org.iperg.part.core
Class IpIdentifier

java.lang.Object
  org.iperg.part.core.IpIdentifier

All Implemented Interfaces:

IpSerializable

public class IpIdentifier
extends java.lang.Object
implements IpSerializable

The IpIdentifier class represents identifiers that may be unique in time and space. That is, an instance of the IpIdentifier class that is created at a specific time by an IPerG process can be made unique in relation to all other IpIdentifier instances created by other IPerG processes at any time.

Depending on the way in which IpIdentifier instances are created, they may or may not be unique. For instance, using the empty constructor will create an identifier that is not unique in time and space:

 IpIdentifier id = new IpIdentifier(); 

An identifier can be made unique by callings its makeUnique method.

 id.makeUnique();

If an identifier is created by passing a byte stream to the constructor, the new identifier uniqueness wull dependend on the data encoded in the stream.

 IpIdentifier id = new IpIdentifier(stream); 

Version:

1.0.0 Initial version

Author:

Olov Stahl - olovs@sics.se

Constructor Summary

IpIdentifier()
Create a new zero identifier which is NOT be unique.

IpIdentifier(IpIdentifier srcId)
Create a new identifier which is a copy of another identifier.

IpIdentifier(IpInputStream stream)
Create a new identifier by reading data from an input stream.

Method Summary

boolean	equals(java.lang.Object obj) Check if the identifier equals another object (identifier)
static IpIdentifier	fromString(java.lang.String s) Return a new IpIdentifier initialised by a string representation.
int	hashCode() Return a hash value for the identifier.
boolean	isZero() Check if the identifier is a "zero" identifier
void	makeReadOnly() By making the object read only, its state can not be modified, e.g., by calling the read method.
void	makeUnique() Make sure that the identifier is unique in time and space
static IpIdentifier	newUniqueId() Create and return a new unique identifier instance.
void	read(IpInputStream stream) Read the state of the process object from an input stream.
void	setIncarnation(short incarnation)
java.lang.String	toString() Return a string representation of a identifier
void	write(IpOutputStream stream) Write the state of the process object into an putput stream .

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

IpIdentifier

public IpIdentifier()

Create a new zero identifier which is NOT be unique.

IpIdentifier

public IpIdentifier(IpIdentifier srcId)

Create a new identifier which is a copy of another identifier. The identifier will be unique if the source identifier is unique.

Parameters:

srcId - The identifier to copy

IpIdentifier

public IpIdentifier(IpInputStream stream)
             throws java.io.IOException

Create a new identifier by reading data from an input stream. The identifier will be unique if the identifier whose state is encoded on the stream is unique.

Throws:

java.io.IOException

Method Detail

makeUnique

public void makeUnique()

Make sure that the identifier is unique in time and space

makeReadOnly

public void makeReadOnly()

By making the object read only, its state can not be modified, e.g., by calling the read method.

isZero

public boolean isZero()

Check if the identifier is a "zero" identifier

Returns:

true if identifier is a zero identifier, false otherwise

equals

public boolean equals(java.lang.Object obj)

Check if the identifier equals another object (identifier)

Overrides:

equals in class java.lang.Object

Parameters:

obj - The other object (identifier)

Returns:

true if identifiers are equal, false otherwise

write

public void write(IpOutputStream stream)

Write the state of the process object into an putput stream .

Specified by:

write in interface IpSerializable

Parameters:

stream - The output stream into which the process object's state should be written

Throws:

java.io.IOException - if an io exception occured while writing the identifier to the stream

read

public void read(IpInputStream stream)

Read the state of the process object from an input stream.

Specified by:

read in interface IpSerializable

Parameters:

stream - The input stream object from which the process object's state should be read

Throws:

java.io.IOException - if marshalling failed

toString

public java.lang.String toString()

Return a string representation of a identifier

Overrides:

toString in class java.lang.Object

fromString

public static IpIdentifier fromString(java.lang.String s)

Return a new IpIdentifier initialised by a string representation. The string must have been returned from the toString method:

 IpIdentifier id1 = new IpIdentifier();
 IpIdentifier id2 = IpIdentifier.fromString(id1.toString());

Returns:

A new identifier or null if string could not be parsed

newUniqueId

public static IpIdentifier newUniqueId()

Create and return a new unique identifier instance.

Returns:

THe new identifier

hashCode

public int hashCode()

Return a hash value for the identifier. We want to make sure that two identifier instances that are "equal" (i.e., their time, host and pid variable values are equal) return the same hash value.

Overrides:

hashCode in class java.lang.Object

Returns:

A hash value for the identifier

setIncarnation

public void setIncarnation(short incarnation)