKryo

Methods inherited from class java.lang.Object

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

Constructor Detail

GiraphClassResolver

public GiraphClassResolver()

Method Detail

setZookeeperInfo

public static void setZookeeperInfo(ZooKeeperExt zookeeperExt,
                                    String kryoClassPath)

Sets zookeeper informaton.

Parameters:

zookeeperExt - ZookeeperExt

kryoClassPath - Zookeeper directory path where class Name-ID mapping is stored.

isInitialized

public static boolean isInitialized()

Return true of the zookeeper is initialized.

Returns:

True if the zookeeper is initialized.

createClassName

public static void createClassName(String className)

Creates a new node for the given class name. Creation mode is persistent sequential, i.e. ZK will always create a new node . There could be multiple entries for the same class name but since the lowest index is used, this is not a problem.

Parameters:

className - Class name

refreshCache

public static void refreshCache()

Refreshes class-ID mapping from zookeeper. Not thread safe.

getClassId

public static int getClassId(String className)

Gets ID for the given class name.

Parameters:

className - Class name

Returns:

class id Class ID

getClassName

public static String getClassName(int id)

Get class name for given ID.

Parameters:

id - class ID

Returns:

class name

register

public com.esotericsoftware.kryo.Registration register(com.esotericsoftware.kryo.Registration registration)

Specified by:

register in interface com.esotericsoftware.kryo.ClassResolver

Overrides:

register in class com.esotericsoftware.kryo.util.DefaultClassResolver

registerImplicit

public com.esotericsoftware.kryo.Registration registerImplicit(Class type)

Specified by:

registerImplicit in interface com.esotericsoftware.kryo.ClassResolver

Overrides:

registerImplicit in class com.esotericsoftware.kryo.util.DefaultClassResolver

writeClass

public com.esotericsoftware.kryo.Registration writeClass(com.esotericsoftware.kryo.io.Output output,
                                                         Class type)

Specified by:

writeClass in interface com.esotericsoftware.kryo.ClassResolver

Overrides:

writeClass in class com.esotericsoftware.kryo.util.DefaultClassResolver

readClass

public com.esotericsoftware.kryo.Registration readClass(com.esotericsoftware.kryo.io.Input input)

Specified by:

readClass in interface com.esotericsoftware.kryo.ClassResolver

Overrides:

readClass in class com.esotericsoftware.kryo.util.DefaultClassResolver

reset

public void reset()

Reset the internal state Reset clears two hash tables: 1 - Class name to ID: Every non-explicitly registered class takes the ID agreed by all kryo instances, and it doesn't change across serializations, so this reset is not required. 2- Reference tracking: Not required because it is disabled. Therefore, this method should not be invoked.

Specified by:

reset in interface com.esotericsoftware.kryo.ClassResolver

Overrides:

reset in class com.esotericsoftware.kryo.util.DefaultClassResolver

writeName

protected void writeName(com.esotericsoftware.kryo.io.Output output,
                         Class type,
                         com.esotericsoftware.kryo.Registration registration)

This method writes the class name for the first encountered non-explicitly registered class. Since all non-explicitly registered classes take the ID agreed by all kryo instances, there is no need to write the class name, so this method should not be invoked.

Overrides:

writeName in class com.esotericsoftware.kryo.util.DefaultClassResolver

Parameters:

output - Output stream

type - CLass type

registration - Registration

readName

protected com.esotericsoftware.kryo.Registration readName(com.esotericsoftware.kryo.io.Input input)

This method reads the class name for the first encountered non-explicitly registered class. Since all non-explicitly registered classes take the ID agreed by all kryo instances, class name is never written, so this method should not be invoked.

Overrides:

readName in class com.esotericsoftware.kryo.util.DefaultClassResolver

Parameters:

input - Input stream

Returns:

Registration

getTypeByName

protected Class<?> getTypeByName(String className)

Get type by class name.

Overrides:

getTypeByName in class com.esotericsoftware.kryo.util.DefaultClassResolver

Parameters:

className - Class name

Returns:

class type