Class MyChord

java.lang.Object
  |
  +--MyChord

public class MyChord

extends java.lang.Object

Basic Chord implementation. This is a simple implementation that should permit development to progress. The current implementation is not particularly robust to failure, is quite inefficient, and is not scalable. It utilizes a centralised server that will make the timing relationships easier to work with. If there is demand I will attempt to supply a more scalable version with an identical interface. The class uses two different handlers depending on whether it is the master node that retains the list of all nodes or it is a normal node that queries the master node to get information.

Inner Class Summary

protected class	MyChord.MasterHandler Inner class to handle one interaction for the master node.
protected class	MyChord.StandardHandler Inner class to handle one interaction for the standard node.

Field Summary

protected MyChange	change
protected boolean	closing
protected int	debug
protected ChordLocation	here
protected ChordLocation	master
protected java.net.ServerSocket	servSock

Method Summary

protected void	add(ChordLocation node) Add adds a node to the list.
protected void	delete(ChordLocation node) Deletes a node from the list when it leaves the ring.
void	leave() We call this when we want to leave the chord ring.
protected void	log(java.lang.String s) Shorthand for a print statement.
protected int	lookKey(byte[] key) LookKey looks up a key in the list of locations.
ChordLocation	lookUp(byte[] key) This looks up a key in the Chord ring.
protected void	printNodes() Used for debugging, this prints an ordered list of nodes.
void	runServer() This is the method that kicks off a server.

Methods inherited from class java.lang.Object

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

Field Detail

change

protected MyChange change

here

protected ChordLocation here

master

protected ChordLocation master

servSock

protected java.net.ServerSocket servSock

debug

protected int debug

closing

protected boolean closing

Method Detail

printNodes

protected void printNodes()

Used for debugging, this prints an ordered list of nodes.

lookKey

protected int lookKey(byte[] key)

LookKey looks up a key in the list of locations.

add

protected void add(ChordLocation node)

Add adds a node to the list. It is synchronised to ensure simultaneous adds do not interfere.

delete

protected void delete(ChordLocation node)

Deletes a node from the list when it leaves the ring. Again, this is synchronized to avoid interference between different leaves and joins.

lookUp

public ChordLocation lookUp(byte[] key)

This looks up a key in the Chord ring. It is implemented by sending messages to the server to access the list.

leave

public void leave()

We call this when we want to leave the chord ring. This has the side effect of calling change.left and shutting off the server.

runServer

public void runServer()

This is the method that kicks off a server. When you call it, it loops until closing is set to true, indicating the server is closing down.

log

protected void log(java.lang.String s)

Shorthand for a print statement.