cs138.chord
Class ChordNodeImpl

java.lang.Object
  cs138.chord.ChordNodeImpl

All Implemented Interfaces:

ChordNode, RemoteChordNode, ManageableNode, java.rmi.Remote

public class ChordNodeImpl
extends java.lang.Object
implements RemoteChordNode

This class is our main implementation of a ChordNode

Author:

rm

Constructor Summary

ChordNodeImpl()
Creates a new Chord node with the given identifier.

Method Summary

RemoteChordNode	findSuccessor(java.math.BigInteger hash) Find the Chord node responsible for the given key.
java.io.Serializable	get(java.lang.String key) The publicly available "get" method.
ChordNode[]	getFingerTable()
java.lang.String	getIdentifier()
java.util.List<java.lang.String>	getKeys()
java.io.Serializable	getLocal(java.lang.String key) Get the data associated with the specified key.
java.lang.Class<? extends NodeMonitor>	getMonitorInterface() This returns the Node implementation specific monitor that will be used.
java.math.BigInteger	getNodeHash()
int	getNumKeys()
ChordNode	getPredecessor()
ChordNode	getSuccessor()
void	initialize(java.lang.String id, ManageableNode node, NodeMonitor monitor) Initializes a new node
boolean	isReady() Determines that the node in question has been set up and is ready to be used.
void	leave() Called when the node wants to leave the Chord ring.
ChordNode	locate(java.lang.String key) Find the Chord node responsible for the given key.
void	notify(RemoteChordNode node) The caller of this method believes that "node" should be this node's predecessor.
void	ping() This method is used in nodes to determine that they are still up.
boolean	put(java.lang.String key, java.io.Serializable data) The publicly available "put" method.
boolean	putLocal(java.lang.String key, java.io.Serializable data) Insert a key-value pair into the hash table.

Methods inherited from class java.lang.Object

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

Constructor Detail

ChordNodeImpl

public ChordNodeImpl()
              throws java.rmi.RemoteException

Creates a new Chord node with the given identifier. The node is not used until it's managed node is initialized.

Throws:

java.rmi.RemoteException

Method Detail

initialize

public void initialize(java.lang.String id,
                       ManageableNode node,
                       NodeMonitor monitor)
                throws java.rmi.RemoteException

Description copied from interface: ManageableNode

Initializes a new node

Specified by:

initialize in interface ManageableNode

Parameters:

id - The identifier of the node

node - A gateway node, may be null

monitor - The default monitor to attach

Throws:

java.rmi.RemoteException

findSuccessor

public RemoteChordNode findSuccessor(java.math.BigInteger hash)
                              throws java.rmi.RemoteException

Find the Chord node responsible for the given key. If the key resides between this node and its successor, return the successor. Otherwise, find the closest preceding node in your finger table and ask it to locate the successor of the key. Don't forget to protect your access to the finger table.

Specified by:

findSuccessor in interface RemoteChordNode

Parameters:

hash - The hash of the key you are looking for

Returns:

The node that is responsible for the hashed key.

Throws:

java.rmi.RemoteException

notify

public void notify(RemoteChordNode node)
            throws java.rmi.RemoteException

The caller of this method believes that "node" should be this node's predecessor. We should verify this claim, and if it is true we should update our predecessor. Remember the new predecessor might be responsible for some of the keys we are currently holding. Make sure that the predecessor cannot be changed by another thread while we are verifying or transferring keys.

Specified by:

notify in interface RemoteChordNode

Parameters:

node - The node that believes it is the new predecessor

Throws:

java.rmi.RemoteException

leave

public void leave()
           throws java.rmi.RemoteException

Called when the node wants to leave the Chord ring. WARNING: This is a graceless leave.

Specified by:

leave in interface ChordNode

Throws:

java.rmi.RemoteException

get

public java.io.Serializable get(java.lang.String key)
                         throws java.rmi.RemoteException

The publicly available "get" method. Locates the appropriate node and gets the value associated with the key from that node.

Specified by:

get in interface ChordNode

Throws:

java.rmi.RemoteException

getLocal

public java.io.Serializable getLocal(java.lang.String key)
                              throws java.rmi.RemoteException

Get the data associated with the specified key. Warning: the predecessor may be the actual owner of the key. If your predecessor recently joined the ring, other nodes may not be aware of it yet. You should forward the get request to the predecessor if it is the rightful owner. Protect your access to the predecessor with a lock on _table.

Specified by:

getLocal in interface RemoteChordNode

Parameters:

key - The key to look up.

Returns:

The value associated with the key.

Throws:

java.rmi.RemoteException

put

public boolean put(java.lang.String key,
                   java.io.Serializable data)
            throws java.rmi.RemoteException

The publicly available "put" method. Locates the appropriate node and inserts the key-value pair at that node. TODO Fill me out

Specified by:

put in interface ChordNode

Throws:

java.rmi.RemoteException

putLocal

public boolean putLocal(java.lang.String key,
                        java.io.Serializable data)
                 throws java.rmi.RemoteException

Insert a key-value pair into the hash table. Objects in this DHT are immutable, so don't overwrite the value for a key if it already exists in the hash table. Warning: the predecessor may be the actual owner of the key. If your predecessor recently joined the ring, other nodes may not be aware of it yet. You should forward the put request to the predecessor if it is the rightful owner. Protect your access to the predecessor with a lock on _table.

Specified by:

putLocal in interface RemoteChordNode

Parameters:

key - The key.

data - The value associated with the key.

Returns:

True if the insertion is successful.

Throws:

java.rmi.RemoteException

locate

public ChordNode locate(java.lang.String key)
                 throws java.rmi.RemoteException

Find the Chord node responsible for the given key. You should just use findSuccessor().

Specified by:

locate in interface ChordNode

Parameters:

key - The key to locate.

Returns:

The Chord node responsible for the key.

Throws:

java.rmi.RemoteException

getFingerTable

public ChordNode[] getFingerTable()
                           throws java.rmi.RemoteException

Specified by:

getFingerTable in interface ChordNode

Throws:

java.rmi.RemoteException

getIdentifier

public java.lang.String getIdentifier()
                               throws java.rmi.RemoteException

Specified by:

getIdentifier in interface ChordNode

Throws:

java.rmi.RemoteException

getKeys

public java.util.List<java.lang.String> getKeys()
                                         throws java.rmi.RemoteException

Specified by:

getKeys in interface ChordNode

Throws:

java.rmi.RemoteException

getNodeHash

public java.math.BigInteger getNodeHash()
                                 throws java.rmi.RemoteException

Specified by:

getNodeHash in interface ChordNode

Throws:

java.rmi.RemoteException

getNumKeys

public int getNumKeys()
               throws java.rmi.RemoteException

Specified by:

getNumKeys in interface ChordNode

Throws:

java.rmi.RemoteException

getPredecessor

public ChordNode getPredecessor()
                         throws java.rmi.RemoteException

Specified by:

getPredecessor in interface ChordNode

Throws:

java.rmi.RemoteException

getSuccessor

public ChordNode getSuccessor()
                       throws java.rmi.RemoteException

Specified by:

getSuccessor in interface ChordNode

Throws:

java.rmi.RemoteException

isReady

public boolean isReady()
                throws java.rmi.RemoteException

Description copied from interface: ChordNode

Determines that the node in question has been set up and is ready to be used.

Specified by:

isReady in interface ChordNode

Returns:

True if ready, false otherwise

Throws:

java.rmi.RemoteException

ping

public void ping()
          throws java.rmi.RemoteException

Description copied from interface: ManageableNode

This method is used in nodes to determine that they are still up.

Specified by:

ping in interface ManageableNode

Throws:

java.rmi.RemoteException

getMonitorInterface

public java.lang.Class<? extends NodeMonitor> getMonitorInterface()
                                                           throws java.rmi.RemoteException

Description copied from interface: ManageableNode

This returns the Node implementation specific monitor that will be used.

Specified by:

getMonitorInterface in interface ManageableNode

Returns:

The class object corresponding to the Monitor Interface being used.

Throws:

java.rmi.RemoteException